Solar Upgrade AGAIN

[EEVblog]

We want to upgrade our solar power system AGAIN.
Currently have:
A. 5kw Enphase system with 14x295W microinverters with 380W LG panels on north-north-west roof
B. Old 3kW system with 12x250W LG panels and 3kQ Sunnyboy inverter on a now non-ideal east-east-south roof

Mrs EEVblog has now approved more panels on the front of the house (north-north-east roof) where she previously didn't want because of looks. (You can't see either of our systems from the street)
We are going to extend our house upwards, on the roof where both existing systems are now present. So we'll have no solar at all during the building period.
Dosn't make much sense to reinstall the old 3kW system on the new extended roof once finished, so makes sense to upgrade it and move to the front roof of the house.

The old 3kW system isn't of much use now in winter time, so thinking about selling the panels and inverter and reusing the racking for a new system on the front of the house.

So options seem to be:
1) Upgrade and move the old 3kw system to the front roof. New 400W-ish panels and possibly a free 5kW+ Fronius inverter they have offered me in the past. But I'd still have two separate systems from a monitoring point of view.

2) New system on the front roof that uses Enphase micro-inverters to extend the existing Enphase system. Most expensive solution, but would now only have one Enphase system. Lower voltage is safer, and potentially better shading performance (see photo from this morning when the other systems were producing almost nothing, shading is from a tree across the road due the low morning sun angle). Peak power output is lower because of the derated microinverters.

Could also just keep the old 3kW system just because we have it and it's paid for itself.
Long term plan is a 2nd EV (not charging at the same time, so no need for more peak power there), a pool with heat pump, and switching from gas to electric hot water. Hence the need for a bigger system.

Thoughts and comments please.
I like the enphase system, but it's expensive, and I kinda don't like the limited peak power output. On the other hand, I don't like having two different systems.

[Yanis]

We did an upgrade and the old racking was in place and perfectly fine. When they came to do the quote the guy (happened to be the owner) said leave the rails - they will be re-used. When the installers came they removed the old rails and used all new. It did not change the quote so I am thinking that the quote included everything including the rails. Not sure if you can get an installer to re-use old stuff and remove it form the quote.

We shopped around to get the best value for money as well. Some quotes were up to double what we paid.

[EEVblog]

We did an upgrade and the old racking was in place and perfectly fine. When they came to do the quote the guy (happened to be the owner) said leave the rails - they will be re-used. When the installers came they removed the old rails and used all new. It did not change the quote so I am thinking that the quote included everything including the rails. Not sure if you can get an installer to re-use old stuff and remove it form the quote.

We already reused the 3kW racking when it was moved during the last upgrade. Also, the DC isolators are new.
It's only racking for 12 panels though, we can almost certanly fit more on the front roof. Haven't measured it all yet though.

[floobydust]

I don't understand the lingo down under. You're adding a floor? is that what "extend our house upwards" means? Same roof slope?
The one tree branch tree looks dead, start the buzzsaw.

[dmcdonald]

I'm wondering if more/upgraded panels/inverters really ought to be the next step

I know you've ruled out batteries before, but it's a constantly changing/improving environment. I have issues with lithium based batteries for home use - the fire risk concerns me (incidentally, that's an argument in favour of micro inverters as you have previously identified), but there are different chemistries becoming available - Redflow in Qld have zinc-bromide flow battery systems already available, Gelion in Sydney will soon have zinc-bromide gel cells. There are vanadium chemistry batteries too

Even if not a solution for you, there's probably a few talking points (& people to interview) for future vlogs

[EEVblog]

I don't understand the lingo down under. You're adding a floor? is that what "extend our house upwards" means? Same roof slope?

Yes and Yes. So the existing 14 panels 5kW system will go back o nthe new higher up roof, improving the shading from the big house up the slope next door.

[EEVblog]

I'm wondering if more/upgraded panels/inverters really ought to be the next step

I just installed a new 14 panel Enphase system a year ago. No point upgrading that.
Yes the old 3kW 250W panel system could do with an upgrade. Although it's "free" except for reinstall cost so an argument could be made that we should just keep it.
The current system barely has the power output to charge the EV at the full 7kW in summer time, lets alone the pool heater and hot water system we plan on getting.

I know you've ruled out batteries before, but it's a constantly changing/improving environment. I have issues with lithium based batteries for home use - the fire risk concerns me (incidentally, that's an argument in favour of micro inverters as you have previously identified), but there are different chemistries becoming available - Redflow in Qld have zinc-bromide flow battery systems already available, Gelion in Sydney will soon have zinc-bromide gel cells. There are vanadium chemistry batteries too

Batteries will be reevaluated after the upgrade and we have performance data.
A company is sending me a 3.2kWh portable pack shortly, so I might use to power the fridges as a standalone system.

[bdunham7]

Thoughts and comments please.
I like the enphase system, but it's expensive, and I kinda don't like the limited peak power output. On the other hand, I don't like having two different systems.

How much 'clipping' are you seeing with your Enphase system?  And how are you paid/do you pay for power?

I like per-panel MPPT and monitoring, but I'm not sure how much more money I'd fork out to have them.  How expensive are SolarEdge systems in Australia?  You could do endless videos comparing them.  But to be sensible, it all boils down to a mostly economic decision. 

[EEVblog]

Oh, the other problem with the Enphase microinveretsr is the standby power, it's massive!
They only claim a few watts, but that's real power, apparent power sucks. 280VA for my 14 microinveretrs.
You don't pay for that of course, UNLESS you have a battery system and then the current doesn't come for "free" any more.

[Someone]

And how are you paid/do you pay for power?

Current electricity rates in Australia are roughly: 20-30c buy, 6-10c sell. Hard to make a profit on any "fancy" add-ons that arent paid for with a susbsidy/offset/externality. Solar barely profits for on grid consumers in Australia unless they sell their renewable energy credit (at which point you can argue the owner isnt consuming green energy anymore, unless they buy it back).

[uer166]

UNLESS you have a battery system and then the current doesn't come for "free" any more.

Is that true 1:1 or do you mean it as a generalization? It is my understanding that you don't have inherent kWh loss of a pack due to the reactive current, but I2R losses just like in normal AC distribution networks. This is assuming you have a system where the pack has a separate inverter that's grid tied of course. Like, your 280VA won't cause a 280Wh loss on the pack, but would me substantially lower (maybe in order of 10% of the VARs?), and depends on the round trip efficiency of the inverter/pack combo and wiring I2R losses etc..

Edit: I think I made a mistake, the issue must appear only if you're islanded, and the same stuff about it being less than 1:1 kWh:VAR applies.

[bdunham7]

Oh, the other problem with the Enphase microinveretsr is the standby power, it's massive!
They only claim a few watts, but that's real power, apparent power sucks. 280VA for my 14 microinveretrs.
You don't pay for that of course, UNLESS you have a battery system and then the current doesn't come for "free" any more.

That was actually one of the first things I noticed with my system after installation, but eventually I realized that not only don't you pay for it, but since it is essentially capacitance directly across the line it actually serves as a power factor correction since the load on the utility tends strongly toward lagging current.  A battery system would only have an issue (maybe) if it were off-grid and then only overnight with very small loads with no inductive motors.

[bdunham7]

Current electricity rates in Australia are roughly: 20-30c buy, 6-10c sell.

Is that with net metering or are you strongly incentivized to use what you produce in real time?

[EEVblog]

[Kleinstein]

The reactive power is not a real problem. Even if the battery system (with an extra inverter) would have to provide the reactive power, it does not need 280 W to produce 280 VA of reactive power. It would only have to provide the current and thus maybe some 5% of the reative power actually drawn from the battery. That is provided the capacity is sufficient - there could be a limit on how much reactive power the inverter can handle with no load.

The shading may be an argument for the microinverters on the front roof. For a string inverter it really depends on how good they can handle partial shading and also on how the cells are places in the modules. The old case with antenna shade was close to the wost case for the shape of the shaddow. Some shading when the sum is low is not that bad. That would be times with relatively low power anyway.

If the useful new area is large enough, there may be the option to have a 3rd completely separate system and leave the rest as is.

[Someone]

Current electricity rates in Australia are roughly: 20-30c buy, 6-10c sell.

Is that with net metering or are you strongly incentivized to use what you produce in real time?

"Net Metering" is not a well defined term:
https://en.wikipedia.org/wiki/Net_metering
That is not what Australia uses. The majority of solar installs in Australia are billed for incoming and outgoing power at different rates, but its metered through a single connection (point) so you are incentivized to self consume production rather than export at the large differential price. Then you are also usually capped on export rate (possibly even curtailed depending on grid conditions) and might have time of day rates

Some legacy installs were fully grossed meters, all production was sold at a fixed rate to the gird, and all consumption was purchased back from the grid (no self consumption):
https://www.solaranalytics.com.au/community-news/the-difference-between-net-and-gross-metering-for-nsw-solar-owners

The industry needs some unified worldwide terms.

[dreamcat4]

i dont necessarily think that this is applicable to your situation, but i always liked the idea of putting up pergolas in the garden, as a sort of diy project. and then mounting panels onto the top of those pergolas

aside from easier maintenance etc. i guess the other main upside is extra shading during summer months. however the downside is... the same thing: extra shading during winter months

but i suppose it depends if you really care much for the garden during winter time

i also think maybe pergolas, with the easier access would also permit re orienting the panels better for the winter season. to make sure they catch more light, and better gaps between for racking / not shading each other etc were you to want to be doing that. of course we know racking and angling is not space effecient vs just buying more flat panels. but maybe you dont actually want fully shaded garden either!

anyhow perolas in the garden as a diy project might not apply to you... it just seemed like one approach to try to keep the costs down. to be able to then afford more enphase inverters. just so long as you could also source some bargain dirt cheap ex-commercial panels to go with them

[bdunham7]

"Net Metering" is not a well defined term:
https://en.wikipedia.org/wiki/Net_metering
That is not what Australia uses. The majority of solar installs in Australia are billed for incoming and outgoing power at different rates, but its metered through a single connection (point) so you are incentivized to self consume production rather than export at the large differential price. Then you are also usually capped on export rate (possibly even curtailed depending on grid conditions) and might have time of day rates

I don't think there's a problem with the term 'net metering', but what you have there is clearly not it.  Now there are some shades and variations to net metering, such as where you have differing rates at different times of day as I do, but the buy/sell still cancel each other out until there is a 'net' bill at the end of the net metering period.

[grythumn]

I know you've ruled out batteries before, but it's a constantly changing/improving environment. I have issues with lithium based batteries for home use - the fire risk concerns me (incidentally, that's an argument in favour of micro inverters as you have previously identified), but there are different chemistries becoming available - Redflow in Qld have zinc-bromide flow battery systems already available, Gelion in Sydney will soon have zinc-bromide gel cells. There are vanadium chemistry batteries too

The LiFEPO4 server rack batteries are quite popular right now, at least in the enthusiasts forums. Safer chemistry, easy install, long cycle life. More expensive than a raw cell bank, of course, but you don't need to fab your own enclosure.

[bdunham7]

The reactive power is not a real problem.

No, as he said, it is an imaginary problem! 

Going by the figures presented, each microinverter is essentially a 1µF capacitor (~3K reactive impedance at 50Hz) in parallel with a 20K or so resistor.  It would be interesting to see how various inverters react to such a load in standalone (backup or off-grid) mode.  One thing I don't understand is the emphasis on the 'terrible' PF.  You could put a 0.7H inductor across the line to balance things out, but I'm not sure that would result an any reduction in the input power of the battery inverter driving the system, especially if it were an iron-core inductor.   

[ejeffrey]

I'd guess a decent inverter would be more efficient than an iron core 50 Hz inductor, assuming you need it running at night anyway for whatever 24 hour loads you have (i.e., don't count the battery inverter's standby power draw against the micro-inverters).

Dave's video conclusion is wrong/misleading: a battery inverter system would certainly not need to consumer 240 W of battery power to supply that load.  It will take some power, but at a rough guess it will be on the order of the inverter inefficiency * load.  For a 95% efficient inverter it would only be ~12W.  Maybe twice that because you probably loose the conversion losses both directions: forward and reflected power.  It's not nothing but it's equivalent to a few minutes of daytime power production.  If you have any significant inductive load like a ventilation fan that is cooling your house overnight with outside air this will be lost in the noise.

Power factor is an issue when you have to distribute over a long distances picking up big distribution and transformer losses.  Going from your roof to your garage isn't a big deal.

If Dave gets a battery system this will be easy to verify: put a current clamp around the DC battery lead, then measure the draw in the middle of the night.  Use the manual AC disconnect on the solar feed and see how much the battery draw changes with and without the inverters.  I'd certainly be interested to see my handwaving guess verified.

[ejeffrey]

Reactive power is also much more significant when it accompanies peak real power.  Your entire production / distribution system needs to be sized for peak apparent power and sees the highest losses when operating at peak power.  Idle nighttime reactive power isn't a big deal. 

[David Hess]

Mrs EEVblog has now approved more panels on the front of the house (north-north-east roof) where she previously didn't want because of looks. (You can't see either of our systems from the street)

Learn something from the movie Brainstorm, "But honey, you can plant flowers all around it!"

[Someone]

"Net Metering" is not a well defined term:
https://en.wikipedia.org/wiki/Net_metering
That is not what Australia uses. The majority of solar installs in Australia are billed for incoming and outgoing power at different rates, but its metered through a single connection (point) so you are incentivized to self consume production rather than export at the large differential price. Then you are also usually capped on export rate (possibly even curtailed depending on grid conditions) and might have time of day rates

I don't think there's a problem with the term 'net metering', but what you have there is clearly not it.  Now there are some shades and variations to net metering, such as where you have differing rates at different times of day as I do, but the buy/sell still cancel each other out until there is a 'net' bill at the end of the net metering period.

I agree that Australia does not have "net metering" as the US define it, but Australia reuses the term and that Wikipedia article tries to shoehorn all the different ways the term is used into a single thing. So trying to use the term "net metering" in an international forum/context immediately fails to convey any real meaning unless you want to constantly refer to the specific jurisdiction/rules/explanation.

... p.s. "net metering" that is 1:1 time shifting is broken, it doesn't price storage. For all the free market bluster of the US they sure like to add bizzare bureaucratic distortions to a free market (electricity, corn, steel, etc).

[bdunham7]

... p.s. "net metering" that is 1:1 time shifting is broken, it doesn't price storage. For all the free market bluster of the US they sure like to add bizzare bureaucratic distortions to a free market (electricity, corn, steel, etc).

Time shifting doesn't require storage, it requires the utility to increase or curtail other sources as needed to accommodate a 'priority' producer like solar.  Storage came later.  Utilities are regulated monopolies here, so there's no presumption that free market principles would apply...although they tried them once and got very badly burned (Enron).  The net metering policy for solar was an explicit cost imposed on the utility as a way of encouraging solar installations and meeting the mandate that a certain amount of power be produced by renewables like wind and solar.  I'm sure that my electric utility has lost money on my account over the past decade (they've even had to write me some small checks) and that was expected and intentional.

Edit:  You are right about there being some wiggle room in the definition of 'net', as even the instantaneous net metering you appear to have is far better than schemes that require you to sell all of your production at a low rate and then buy back all of what you need at a higher rate.

[Someone]

... p.s. "net metering" that is 1:1 time shifting is broken, it doesn't price storage. For all the free market bluster of the US they sure like to add bizzare bureaucratic distortions to a free market (electricity, corn, steel, etc).

Time shifting doesn't require storage, it requires the utility to increase or curtail other sources as needed to accommodate a 'priority' producer like solar.  Storage came later.

Depends how you define storage Fossil plants inherently have storage as does hydro, often called "dispatchable" generation. If they arent running and are sitting idle there is still a cost for storing that energy (particularity in lost operating profit!). 1:1 time shifting is a very big distortion on the market that would only make sense if all the generators were roughly equivalent in costs/characteristics, a fossil plant costed on operating12-18 hours per day delivers more expensive power per unit when operated for shorter hours. The approximation works ok when solar is a small % of the total generation capacity but those days are long gone (in the US and Australia). So the US will have to move away from 1:1 time shifting or accept that its a huge enforced subsidy for solar operators.

Just as a fixed rate consumer feed in/selling price shows its limitations/bluntness when solar is pushing past 30-50% of the generation during the day, with no accounting for the difference in market pricing on sunny or very cloudy days. Such schemes wont last as renewable sources increase in share of overall generation.

[bdunham7]

Storage = the electricity going out was put in storage by electricity going in, such as pumped hydro, battery, etc.  Dispatchable is a relative term, ranging from nuclear (not very dispatchable) to aero-based gas turbine (very).  Wind and solar can be curtailed easily enough to make them dispatchable, but that has typically been done less because of the cost recovery and greenwashing issues.

Just as a fixed rate consumer feed in/selling price shows its limitations/bluntness when solar is pushing past 30-50% of the generation during the day, with no accounting for the difference in market pricing on sunny or very cloudy days. Such schemes wont last as renewable sources increase in share of overall generation.

That has already happened here.  https://www.caiso.com/documents/flexibleresourceshelprenewables_fastfacts.pdf   California has passed the point where the grid can no longer simply absorb the maximum available production of solar power.  New installations don't get the same terms as older ones did because without storage (as defined above) the grid is pretty saturated with solar.  Also, electricity rates are now pretty high at peak times so the big thing now is battery systems that can almost entirely take you off grid, or completely if the situation warrants it.

[Someone]

Storage = the electricity going out was put in storage by electricity going in, such as pumped hydro, battery, etc.  Dispatchable is a relative term, ranging from nuclear (not very dispatchable) to aero-based gas turbine (very).  Wind and solar can be curtailed easily enough to make them dispatchable, but that has typically been done less because of the cost recovery and greenwashing issues.

You said time shifting doesnt require storage. Which is plainly incorrect unless the grid is so wildly over provisioned that energy is always in excess. The economics of 1:1 time shifting are a huge subsidy to those people using it, they get a utility (storage) for no cost.

[bdunham7]

You said time shifting doesnt require storage. Which is plainly incorrect unless the grid is so wildly over provisioned that energy is always in excess. The economics of 1:1 time shifting are a huge subsidy to those people using it, they get a utility (storage) for no cost.

I agree that 1:1 time shifting is apparent storage to the user, but it can be and is (or was) accomplished without using any storage (meaning electricity to storage to electricity).  If you call the fuel tank of a generator 'storage', well....  And, in fact, the grid here is overprovisioned in that manner, but even that isn't a huge issue if they can predict their needs accurately enough.  As far as it being a subsidy to the user, yes it was and quite deliberately, as I stated, for the express purpose of subsidizing solar power.  However, before things got saturated with solar, my system was actually helping the grid because it provided a bit of power right when the utilities were struggling the most to provide it and my neighbors were buying that electricity as I produced it and probably paying even more for it than I was getting.  Now they have plenty.

To make matters even a bit more interesting, since I would typically generate during the day when rates were high and then use at night when they were low, I was getting better than 1:1 time shifting, almost 1:3.  I could generate a surplus (exported) kWh in the day and use 3kWh at night and my net bill would be zero.  That party is mostly over, they now have the weekdays as off-peak until 4PM.

[ejeffrey]

  However, before things got saturated with solar, my system was actually helping the grid because it provided a bit of power right when the utilities were struggling the most to provide it and my neighbors were buying that electricity as I produced it and probably paying even more for it than I was getting.  Now they have plenty.

Another factor especially in California is that the distribution infrastructure is also oversubscribed.  Even 12-2pm when there is an overall energy surplus, in many places it's actually still helpful for you to produce electricity on your rooftop to supply your neighbor's AC to reduce the demand on regional distribution lines trying to keep up with everyone's AC.

[bdunham7]

Another factor especially in California is that the distribution infrastructure is also oversubscribed.  Even 12-2pm when there is an overall energy surplus, in many places it's actually still helpful for you to produce electricity on your rooftop to supply your neighbor's AC to reduce the demand on regional distribution lines trying to keep up with everyone's AC.

Yes, but they won't pay me for that, just the super-off-peak minimum rate.  I end up selling back power anyway unless I'm charging my EV, but now they are getting the better deal.  On the bright side it is a lot cheaper now to run the AC during the day until 4PM.

[EEVblog]

UNLESS you have a battery system and then the current doesn't come for "free" any more.

Is that true 1:1 or do you mean it as a generalization? It is my understanding that you don't have inherent kWh loss of a pack due to the reactive current, but I2R losses just like in normal AC distribution networks. This is assuming you have a system where the pack has a separate inverter that's grid tied of course. Like, your 280VA won't cause a 280Wh loss on the pack, but would me substantially lower (maybe in order of 10% of the VARs?), and depends on the round trip efficiency of the inverter/pack combo and wiring I2R losses etc..

Edit: I think I made a mistake, the issue must appear only if you're islanded, and the same stuff about it being less than 1:1 kWh:VAR applies.

Yes, after thinking about it I think this the case too. Enphase have also confirmed this.

[EEVblog]

Oh, the other problem with the Enphase microinveretsr is the standby power, it's massive!
They only claim a few watts, but that's real power, apparent power sucks. 280VA for my 14 microinveretrs.
You don't pay for that of course, UNLESS you have a battery system and then the current doesn't come for "free" any more.

That was actually one of the first things I noticed with my system after installation, but eventually I realized that not only don't you pay for it, but since it is essentially capacitance directly across the line it actually serves as a power factor correction since the load on the utility tends strongly toward lagging current.  A battery system would only have an issue (maybe) if it were off-grid and then only overnight with very small loads with no inductive motors.

Yep, 3 x 330nF caps per micro inverter.

[EEVblog]

Reactive power is also much more significant when it accompanies peak real power.  Your entire production / distribution system needs to be sized for peak apparent power and sees the highest losses when operating at peak power.  Idle nighttime reactive power isn't a big deal.

Yes, not a problem in terms of cable capacity because the solar will be on it's own radial, not carry any load current when the inverters are off at night.

[EEVblog]

Dave's video conclusion is wrong/misleading: a battery inverter system would certainly not need to consumer 240 W of battery power to supply that load.  It will take some power, but at a rough guess it will be on the order of the inverter inefficiency * load.  For a 95% efficient inverter it would only be ~12W.  Maybe twice that because you probably loose the conversion losses both directions: forward and reflected power.  It's not nothing but it's equivalent to a few minutes of daytime power production.  If you have any significant inductive load like a ventilation fan that is cooling your house overnight with outside air this will be lost in the noise.

Power factor is an issue when you have to distribute over a long distances picking up big distribution and transformer losses.  Going from your roof to your garage isn't a big deal.

If Dave gets a battery system this will be easy to verify: put a current clamp around the DC battery lead, then measure the draw in the middle of the night.  Use the manual AC disconnect on the solar feed and see how much the battery draw changes with and without the inverters.  I'd certainly be interested to see my handwaving guess verified.

Correct.  battery/inverter swithcing losses + I2R losses for the solar install radial.
And only a problem if you have an isolated battery system. Enphase have confirmed that a battery system would not deliver the apparent current if it's grid connected.

[bdunham7]

Enphase have confirmed that a battery system would not deliver the apparent current if it's grid connected.

Which is interesting because here, with the gradual introduction of Rule 21, solar inverters are required to supply reactive power as needed.  This means they are a sort of active-VAR and assume some of the same burden that the utility generators have.  The capacitance in the standby mode could be advertised as a passive VAR feature of dormant inverters, which like solar itself would be a net positive until there are too many of them.  My area is sprinkled with switchable capacitor banks on the utility poles so I assume there is still a great need for VAR correction.

Scroll down to the Dynamic Voltage/VAR section and you'll see that new inverters here are required to provide up to 62% of their output as reactive power, depending on conditions.

https://www.openintl.com/california-rule-21-interconnection/

[ejeffrey]

Enphase have confirmed that a battery system would not deliver the apparent current if it's grid connected.

Which is interesting because here, with the gradual introduction of Rule 21, solar inverters are required to supply reactive power as needed.  This means they are a sort of active-VAR and assume some of the same burden that the utility generators have.  The capacitance in the standby mode could be advertised as a passive VAR feature of dormant inverters, which like solar itself would be a net positive until there are too many of them.  My area is sprinkled with switchable capacitor banks on the utility poles so I assume there is still a great need for VAR correction.

Scroll down to the Dynamic Voltage/VAR section and you'll see that new inverters here are required to provide up to 62% of their output as reactive power, depending on conditions.

https://www.openintl.com/california-rule-21-interconnection/

Interesting. I don't quite get how the "absorbing / supplying reactive power to deal with over/undervoltage" works, but this seems like an obviously necessary and helpful step.  It also includes frequency stabilization, transient ridethrough without triggering islanding, and a bunch of other stuff.

Of course the utilities still want to reduce the feed in price down to next to nothing even during demand imbalance and also charge you for electricity you generate and consume locally, even while mandating that solar installations help improve grid stability...

[bdunham7]

Of course the utilities still want to reduce the feed in price down to next to nothing even during demand imbalance and also charge you for electricity you generate and consume locally, even while mandating that solar installations help improve grid stability...

Fortunately that rather extreme position on the part of the utilities hasn't been accepted in California, but other states have adopted plans like that.  And if you try to go off-grid, they'll do things ranging from denying your building permit to taking your kids away. 

I think the first-stage simple implementation simply assumes that current is lagging during sags and supplying some reactive current to the local grid will reduce the total distribution inflow to that section of the grid, which reduces voltage drop in that leg of the distribution network.  Or something like that.  I'd like to see the detailed explanation.

[David Hess]

Fortunately that rather extreme position on the part of the utilities hasn't been accepted in California, but other states have adopted plans like that.  And if you try to go off-grid, they'll do things ranging from denying your building permit to taking your kids away.

Usually the law requires that the house have a power grid hookup to be considered habitable.

I think the first-stage simple implementation simply assumes that current is lagging during sags and supplying some reactive current to the local grid will reduce the total distribution inflow to that section of the grid, which reduces voltage drop in that leg of the distribution network.  Or something like that.  I'd like to see the detailed explanation.

That would work for correcting power factor at the power meter where it can be measured.  If it was used to correct the power factor of a remote load, then it would cause poor power factor on the line to that point.

Online UPSes which have power factor correction do this for their own loads.  You can plug a 0.6 power factor load into an online UPS which has power factor correction, and the line side will see a 1.0 power factor when powering that load.

[Geoff-AU]

Any modern DC string inverter with Global MPPT (Fronius Dynamic Peak Manager, SMA Shadefix, etc) will give you more energy over the long run than microinverters - due to the distributed inefficiency of the microinverters.  Even in light to moderate shading and dealing with a hard shadow or two.

The only time microinverters "win" is if you have shading so heavy that it's not economical to put a panel in that location anyway.

Has been proven many times in many tests that microinverters are simply an example of very effective FUD marketing.

But they do make it easy to make ad-hoc expansions, in the case where SWMBO has firm opinions about the roof which despite being firm, are subject to change.  Luckily I managed to put all 13kW of panels up in one go, so I went with DC strings.

[NiHaoMike]

Time shifting doesn't require storage, it requires the utility to increase or curtail other sources as needed to accommodate a 'priority' producer like solar. 

Or adjust demand to try to match production. Ohmconnect is one program that tries to do it. Adding thermal storage would be far cheaper than batteries and would do a lot in any area that has significant HVAC use.

Of course the utilities still want to reduce the feed in price down to next to nothing even during demand imbalance and also charge you for electricity you generate and consume locally, even while mandating that solar installations help improve grid stability...

At that point, if selling back is not going to net a positive, I would just put in a DIY zero export system.

Usually the law requires that the house have a power grid hookup to be considered habitable.

What would the Amish do? Even though some have given in and decided to use some modern technology, I'd imagine there are still some who are sticking with how they did it in the old days.

[EEVblog]

Any modern DC string inverter with Global MPPT (Fronius Dynamic Peak Manager, SMA Shadefix, etc) will give you more energy over the long run than microinverters - due to the distributed inefficiency of the microinverters.  Even in light to moderate shading and dealing with a hard shadow or two.
The only time microinverters "win" is if you have shading so heavy that it's not economical to put a panel in that location anyway.
Has been proven many times in many tests that microinverters are simply an example of very effective FUD marketing.
But they do make it easy to make ad-hoc expansions, in the case where SWMBO has firm opinions about the roof which despite being firm, are subject to change.  Luckily I managed to put all 13kW of panels up in one go, so I went with DC strings.

That's the thing with my situation. I already have 14 x Enphase microinverters and the Envoy system.
If I want to consolidate into one system then I either have to expand the Ephase system or scrap it entirely and move back to string inverters. Or expand with another string inverter, and stick with having two separate systems.
 
Also, DC string fires a real thing, so potential safety advantages there with the AC micro inverters.
Also, if one panel fails for whatever reason is doesn't take down the string. Plus from a data point of view you can get individual graphs from each panels which is prety cool. Not essential of course, but cool.

As you can see here, I am getting shading in winter in the morning where I want the new system to go. I summer time there is another tree you see on the left there that will likely also shade it.

[EEVblog]

Enphase have confirmed that a battery system would not deliver the apparent current if it's grid connected.

Which is interesting because here, with the gradual introduction of Rule 21, solar inverters are required to supply reactive power as needed.  This means they are a sort of active-VAR and assume some of the same burden that the utility generators have.  The capacitance in the standby mode could be advertised as a passive VAR feature of dormant inverters, which like solar itself would be a net positive until there are too many of them.  My area is sprinkled with switchable capacitor banks on the utility poles so I assume there is still a great need for VAR correction.

Scroll down to the Dynamic Voltage/VAR section and you'll see that new inverters here are required to provide up to 62% of their output as reactive power, depending on conditions.

https://www.openintl.com/california-rule-21-interconnection/

Interesting. The Enphase inveretrs do indeed have an active VAR, but I'm not if that's continuously variable or fixed at install, but it can be varied +/- 0.2 I think.

[David Hess]

Usually the law requires that the house have a power grid hookup to be considered habitable.

What would the Amish do? Even though some have given in and decided to use some modern technology, I'd imagine there are still some who are sticking with how they did it in the old days.

The Amish would have lived and built their house where it was not a requirement.  Usually it comes up when someone wants to convert to solar power with a battery system and disconnect entirely from the grid.  With a suitable investment it is feasible, but usually not legal.

[NiHaoMike]

Also, DC string fires a real thing, so potential safety advantages there with the AC micro inverters.

You can get an arc fault detector like the PVAF-T2.

The Amish would have lived and built their house where it was not a requirement.  Usually it comes up when someone wants to convert to solar power with a battery system and disconnect entirely from the grid.  With a suitable investment it is feasible, but usually not legal.

Wouldn't a workaround be to just put in a transfer switch and leave it in the inverter position?

[EEVblog]

I got a response from Enphase, and their system can indeed do active VAR control.

All of the Enphase microinverters are totally capable of supplying any amount of reactive power.   This means that we can keep one inverter running at nighttime and get this one inverter to offset all the capacitive reactive current of all the shutdown inverters.   In this way we can end up with zero reactive current at a system level.   We could do this at an individual inverter level, but this would mean keeping all the inverters running 24 hours a day and it is more efficient to do this at a system level using just one inverter.

The ability for our microinverters to generate reactive current is part of the "advanced grid functionality" required by most jurisdictions before inverters can be connected to the grid.  Accordingly, your power utility company will dictate to Enphase how they want our system to behave,  and this includes the nighttime behavior.  Some utility companies want our solar system to zero out the reactive current at nighttime and if this is the case, we will program your inverters to do that (at a system level).

For most utility companies, common sense prevails, and they see the mutual advantage to them and the system owner of simply allowing a capacitive reactive nighttime behavior.

[Someone]

The Amish would have lived and built their house where it was not a requirement.  Usually it comes up when someone wants to convert to solar power with a battery system and disconnect entirely from the grid.  With a suitable investment it is feasible, but usually not legal.

Wouldn't a workaround be to just put in a transfer switch and leave it in the inverter position?

A large part of the economic justification for going off grid is not paying for a service you dont want/use. There are similar odd laws around connection to town water/sewer. In some places if the "essential" service runs past your property you are required to pay for it even if you dont use it.

[David Hess]

The Amish would have lived and built their house where it was not a requirement.  Usually it comes up when someone wants to convert to solar power with a battery system and disconnect entirely from the grid.  With a suitable investment it is feasible, but usually not legal.

Wouldn't a workaround be to just put in a transfer switch and leave it in the inverter position?

You could do that, but you are still paying for the hookup to the power grid whether you use it or not.

[bdunham7]

I got a response from Enphase, and their system can indeed do active VAR control.

All of the Enphase microinverters are totally capable of supplying any amount of reactive power.   This means that we can keep one inverter running at nighttime and get this one inverter to offset all the capacitive reactive current of all the shutdown inverters.   In this way we can end up with zero reactive current at a system level.   We could do this at an individual inverter level, but this would mean keeping all the inverters running 24 hours a day and it is more efficient to do this at a system level using just one inverter.

The ability for our microinverters to generate reactive current is part of the "advanced grid functionality" required by most jurisdictions before inverters can be connected to the grid.  Accordingly, your power utility company will dictate to Enphase how they want our system to behave,  and this includes the nighttime behavior.  Some utility companies want our solar system to zero out the reactive current at nighttime and if this is the case, we will program your inverters to do that (at a system level).

For most utility companies, common sense prevails, and they see the mutual advantage to them and the system owner of simply allowing a capacitive reactive nighttime behavior.

I see your issue got bumped up to someone that appears to know what they are talking about.

[Towger]

In this part of the world we get SFA for feeding power back into grid.  Often new systems in order of preference will change over from: Supply house, charge EV, heat water and charge a battery. The last option is to feed back into the grid.

[tszaboo]

I agree that Australia does not have "net metering" as the US define it, but Australia reuses the term and that Wikipedia article tries to shoehorn all the different ways the term is used into a single thing. So trying to use the term "net metering" in an international forum/context immediately fails to convey any real meaning unless you want to constantly refer to the specific jurisdiction/rules/explanation.

... p.s. "net metering" that is 1:1 time shifting is broken, it doesn't price storage. For all the free market bluster of the US they sure like to add bizzare bureaucratic distortions to a free market (electricity, corn, steel, etc).

Net metering as a term makes sense, you just have to define the period of it.
It can be yearly, when your net production over a year is substracted from your net consumption.
Or 15 minutes based, which is the typical "momentary" measurement, as far as I know, they will not go lower time resolution than that. This is often called Time of Use Net metering.

[Someone]

I agree that Australia does not have "net metering" as the US define it, but Australia reuses the term and that Wikipedia article tries to shoehorn all the different ways the term is used into a single thing. So trying to use the term "net metering" in an international forum/context immediately fails to convey any real meaning unless you want to constantly refer to the specific jurisdiction/rules/explanation.

... p.s. "net metering" that is 1:1 time shifting is broken, it doesn't price storage. For all the free market bluster of the US they sure like to add bizzare bureaucratic distortions to a free market (electricity, corn, steel, etc).

Net metering as a term makes sense, you just have to define the period of it.
It can be yearly, when your net production over a year is substracted from your net consumption.
Or 15 minutes based, which is the typical "momentary" measurement, as far as I know, they will not go lower time resolution than that. This is often called Time of Use Net metering.

Except the smart meters in Australia (thus likely most of the world since these arent unique regional designs) are instantaneous, and report accumulated incoming and outgoing power (as the single meter sees it) separately over the requested billing/accounting duration. "Net Metering" is a holdover from mechanical/dumb metering days when there was no practical option to accumulate the two independently (hence stupid things like fully gross metered installations, with no self consumption). The 15 common minute reporting period is not a pre-summed import+export total, but two separate values accumulated in separate counters/fields. Even the consumer material explains this:
https://www.solarquotes.com.au/good-solar-guide/net-metering/

[EEVblog]

I agree that Australia does not have "net metering" as the US define it, but Australia reuses the term and that Wikipedia article tries to shoehorn all the different ways the term is used into a single thing. So trying to use the term "net metering" in an international forum/context immediately fails to convey any real meaning unless you want to constantly refer to the specific jurisdiction/rules/explanation.

... p.s. "net metering" that is 1:1 time shifting is broken, it doesn't price storage. For all the free market bluster of the US they sure like to add bizzare bureaucratic distortions to a free market (electricity, corn, steel, etc).

Net metering as a term makes sense, you just have to define the period of it.
It can be yearly, when your net production over a year is substracted from your net consumption.
Or 15 minutes based, which is the typical "momentary" measurement, as far as I know, they will not go lower time resolution than that. This is often called Time of Use Net metering.

Except the smart meters in Australia (thus likely most of the world since these arent unique regional designs) are instantaneous, and report accumulated incoming and outgoing power (as the single meter sees it) separately over the requested billing/accounting duration. "Net Metering" is a holdover from mechanical/dumb metering days when there was no practical option to accumulate the two independently (hence stupid things like fully gross metered installations, with no self consumption). The 15 common minute reporting period is not a pre-summed import+export total, but two separate values accumulated in separate counters/fields. Even the consumer material explains this:
https://www.solarquotes.com.au/good-solar-guide/net-metering/

I've still got dumb net metering.

[EEVblog]

So it looks like I can get Enphase IQ7A's for $180ea, that's not bad.
The new IQ8A's are $235ea
No idea what panels I'll get, as LG are goneski, but I'd happily buy old stock if anyone has any.

[bdunham7]

So it looks like I can get Enphase IQ7A's for $180ea, that's not bad.
The new IQ8A's are $235ea

AUD$ ?  That would be pretty cheap IIRC. 

[EEVblog]

So it looks like I can get Enphase IQ7A's for $180ea, that's not bad.
The new IQ8A's are $235ea

AUD$ ?  That would be pretty cheap IIRC.

Yep, AUD. Seems quite cheap. Cheaper if I buy 20

[richard.cs]

Net metering as a term makes sense, you just have to define the period of it.
It can be yearly, when your net production over a year is substracted from your net consumption.
Or 15 minutes based, which is the typical "momentary" measurement, as far as I know, they will not go lower time resolution than that. This is often called Time of Use Net metering.

On a short enough timescale all metering is net metering. i.e. if you export for a few cycles and import for a few cycles alternately the meter measures net. EU meters at least have a 3600 J buffer that you can freely borrow from the grid and return. I have a controller for a water heater that works that way, integrates energy use and does bang-bang control of the heater to stay within a window about 1 kJ wide giving zero metered import/export without actually needing to modulate the heater power. On a mechanical meter it rocks the wheel backwards and forwards without incrementing the counter.

Edit: fixed typo

[EEVblog]

Just realised that my eixsting Enphase system has two Q relays and doesn't seem to have room for any more.
They are 4.8KVA rated each, and each one currently only has 7 x 295VA IQ7+ inverters on them.
https://www4.enphase.com/sites/default/files/downloads/support/Q-Relay-DS-EN-AU.pdf
That leaves me 2735VA capacity left over for each Q relay.
If I get the IQ7A's at 366VA each that gives me an extra 7 panels per relay in theory.
But I think there is some derating going on here because my existing system needed two Q relays when the total VA was only 14x295VA=4130VA
So I'm not sure how that works.
I can of course install an additional box with an extra Q relay if needed, it's just, messy.

[fourtytwo42]

Net metering as a term makes sense, you just have to define the period of it.
It can be yearly, when your net production over a year is substracted from your net consumption.
Or 15 minutes based, which is the typical "momentary" measurement, as far as I know, they will not go lower time resolution than that. This is often called Time of Use Net metering.

On a short enough timescale all metering is net metering. i.e. if you export for a few cycles and import for a few cycles alternately the meter measures net. EU meters at least have a 3600 J buffer that you can freely borrow from the grid and return. I have a controller for a water heater that works that way, integrates energy use and does bang-bang control of the heater to stay within a window about 1 kJ wide giving zero metered import/export without actually needing to modulate the heater power. On a mechanical meter it rocks the wheel backwards and forwards without incrementing the counter.

Edit: fixed typo

I think this is highly dependant upon the exact model of smart meter involved, I have heard several stories where this method typically used by grid frequency burst controllers does not work and newer more expensive high frequency pwm techniques have had to be used instead.

[richard.cs]

I think this is highly dependant upon the exact model of smart meter involved, I have heard several stories where this method typically used by grid frequency burst controllers does not work and newer more expensive high frequency pwm techniques have had to be used instead.

A few years ago I went digging around in the metering standards trying to work out what would happen when my meter got upgraded and it certainly appeared that there was a deliberate 1 Wh deadspot mandated. I think it was referred to as an "anti creep" feature.

Edit, a very quick search found this, which suggests most but not all meters implement it: https://learn.openenergymonitor.org/pv-diversion/background/meters

[rowlandcrew]

I have just gone through an incremental upgrade to try an ensure no grid draw when charging the electric car while powering all the normal stuff.  Some observations seem generally applicable:
1) supposedly, and verifiable, the panels to purchase should have bypass diodes so shading issues are limited to the shaded panels.
2) for most system sizes, likely the cheapest way through would be 400V strings going into a reasonable multiple inverters, including possibly buying broken or used solaredge inverters (refer to mppt comment below).
3) for 2022, buy used 400 watt panels.
4) If you find used solaredge optimizers and want to try panel level mppt, some Pxxx "excess" box lots are cheap, there is no need to be eco-system tied to solaredge inverters. Just buy either a solaredge SMI or the SE1000key to effectively turn off the proprietary connection and use whatever inverter you want.
5) Given the cost of the above, it seems hard to justify microinverters, but if they can be found cheap, then go for them.
6) Most optimal to have an installed solar system that is of the type you want (grid tie, or whatever) because increments  or mods you can do yourself far more efficiently than subcontracting, with only the oversignt you want.
7) the recent film capacitor debate is relevant. It appears common to use an output inductor and an X2 cap to limit noise and improve PF. My experience is the cap suffers from incremental "burn in" (I tried epcos). At least for solaredge I have not seen any semiconductor burn out in failed inverters, just caps and mov's.  Onboard Inverter monitoring appears hyper sensitive to inappropriate LC filtering, probably because of utility-regulator requirements, which may happenstance improve semiconductor survivability.  The solaredge method is to quickly open internal relays.  See photo for example of a "burn in" event that was managed by the solaredge computer.  the dropout of one of my 3 paralleled inverters lasts for about 1 minute, does not reboot the inverter, has occured 5 times, once a day, since install of a new X2 cap a week ago.
8)  I would like to see some continuous scope monitoring of X2 caps with captured self healing events to compare. The data must be out there somewhere.   

[EEVblog]

I have just gone through an incremental upgrade to try an ensure no grid draw when charging the electric car while powering all the normal stuff.  Some observations seem generally applicable:
1) supposedly, and verifiable, the panels to purchase should have bypass diodes so shading issues are limited to the shaded panels.
5) Given the cost of the above, it seems hard to justify microinverters, but if they can be found cheap, then go for them.

My issue is that I already have the Enphase microinverters, so from a system standpoint it makes sense to pay a bit more and standardise on them instead of getting yet another string inverter system and yet another monitor and data collection system etc.

Debating whether or not to just buy the parts myself and install it all myself, and then get an electrican to do the final mains hookup. Or just pay more and have it all done in a day as a system job.

[bdunham7]

My issue is that I already have the Enphase microinverters, so from a system standpoint it makes sense to pay a bit more and standardise on them instead of getting yet another string inverter system and yet another monitor and data collection system etc.

Two additional minor things to think about:

1) My ten-year old system has apparently developed an issue with one panel or microinverter.  I haven't figured it out yet, but it is likely to be a failing inverter or (less likely) a rat has chewed a cable or there is a bad connection.  Until I get time and reasonable weather to get up there and have a look, my system is down to 29/30ths of capacity.  So I'll get to it when I get to it.  Not all Enphase systems are like this. Some, like yours, do have single points  of total failure like the relays, but panels, inverters and the Envoy hub aren't in that group.

2) The custom inverter cabling on the Enphase setup is a significant additional expense, so even if you already have the Envoy, etc, you have to figure in the wiring on a per-panel basis.  Did you get a quote for that?

[rowlandcrew]

"My issue is that I already have the Enphase microinverters, so from a system standpoint it makes sense to pay a bit more and standardise on them instead of getting yet another string inverter system and yet another monitor and data collection system etc."

Sounds like you prefer uniform circuit layout, but I wonder how much this is so as a function of you spending extra dollars for uniformity.  As for multiple systems, I simply added the incrementally added AC production loop through my data logger. yes this gives a sum, but it is immediately apparent if one of the inverters is down or, with my one second time resolution I can see one inverters' capacitor healing.  My main benefit to a data logger is managing home use times. while not as fun as seeing all the technical details, the focus quickly becomes power flow cost. 

Your "starting" solar asset is whatever is installed (remaining) after raising the roof (after dismantling parts of your solar system).  Your valuation of this is different than an installer because you care about additional issues.  Paying someone to do the work leans toward uniformity because installers only like uniformity.  this installer preference is to their benefit, not yours.  The equation for cost is personal-- a sum of:   your time, clock time, opportunistic parts bargains, fun, the benefit of last minute upgrade opportunities, where to put battery, better installation practices that contractors dont care for.....   

I did not want to buy additional conduit, monitoring, etc.  But I did need more racking, some conduit, as a minimum to get to the nearest tie-in point.  The minimalist plan chosen was to slip in three more wires into the nearest installed infrastructure.  this did save parts, time, money, for me.  As far as utility connections, if they even looked, they only see a little more power showing up.  Example marginal stuff to add would be larger conduit with spare wires that can carry DC or AC (for later use), better access to the hardware (layout) because at some point something will die.  One item I did not go for was the newer spec solar wire, because of cost (copper, diameter, and later planned upgrade).  they have 1500V wire that opens the future for HV panels and longer strings, both of which are destined to reduce total cost.

If you are raising your roof, this sounds like larger scale modifications will have marginal costs.  With a small roof, doubling each panel power output (trade old for new panels) is the most effective way to reduce power purchase up to the point where you produce and sell twice what you buy ($sell/$buy).  As the utility reduces payments, this requires rebalancing the cost for a battery against using the grid as your battery. 

[NiHaoMike]

Just realised that my eixsting Enphase system has two Q relays and doesn't seem to have room for any more.
They are 4.8KVA rated each, and each one currently only has 7 x 295VA IQ7+ inverters on them.
https://www4.enphase.com/sites/default/files/downloads/support/Q-Relay-DS-EN-AU.pdf
That leaves me 2735VA capacity left over for each Q relay.
If I get the IQ7A's at 366VA each that gives me an extra 7 panels per relay in theory.
But I think there is some derating going on here because my existing system needed two Q relays when the total VA was only 14x295VA=4130VA
So I'm not sure how that works.
I can of course install an additional box with an extra Q relay if needed, it's just, messy.

Does the Q relay do something with the current flowing through it (e.g. measure it) or could you wire in a contactor to switch the additional strings?

[EEVblog]

"My issue is that I already have the Enphase microinverters, so from a system standpoint it makes sense to pay a bit more and standardise on them instead of getting yet another string inverter system and yet another monitor and data collection system etc."

Sounds like you prefer uniform circuit layout, but I wonder how much this is so as a function of you spending extra dollars for uniformity.  As for multiple systems, I simply added the incrementally added AC production loop through my data logger. yes this gives a sum, but it is immediately apparent if one of the inverters is down or, with my one second time resolution I can see one inverters' capacitor healing.  My main benefit to a data logger is managing home use times. while not as fun as seeing all the technical details, the focus quickly becomes power flow cost. 

[EEVblog]

Does the Q relay do something with the current flowing through it (e.g. measure it) or could you wire in a contactor to switch the additional strings?

It's just there to isolate the system. Legal requirement. Each one has some spare current handling capacity.

[NiHaoMike]

I was thinking to have the Q relay switch some contactors and then use the contactors to switch as many strings as you want.

[EEVblog]

Change of plans.
4 big panels (e.g. 450W-500W) on the pergola roof out the back going into a Fronius inverter to replace the existing SunnyBoy.
Will need a two string inverter, one the existing 12x250W panels, and the new 4x500W-ish panels. The existing SunnyBoy is maxed out at 3kW already even though it has another available string input.
Will give us a nice peak power boost during the day to charge the EV year round without too much cost and impact the visual appeal of the front roof.

Don't know about mounting the panels on the pergola colourbond roof sheets though? Anyone done this?
Could even have a go at mounting them myself maybe.

[EEVblog]

Someone on Twitter pointed me to these corregated solar rail mounts:
https://legacy.k2-systems.com/en-AU/pv-mounting-systems/singlerail-system

Looks good, I think I'll DIY these on the pergola.

[Ed.Kloonk]

Someone on Twitter pointed me to these corregated solar rail mounts:
https://legacy.k2-systems.com/en-AU/pv-mounting-systems/singlerail-system

Looks good, I think I'll DIY these on the pergola.

They are in QLD. I don't think there's very much in the way of suppliers in NSW.

[EEVblog]

Someone on Twitter pointed me to these corregated solar rail mounts:
https://legacy.k2-systems.com/en-AU/pv-mounting-systems/singlerail-system

Looks good, I think I'll DIY these on the pergola.

They are in QLD. I don't think there's very much in the way of suppliers in NSW.

They don't ship?

UPDATE: i tried to register for the software and it's only for installers it seems, not for private use. Seems I can't buy their stuff 

[Ed.Kloonk]

Someone on Twitter pointed me to these corregated solar rail mounts:
https://legacy.k2-systems.com/en-AU/pv-mounting-systems/singlerail-system

Looks good, I think I'll DIY these on the pergola.

They are in QLD. I don't think there's very much in the way of suppliers in NSW.

They don't ship?

I prefer to pick up where possible esp when shipping costs are involved or am dubious of the delivery ability. I'm sure they ship, and I'd be interested to know if they do small quantity.

Edit. Ah, yeah. The mob near Campbelltown told me the same last year. They just aren't interested.

[EEVblog]

I found this Fronius Primo GEN24 that does a 3kW small scale backup that would be ideal for what I had in mind of backing up just the fridges and maybe light and some other things in case of power failure. Without the hassle of having a full house AC backup system.
Would support both my existing 3kW string and the new 4x500W pergola system.

https://www.fronius.com/en/solar-energy/installers-partners/products-solutions/residential-energy-solutions/gen24plus-inverter-with-flexible-backup-power#anc_keyfeatures

[rowlandcrew]

here is a scaleable microgrid isolation device that fundamentally is a directional contactor to install at the service entrance.  the idea is to have some battery and be able to defeat utility curtailment of your solar production, yet you can suck as much grid power as you want. 

[EEVblog]

here is a scaleable microgrid isolation device that fundamentally is a directional contactor to install at the service entrance.  the idea is to have some battery and be able to defeat utility curtailment of your solar production, yet you can suck as much grid power as you want.

Yes, that's how most battery backup capable inverters work, they need a seperate box.
The Fronius one is nice in that for partial backup it doesn't need any external box, it's all built in.

If I have this correct, the Fronius Primo GEN24 will:
a) Give me battery backup for regular use during the night, scaleable as needed with the modular BYD battery solution.
b) If the power fails it will give me an automtic backup on an isolated power point, up to 3kW of power.
c) Will continue to operate independently during power failure to provide grid isolated solar+battery->power point during the day, and Battery-Powerpoint during the night. It will even work without a battery system during the day.
d) Optional full house backup if I install extra boxes on the grid side.

This means that durign power failure my 5kW enphase system is useless, and only my old 3kW+new install will work, but that's more enough for emergencies. With 3kW max it can even charge my EV.

[rowlandcrew]

from the specs, it is not clear if this fronius will synthesize grid to cause the other grid tie inverter to work when the grid is down.  It may do so, and you want it to do so, so you get all solar output when the grid is down. the schneiders do synthesize grid.  there is a fronius gen24 6kW version, larger than the one you identified, with two mppt inputs.  you could sell your enphase microinverters to pay for the larger fronius.  you could sell your 250w panels and upgrade to more 450 watt units and then make money selling power to your utility.  (do they pay?)

[EEVblog]

from the specs, it is not clear if this fronius will synthesize grid to cause the other grid tie inverter to work when the grid is down.  It may do so, and you want it to do so, so you get all solar output when the grid is down. the schneiders do synthesize grid.  there is a fronius gen24 6kW version, larger than the one you identified, with two mppt inputs.  you could sell your enphase microinverters to pay for the larger fronius.  you could sell your 250w panels and upgrade to more 450 watt units and then make money selling power to your utility.  (do they pay?)

I would get the 6kW version.
It can work on full house backup but you need extra devices to isolate the grid. So it should be possible to get the Enphase ones to work as well when the power is down, as they would detect the Fronius gne output as the mains.
But the simpler emeregncy 3kW backup output does not need these extra grid isolation devices, and that is good enough for an emergency backup. So no real need to have the Enphase work as well.

I make 8c/kWh selling power back to the grid, i.e. practically nothing. I want to use as much as I can.

[EEVblog]

If anyone has any links for cheap 500W+ panels in Australia please let me know.

[Ed.Kloonk]

Don't know about mounting the panels on the pergola colourbond roof sheets though? Anyone done this?
Could even have a go at mounting them myself maybe.

What I did on my one on my corrugated iron shed roof was use the plain old tile roof bracket and fixed them with the 14(?) gauge 90mm hex screws and sandwiched the bracket to the roof with the big rubber washers that come with the screws for the clear corrugated sheets. If you put enough brackets in, it's fine. Endured a few years of interesting Sydney weather, still good as gold. There are a few rules regarding bracket minimums and maximums if running it HV. It should be earth strapped.

Get some 40mm x 25mm square hollow channel or similar from Capral. For runs over 6m, I just cleated it with the same material. Use Nylocs on all the nuts. Drill the panel mounting holes on the ground before you put it on the roof. I folded a piece of stainless steel for the isolator switch rain/sun cover.

 

What I've got to do is change the angle of mine as it's too low in winter (~13 degrees). According to Hoyle, the optimum for Sydney is 29 degrees. But I wonder if that figure is based on a perfect north facing roof. My one is positioned about 30 degrees more toward the morning sun part of the sky so I trying to decide if the 29 number should be a bit higher. Works fine in spring, summer and autumn at the low angle, of course.

I intend to fashion some stems that will attach to the brackets on the high side to lift it and am yet to decide what I'll use for the pitch angle change shims so the rails present square to the panels.

[Geoff-AU]

from the specs, it is not clear if this fronius will synthesize grid to cause the other grid tie inverter to work when the grid is down.

If it works, it's not intentional.  During offgrid backup power operation it runs at 53Hz to try and encourage other devices to disconnect.

[EEVblog]

EcoFlow are sending me this Delta Pro 3.1kWh battery.
https://au.ecoflow.com/products/delta-pro-portable-power-station, it's on the slow boat.
I was think this would power the fridges via dedicated power lines from the mains output and then have this charge from the mains during daylight hours which would of course come from the solar on the roof.
At night the energy goes into powering the fridges.
They also sent me a portable 400W panel, but that not really for roof use.

[David Hess]

I have studied a few of that type of battery product now.  I wish they were designed for cell replacement.

[EEVblog]

Ok, this is getting nuts. I'm being inundated with solar/battery companies.
Enphase want to help out with system expansion and storage, whatever I need.
Fronius actually got back to me today and are keen for the hybrid inverter or whatever.
I just got sent an EcoFlow 3.6kWh DeltaPro battery and portable solar panels.
And Holymils just emailed about a collab for microinverters and storage or whatever.

WTF do I do? 

[tszaboo]

Ok, this is getting nuts. I'm being inundated with solar/battery companies.
Enphase want to help out with system expansion and storage, whatever I need.
Fronius actually got back to me today and are keen for the hybrid inverter or whatever.
I just got sent an EcoFlow 3.6kWh DeltaPro battery and portable solar panels.
And Holymils just emailed about a collab for microinverters and storage or whatever.

WTF do I do? 

I envy your issues, that companies want to send free stuff for the advertisement. Stuff that practically makes money.

[EEVblog]

I envy your issues, that companies want to send free stuff for the advertisement. Stuff that practically makes money.

Not entirely free, but nice perks of the trade.

Anyway, Enphase said I could have microinverters for the existing Sunnyboy 12x250W panel system if I wanted, but I don't see the point in that because it would cost a fair bit to install and it doesn't really give me any extra power output. Maybe just a smidge more when shaded.
So I'm still thinking 4 new panels on the pergola and some high power Enphase micro inverters as a start. Install cost minimal and I have spare capacity on my existing Enphase Q relays

The Fronius hybrid inverter, once again nice, but no additional power output just by doing that. Zero install cost to replace the Sunnyboy with that though, and adds option for a battery, only downside is it can only use BYD batteries, no DIY solution as far I'm aware.

[gf]

Did you already check/consider Victron Multiplus II as hybrid/off-grid inverter (which is intended for 12/24/48V batteries, enablig low-cost DIY battery storage), AC coupling the existing Enphase inverters, and connecting the 4 new panels via MPPT charge controller(s) to the DC battery bus? AFAIK, Enphase inverters can be throttled from the Multiplus via frequency shifting when the grid is unavailable, enabling also AC-coupled off-grid operation (see Enphase TECHNICAL BRIEF – 02032020), granted that a Multiplus model >= 5kVA is used in order that it can deal with 5kW AC coupled solar power.

[Ed.Kloonk]

Victron is a bit hard to be taken seriously here in OZ due to the price and supply problems.

For fan bois.

[EEVblog]

Did you already check/consider Victron Multiplus II as hybrid/off-grid inverter (which is intended for 12/24/48V batteries, enablig low-cost DIY battery storage)

Never heard of it. Needs a separate MPPT controller. Most others have this all built in.

[EEVblog]

Due to popular request, I ran the numbers on home battery storage for my home:

[tszaboo]

OK, so back of the napkin calculation for Tesla powerwall:
System costs 10K, Dave said it's OK for 10 years.
10 years *365 days * 10 kwh = 36500 kWh usable capacity. At 0.30AUD/kWh the system barely pays for itself (10950 AUD), by cycling it 100% DoD, every single day.
If you would include the feedback rate, probably it would be 15 years or more to pay for itself?

[tszaboo]

OK, so back of the napkin calculation for Tesla powerwall:
System costs 10K, Dave said it's OK for 10 years.
10 years *365 days * 10 kwh = 36500 kWh usable capacity. At 0.30AUD/kWh the system barely pays for itself (10950 AUD), by cycling it 100% DoD, every single day.
If you would include the feedback rate, probably it would be 15 years or more to pay for itself?

[EEVblog]

OK, so back of the napkin calculation for Tesla powerwall:
System costs 10K, Dave said it's OK for 10 years.
10 years *365 days * 10 kwh = 36500 kWh usable capacity. At 0.30AUD/kWh the system barely pays for itself (10950 AUD), by cycling it 100% DoD, every single day.
If you would include the feedback rate, probably it would be 15 years or more to pay for itself?

You'd be a fool to buy a Tesla Powerwall IMO.
It's one of hte most expensive, the least servicable, probably the last reliable (mechanical water cooling system), and it's not LiFePO.

[gf]

10 years *365 days * 10 kwh = 36500 kWh usable capacity.

When comparing battery systems, their useful life should be rather derived from the number of expected charging cycles, which may vary significantly between battery models.

[EEVblog]

Ok, so the solar upgrade IS happening in the next few weeks. Indeed it MUST happen.
Those in the supporters section know why.

Complete re-install of all panels.

I have two options, both of them involve buying at least 4 new panels + Enphase IQ8AC microinveretrs.

1) Go completely Enphase and replace all old 250W panels with new ones.
Costs about $7135 and gives me 8.88kW peak
Requires a 3rd Enphase IQ relay circuit which I don't have room in the box for, so small extra charge to add that.

2) Continue Enphase/String mix and reuse old 250W panels on the 3kW Sunnyboy inverter. Plus minor update to Enphase (4 extra panels)
Costs about $2760 and gives me 8.6kW peak

I could go zero extra cost and just replace everything I already have (14 enphase + 12 string), but I can fit 2 rows of 9 panels on the west side roof, so makes sense to expand the 14 panels I already have to 18 just to fill that side of the roof.

I could fit a few more on the east side roof, and if so I'd buy some more Enphase as I have some extra current capacity on the existing IQ relays.


So it seems like a no-brainer to reuse the old 12 x 250W panel and Sunnyboy inverter?
In either case I haven't included the install cost which is roughly the same for either solution.

[nctnico]

For option 1: why not get a single inverter (with multiple strings)? That saves half the cost (using a 10kW 3 phase inverter) compared to the Enphase AND you get more power output because from what I've read from the specs, the Enphase inverters can't deal with the full output of the solar panels. The solar panels I have on my roof are rated for 4500Wp total but I've seen them produce up to 5kW. I'm also not convinced by the IQ8 relays; I have a customer who had two of those relays burn out. The more stuff you add, the more that can break.

Prices for the panels also seem high. Over here a 400+ Wp panels costs less than 80 euro each.

Over here a setup with 27 panels + inverter would cost around 3200 euro (materials) with a maximum power delivery to the grid of 10kW.

[tszaboo]

For option 1: why not get a single inverter (with multiple strings)? That saves half the cost (using a 10kW 3 phase inverter) compared to the Enphase AND you get more power output because from what I've read from the specs, the Enphase inverters can't deal with the full output of the solar panels. The solar panels I have on my roof are rated for 4500Wp total but I've seen them produce up to 5kW. I'm also not convinced by the IQ8 relays; I have a customer who had two of those relays burn out. The more stuff you add, the more that can break.

Prices for the panels also seem high. Over here a 400+ Wp panels costs less than 80 euro each.

Over here a setup with 27 panels + inverter would cost around 3200 euro (materials) with a maximum power delivery to the grid of 10kW.

IMHO Enphase somehow managed to not be price competitive at any size. You could always find a better, more economic solution than them.

Dave, didn't you have a Hoymilles microinverter for 4 panel input? I know it would be a hassle to handle 3 different systems, but on the other hand you could make videos comparing them.
Also, for option two, you calculated the price of the inverters twice.

[EEVblog]

For option 1: why not get a single inverter (with multiple strings)? That saves half the cost (using a 10kW 3 phase inverter) compared to the Enphase AND you get more power output because from what I've read from the specs, the Enphase inverters can't deal with the full output of the solar panels. The solar panels I have on my roof are rated for 4500Wp total but I've seen them produce up to 5kW. I'm also not convinced by the IQ8 relays; I have a customer who had two of those relays burn out. The more stuff you add, the more that can break.

Because I already have a 14 panel Enphase system that I really like with everything in place.
A 10kW two string system would also be a high voltage system which is a potential fire hazard, so it would have to be a 4 string system I think if I went with that solution.
Although a 3rd option would be to abandon and sell the Enphase system (not the panels)

[EEVblog]

Ok, I ran the calcs and it seems I'm better off (or break even) with ditching the Enphase system entirely and going with a single 10kW hybrid inverter.
A Sungrow SH10RS 10kW 4 string hybrid inverter will cost $3400, but I can sell all my old enphase system and maybe get a 1/3 to 1/2 of that cost back.
Sell my old 250W LG panels, but keep my 14 x 370W LG panels and I get more usable peak power output from them then I did with the 295W enphase microinverters.
12 new Trina 415W panels are only $198 each, giving me a 10kW total peak system size.
That's the same number of panels as my old combined system, so no extra racking expense required like I would need if I wanted 10kW previously.
Then I can add Sungrow battery as required, and they are reasoanably priced IIRC.
I like the Sungrow because it's got 4 strings which adds some redundancy, possibly better MPPT, and lower string voltages. And I'd have physically 4 rows of panels (6x2 + 7x2)

Seems like the best, and possibly cheaper option, and I get a hybrid inverter I can add a battery to later. And I would have only one system instead of the messy two system solution I had before.
Oh, and I can sell my old 3kW Sunnyboy too.

[nctnico]

One more remark: when I looked at 4 string inverters, I noticed that some only have 2 MPTTs. I don't know how that works with 4 strings attached but it could be the strings are switched in series or something like that.

[EEVblog]

One more remark: when I looked at 4 string inverters, I noticed that some only have 2 MPTTs. I don't know how that works with 4 strings attached but it could be the strings are switched in series or something like that.

Thise one definitely has 4 MPPT and 4 inputs.
https://info-support.sungrowpower.com/application/pdf/2023/11/03/DS_20230824_SH8.0_10RS_Datasheet_V2_EN(AU).pdf

[nctnico]

That looks like a really nice unit 

[tszaboo]

Interesting choice. Do you have 3 phase power connection?
From what I can see on the market, for a solar system a battery connection is now more important than the actual inverter. I see way too many inverters that only work with one or two battery pack brands, and the batteries are coming with a heavy markup, making the system more expensive than competing solutions.
It would be interesting to see a larger growth of universal AC coupled battery inverters, because the big brands don't keep up with battery pricing or even technology. I mean next year we already might have Sodium home storage batteries that are cheaper than existing battery packs.

[EEVblog]

Interesting choice. Do you have 3 phase power connection?
From what I can see on the market, for a solar system a battery connection is now more important than the actual inverter. I see way too many inverters that only work with one or two battery pack brands, and the batteries are coming with a heavy markup, making the system more expensive than competing solutions.
It would be interesting to see a larger growth of universal AC coupled battery inverters, because the big brands don't keep up with battery pricing or even technology. I mean next year we already might have Sodium home storage batteries that are cheaper than existing battery packs.

Single phase, 65A grid fuse.
I like that the Sungrow batteries are stackable and IP55 outdoor rated, and they seem very common here and often on special.

[gf]

Is a 10kW inverter on a single phase allowed by regulation in Australia?
[ I ask, because here in Germany it is limited to 4.6kVA, and larger ones need to be 3-phase. ]

[EEVblog]

Is a 10kW inverter on a single phase allowed by regulation in Australia?
[ I ask, because here in Germany it is limited to 4.6kVA, and larger ones need to be 3-phase. ]

Yes, 10kW is the limit for single phase in NSW.

[nctnico]

Interesting choice. Do you have 3 phase power connection?
From what I can see on the market, for a solar system a battery connection is now more important than the actual inverter. I see way too many inverters that only work with one or two battery pack brands, and the batteries are coming with a heavy markup, making the system more expensive than competing solutions.
It would be interesting to see a larger growth of universal AC coupled battery inverters, because the big brands don't keep up with battery pricing or even technology. I mean next year we already might have Sodium home storage batteries that are cheaper than existing battery packs.

IMHO batteries are more interesting to early adopters or special cases at the moment. The home storage systems will need to mature quite a bit in order to become mainstream. Personally I'll look at storage when my (relatively cheap) PV inverter needs a replacement.

[tszaboo]

Interesting choice. Do you have 3 phase power connection?
From what I can see on the market, for a solar system a battery connection is now more important than the actual inverter. I see way too many inverters that only work with one or two battery pack brands, and the batteries are coming with a heavy markup, making the system more expensive than competing solutions.
It would be interesting to see a larger growth of universal AC coupled battery inverters, because the big brands don't keep up with battery pricing or even technology. I mean next year we already might have Sodium home storage batteries that are cheaper than existing battery packs.

IMHO batteries are more interesting to early adopters or special cases at the moment. The home storage systems will need to mature quite a bit in order to become mainstream. Personally I'll look at storage when my (relatively cheap) PV inverter needs a replacement.

Here in NL it makes no financial sense for most people at all yet. And since battery technology is evolving rapidly, we should wait with adaption to the last moment. On the other hand I can already see that a 5KWh battery pack from SOK is 1700 EUR, while a similarly sized  Solaredge (and other brand) battery pack is 3000 EUR, and Aliexpress is selling it for 1000 EUR.
So very soon we might end up with a situation, where a reputable Sodium 10KWh battery pack, covering all our needs will be ~1500 EUR, while a competing solution from our inverter manufacturer is 6000 EUR, which is a huge difference.
Even with the current prices of battery packs, with a contract which gives spot prices (like Frank energie), the battery pack could be profitable. Only, you would need to make some complicated system that works on day ahead prices and weather predictions.

[ahbushnell]

How does electrical billing work there?  We got net metering just in the nick of time.  It's gone away in California.  We have 27 kW-hr of batteries because I'm concerned about grid stability here.  Without EV's we can make all of our power.  We have two EV's now so that requires us to pull off the grid.   

[tszaboo]

How does electrical billing work there?  We got net metering just in the nick of time.  It's gone away in California.  We have 27 kW-hr of batteries because I'm concerned about grid stability here.  Without EV's we can make all of our power.  We have two EV's now so that requires us to pull off the grid.

Gee Whiz, California had 39 outages totalling 414 hours in 2022. What are you doing there?
The average power outage is 0.1/month here, averaging 20 minutes per customer per year.
If I didn't have power for 10 days in a year, I wouldn't pay power bills and we would probably have governments resigning out of shame.

[ahbushnell]

How does electrical billing work there?  We got net metering just in the nick of time.  It's gone away in California.  We have 27 kW-hr of batteries because I'm concerned about grid stability here.  Without EV's we can make all of our power.  We have two EV's now so that requires us to pull off the grid.

Gee Whiz, California had 39 outages totalling 414 hours in 2022. What are you doing there?
The average power outage is 0.1/month here, averaging 20 minutes per customer per year.
If I didn't have power for 10 days in a year, I wouldn't pay power bills and we would probably have governments resigning out of shame.

We have fires or we have fire conditions. 

[EEVblog]

How does electrical billing work there?  We got net metering just in the nick of time.  It's gone away in California.  We have 27 kW-hr of batteries because I'm concerned about grid stability here.  Without EV's we can make all of our power.  We have two EV's now so that requires us to pull off the grid.

The provider is forcing me to get a smart meter, which presumably puts me on a time based pricing system. Currently it's fixed.
Grid stability is simply not an issue in Sydney.

[.RC.]

Might be better of waiting until that solar cell plant in newcastle starts producing locally built solar panels at 1/10th the price they can make them in China.   

[Kleinstein]

I doubt the panels from Australia get much cheaper than those from China. They save a little on shipping, but pay more for labor.

It looks like not all panels are oriented the same way. This means that the peak (except for short special cloud cases) power will be less than the nominal power of the panels. One may thus get away with a lower inverter power, possibly less than the normal rule of thumb. One would still have to look how the inverter can mix the different strings.
The EV may already take up some of the peaks and shift the power use. So battery storage gets less attractive.

The smart meters not necessary mean a different pricing system. They just want to be prepared to allow different model and may not install old style meters anyway. With PV the metering is anyway a bit more complicated, counting power in both directions.  It would indeed make sense to change to a time dependent system, expecially for those with PV.

[EEVblog]

Interesting choice. Do you have 3 phase power connection?
From what I can see on the market, for a solar system a battery connection is now more important than the actual inverter. I see way too many inverters that only work with one or two battery pack brands, and the batteries are coming with a heavy markup, making the system more expensive than competing solutions.
It would be interesting to see a larger growth of universal AC coupled battery inverters, because the big brands don't keep up with battery pricing or even technology. I mean next year we already might have Sodium home storage batteries that are cheaper than existing battery packs.

IMHO batteries are more interesting to early adopters or special cases at the moment. The home storage systems will need to mature quite a bit in order to become mainstream. Personally I'll look at storage when my (relatively cheap) PV inverter needs a replacement.

Yes, probably not financially viable. Around $10k-ish for a 10kWh battery.
Assuming you store-use say 8kWh per day, that's $2.70/day, or 3703 days payback, or 10 years. About the life of the battery.

[EEVblog]

Might be better of waiting until that solar cell plant in newcastle starts producing locally built solar panels at 1/10th the price they can make them in China.   

LOL, won't happen.
AU$190ea delivered for a Trina 415W panel which is what I think I'll get. Payback for just the panels itself is a year or less. Less if I can sell the old 250W panels and at least get something for those.

[tszaboo]

Interesting choice. Do you have 3 phase power connection?
From what I can see on the market, for a solar system a battery connection is now more important than the actual inverter. I see way too many inverters that only work with one or two battery pack brands, and the batteries are coming with a heavy markup, making the system more expensive than competing solutions.
It would be interesting to see a larger growth of universal AC coupled battery inverters, because the big brands don't keep up with battery pricing or even technology. I mean next year we already might have Sodium home storage batteries that are cheaper than existing battery packs.

IMHO batteries are more interesting to early adopters or special cases at the moment. The home storage systems will need to mature quite a bit in order to become mainstream. Personally I'll look at storage when my (relatively cheap) PV inverter needs a replacement.

Yes, probably not financially viable. Around $10k-ish for a 10kWh battery.
Assuming you store-use say 8kWh per day, that's $2.70/day, or 3703 days payback, or 10 years. About the life of the battery.

Not with those prices.
https://www.au.sokbattery.com/product-page/pre-order-sok-48v100ah-lifepo4-battery-pack-ul-certified

[.RC.]

I doubt the panels from Australia get much cheaper than those from China. They save a little on shipping, but pay more for labor.

They won't,   It is a bit of a local joke involving politicians, think solar roadways style political decisions to get votes and squillion dollars given to grifters, it is only taxpayers money.

[EEVblog]

I'll be going with a Deye 5kW inverter to replace my Sunnyboy (with 12 x new 415W Trina panels). WAY more options for batteries of different types if I want to experiment with that.

Only questions remaining is, do I get two of them for a 10kW system, or save the >$2k (Deye inverter + two extra wiring to other side of house) and just reuse my existing 5kW Enphase system that is already in place and ready to hook back up?
I'm now erring toward saving the cash, which can actually buy me a smallish battery.

[EEVblog]

Not with those prices.
https://www.au.sokbattery.com/product-page/pre-order-sok-48v100ah-lifepo4-battery-pack-ul-certified

Yep, exactly, this is why I'm going with a Deye, you can get WAY cheaper batteries like this. I can get one of these effectively for "free" if a re-use my Enphase system.

[.RC.]

The provider is forcing me to get a smart meter, which presumably puts me on a time based pricing system.

Not being too familiar with this time based pricing system until reading an article this morning.  https://www.abc.net.au/news/2024-04-09/energy-companies-under-fire-over-time-of-use-rates/103655324

Would it be easy and cost effective to get a battery, charge it from mains when prices are cheap, then use it when prices are expensive in the evening?

[EEVblog]

5kW Deye hybrid inverter ordered (cheap at $1595) along wiht 12 new Trina 415W panels.
They will be in a two string 6 x 2 arrangement one either side of the roof to get both morning and afternoon sun.
Same company that sold me the inverter can also do a compaible battery for $2425 for a stackable 5kWh battery pack + $1395 for base control unit.

[Someone]

The provider is forcing me to get a smart meter, which presumably puts me on a time based pricing system.

Not being too familiar with this time based pricing system until reading an article this morning.  https://www.abc.net.au/news/2024-04-09/energy-companies-under-fire-over-time-of-use-rates/103655324

Would it be easy and cost effective to get a battery, charge it from mains when prices are cheap, then use it when prices are expensive in the evening?

Depends on the specific tariff, and the specific "cost" of your battery.

I don't know why people are all up in arms about being "forced" onto time of use tariffs, looking around retailers they're all offering fixed rate plans.

[AnthonyDsouza]

you could either move and upgrade the old 3kW system to the front roof, invest in a new Enphase system for consolidation, or simply retain the existing system. Moving the old system may offer cost savings but could lead to separate monitoring systems, while the Enphase option provides integration benefits despite being pricier upfront. Alternatively, keeping the old system might suffice if it's still functional and cost-effective. Assessing your priorities in terms of cost, integration, and performance can help you make the most suitable choice.

[EEVblog]

The plan I'm going with.
Installer came out this morning and had never heard of Deye inverters. 

[Halcyon]

How does electrical billing work there?  We got net metering just in the nick of time.  It's gone away in California.  We have 27 kW-hr of batteries because I'm concerned about grid stability here.  Without EV's we can make all of our power.  We have two EV's now so that requires us to pull off the grid.

The provider is forcing me to get a smart meter, which presumably puts me on a time based pricing system. Currently it's fixed.
Grid stability is simply not an issue in Sydney.

They should be able to tell you which tariff you'll be on. Just because you switch meters, surely they can't just force you onto time-of-use?

I deliberately wanted to switch over to time-of-use (I only pay peak pricing between 1600-2000hrs weekdays, all other times are off-peak) and it was a nightmare that took many months. I first had to get a smart meter, that was step one, but then when I did, Energy Australia just went "computer says no". Eventually the energy distributer fixed it and I was able to switch to another retailer that offered time-of-use rates. I was warned however, once I switch to TOU, I can't switch back to a fixed rate.

Ultimately, on any reasonably sunny day, I don't pay anything during peak time at all. On really cloudy days, my batteries are configured to charge off the grid between 1400-1600 to get them to 100% so I can offset the higher cost of power later in the day if the solar isn't doing much. I'm saving a significant amount by switching to TOU, which is currently 25.5c/kWh (including GST).

[EEVblog]

They should be able to tell you which tariff you'll be on. Just because you switch meters, surely they can't just force you onto time-of-use?

It's Energy Australia that is forcing the change, they own the lines and meters so they can do what they want.
My retailer (currently AGL) may or may not care it's bene changed. I'm a new fixed rate contract, so I presume that stays unless I ask for a change to a variable rate once the new meter goes in.

[EEVblog]

Installer said I don't have to upgrade the existing 4sq mm copper from the old 3kW Sunnyboy inverter, it'll still be able to do 5kW using that, just need to upgrade the fuses from 20A to 25A
New panels delivered this morning. Now all I have to do is choose a battery...

[Halcyon]

They should be able to tell you which tariff you'll be on. Just because you switch meters, surely they can't just force you onto time-of-use?

It's Energy Australia that is forcing the change, they own the lines and meters so they can do what they want.
My retailer (currently AGL) may or may not care it's bene changed. I'm a new fixed rate contract, so I presume that stays unless I ask for a change to a variable rate once the new meter goes in.

That's my understanding. I haven't heard them forcing people over to TOU when you're on fixed. In relation to the meter itself, the "Competition in metering" rules means that all new meters from December 2017 must be smart meters (or "advanced" meters, whatever that means). They've then palmed that responsibility over to the retailers. https://www.aemc.gov.au/energy-system/electricity/electricity-system/metering

In my case, when I was with EA, I requested the change to the tariff, filled out all their paperwork and eventually was told that they "can't" make the change because the system didn't allow it for existing customers. I said, OK well delete my account and start over, they "couldn't" do that either. It went through all kinds of managers and they eventually told me to change retailers, so I did.

Anyway, since then, I've switched over to Red Energy, not only are they much cheaper, the money stays in Australia instead of finding its way back to the "CLP Group".