Solar Upgrade AGAIN

[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.