Everyone seems so invested in this microinverters, and I still dont get it.Start with this: "Single point of failure."
I can only see the benefit for installers. When the bloody under engineered things blows upEvidence? Or is this only conjecture?
, because it is installed on the back of a hot panel,Not ideal - but I haven't studied the thermal design.
they can just send you the money back, instead of going on site and fixing your installation under warranty.Not in Australia mate! It'll get fixed - or there will be hell to pay
Everyone seems so invested in this microinverters, and I still dont get it.
Here is the warranty site:Everyone seems so invested in this microinverters, and I still dont get it.Start with this: "Single point of failure."QuoteI can only see the benefit for installers. When the bloody under engineered things blows upEvidence? Or is this only conjecture?Quote, because it is installed on the back of a hot panel,Not ideal - but I haven't studied the thermal design.Quotethey can just send you the money back, instead of going on site and fixing your installation under warranty.Not in Australia mate! It'll get fixed - or there will be hell to pay
.... and then it'll get fixed.
The way we "analyzed" the installations, was this: I was working at a company specializing in solar technology data collection. And dealing with so-called green certificates that were a government incentive. We had over a billion data points of 7000 solar installations, several experts, algorithm to detect partial shading, and very good understanding of the underlying costs. I was doing there the monitoring hardware, so not directly involved with the analysis, but the end result was clear.
Ease of installation and cost effectiveness--mine paid for themselves three years ago. I'm not sure how you are 'analyzing' installations, but here there are real-world permitting and other issues that have to be accounted for when you consider costs.
For example, the 'clipping' issue can actually be a benefit, even though a small amount of energy is lost, because it lowers the size of the wiring and circuitry required. Just as an example, using the old M215 inverters that I have, I can run 34 panels on a relatively standard electrical system. Since I have 240 watt panels and could use bigger ones, at some point the system occasionally maxes out and I 'lose' some power. However, if those inverters harvested ALL of that energy, I would not be allowed to connect 34 panels to my system because the maximum power would exceed a certain calculated metric (80% of 20% of 200 amperes if you want to know...).So you are saying that it's better that they output less power due to some local regulation that you have. :-//
Reliability--while earlier Enphase units had issues, they've been reliable for a decade now. Mine are 8 years old and still working 100% with no failures. And if one does fail, I lose 1/30 of my capacity.
Why would you not just disable export if they started charging for it ?
Also, I recommend some high power loads if they start charging you for export,
The regular IQ7 is so weak, it cannot handle the average inverters today. The IQ7+ is better, but for a 350W panel, the output is limited to 295VA.
Everyone seems so invested in this microinverters, and I still dont get it.
Why would you not just disable export if they started charging for it ?
Also, I recommend some high power loads if they start charging you for export,
dave jones do you have surge protection for your system?
:palm: Did you understand that page? Did you even READ it?Here is the warranty site:Quotethey can just send you the money back, instead of going on site and fixing your installation under warranty.Not in Australia mate! It'll get fixed - or there will be hell to pay
.... and then it'll get fixed.
https://enphase.com/en-au/support/labor-reimbursement-warranty-service
(https://enphase.com/en-au/support/labor-reimbursement-warranty-service)You have to judge for yourself, if 125 AUS is enough to drive to your place and 25 AUS is enough to get them to your roof.
So you are saying that it's better that they output less power due to some local regulation that you have. :-//
The average panel size is 350W today.
That indeed seems to be the case, very dissapointing.
I've got 370W panels, and I'm wasting 80W per panel, or 1.12kW total.
Although curiously the datasheet says it's designed for modules up to 385W, so :-//
Why would you not just disable export if they started charging for it ?
Also, I recommend some high power loads if they start charging you for export,
:palm: Did you understand that page? Did you even READ it?Not really, I have better things to do with my time, than figuring out what the warranty is somewhere else.
I'm familiar with the claimed benefits.Everyone seems so invested in this microinverters, and I still dont get it.
1) Safety, no HVDC.
2) Redundancy. If one panel or inverter goes down you only lose that one.
3) Shading, dirt, poop etc. You only lose that one panel, it doesn't impact the string.
If you want the cheapest system you wouldn't use microinverters.
That indeed seems to be the case, very dissapointing.Thats one of the issues that I'm seeing. Regular strings usually also have DC over provisioning. But that's 20% per panel, very different than 20% of an entire system.
I've got 370W panels, and I'm wasting 80W per panel, or 1.12kW total.
1) Solaredge and other DC optimizer
Thats one of the issues that I'm seeing. Regular strings usually also have DC over provisioning. But that's 20% per panel, very different than 20% of an entire system.
Why does Dave keep calling it a 5 kW system if it can technically only supply 290 VA * 14 = 4060 VA max? What am I missing here?
And as far as redundancy/reliability issues go, there's a plenty of experience to rely on. You can talk of heated capacitors all you like, but DC-string inverters have typically had a disturbingly high failure rate compared to even old micros. Read the warranty terms of each if you want to know the manufacturers take on that. And with DC optimization, the optimizer is in same place as the micro, so where's your advantage?
One thing that all three of the companies suggest I stayed away from was MicroInverters. The reasoning was always the same, they said that the Inverter was the most likely part to burn out and it's better to deal with a single Inverter than 20 of them. They also said they get extremely hot and therefore have a short lifespan. I mentioned shading and one guy replied that the panels would be set in three per series and that should eliminate most of the problems but if they still encounter a problem they would use Optimizes on the affected panels. I don't know enough about solar equipment to comment but when three different companies stare you away from something it's a done deal in my head.It could be none of them has experience with them. But to me it seems micro-inverters don't bring much to the table. They are installed in the worst place (on a hot roof) and instead of high voltage DC you now need to bring high voltage AC to the roof running at higher currents as well. IIRC the typical voltage a DC system runs at is 300V to 400V per string and for a >2000W installation you end up with several strings which each run with relatively low corrents (couple of amps). With all the panels disconnected you bring the voltages on the wiring down to safe levels (unless ofcourse you have panels with very high voltages but I have not seen those myself).
It could be none of them has experience with them.
high voltage DC you now need to bring high voltage AC to the roof running at higher currents as well.
IMHO this is more of a lack of regulations issue for HVDC wiring in general. Lower current = less energy available = less chance of fire. AC power packs quite a punch due to the energy the grid can provide.high voltage DC you now need to bring high voltage AC to the roof running at higher currents as well.
Not really a good comparison. The AC is just standard wiring protected by a breaker and has no unusual hazards. Older string systems had HVDC not so well protected, I'll leave it for others to argue that current string systems have reduced hazards.
And as far as redundancy/reliability issues go, there's a plenty of experience to rely on. You can talk of heated capacitors all you like, but DC-string inverters have typically had a disturbingly high failure rate compared to even old micros. Read the warranty terms of each if you want to know the manufacturers take on that. And with DC optimization, the optimizer is in same place as the micro, so where's your advantage?Solaredge optimizers dont have electrolytic capacitors in them, they are ceramic. I guess I dont have to go into the details, that electrolytic capacitors have a life expectancy on the datasheet. Also as I understand the marketing, its 1/3 the component count.
Why is it very different and when does it matter?In summer, the sun is shining, there is shading on a panel. Say, you have 10 panels, 350W each. Say all systems will have 20% overprovision.
Then DON'T make statements from a position of ignorance!:palm: Did you understand that page? Did you even READ it?Not really, I have better things to do with my time, than figuring out what the warranty is somewhere else.
I would be highly surprised if they didn't have an internal fuse as a last-ditch protection measure- as it's potted, any internal fault would be unrepairable so the fuse doesn't need to be replaceable.
What stops a bank of micro-inverters from roasting a failed one also on that AC bus? There's no local disconnect or fuse that I can see.
What stops a bank of micro-inverters from roasting a failed one also on that AC bus? There's no local disconnect or fuse that I can see.
Fault LED is a "DC Resistance Low, Power OFF" doesn't make sense on what that is. What power is off, grid or PV and who's got the ohmmeter lol.
In summer, the sun is shining, there is shading on a panel. Say, you have 10 panels, 350W each. Say all systems will have 20% overprovision.
The DC system with optimizer will output 80% of its nominal (DC) nameplate capacity, the maximum of the system.
The Enphase will output about 74%, because 9 panel will output 80% and one 20%.
A regular inverter with two strings will output 60%, as 5 panels will be 100% and the other five 20%
Honestly, beyond the technical discussions, I dont like Enphase because of the bad moves they were pulling in the past. People report that they are charged a monthly fee per panel for the monitoring. And they were charged money, when they were transferring the warranty when selling the house. Even if this only happened in the past, I just dont want to deal with a company that des these things.
After Dave's live stream last night. I was wondering about the specific microinverters used.
Enphase also makes an IQ7A inverter and I found this document on their website.
Technical Brief: https://enphase.com/sites/default/files/downloads/support/IQ7A_Vs_IQ7plus_in_Australia.pdf (https://enphase.com/sites/default/files/downloads/support/IQ7A_Vs_IQ7plus_in_Australia.pdf)
I'm no expert on the subject, but (there is always a but) it seems to me that the system is correctly spec'd.
DAVE have you actualy tested how much load your solar power system can produce in peak time,before you need to draw extra power from grid?
What stops a bank of micro-inverters from roasting a failed one also on that AC bus? There's no local disconnect or fuse that I can see.I would be highly surprised if they didn't have an internal fuse as a last-ditch protection measure- as it's potted, any internal fault would be unrepairable so the fuse doesn't need to be replaceable.
In normal operation they will be actively monitoring everything throughout the AC cycle, so will be able to shut down in the event of any abnormal situation.
According to them, yes. But they have also admitted that my system will clip on high solar insolation days. Even the 340W output IQ7A will also clip.
It's whether or no you are happy with that loss on those days. Enphase don't have higher output option available, so they have to try and justify it.
According to them, yes. But they have also admitted that my system will clip on high solar insolation days. Even the 340W output IQ7A will also clip.
It's whether or no you are happy with that loss on those days. Enphase don't have higher output option available, so they have to try and justify it.
Why fixate on the clipping? Go back and look at your own data and see how much total time your old system spent at more than 2.7kW.
BTW, I recall looking at measured insolation data at one point and I saw over 1000W/sqm in Sydney.
BTW, I recall looking at measured insolation data at one point and I saw over 1000W/sqm in Sydney.
It's entirely possible for that to happen on occasion, but keep in mind that unless it is cold, the -0.459%/K tempco of your panels will reduce the output by at least 10-12%. One of the useful features of the Enphase system is that it gives you inverter temperature, which is a fairly decent proxy for panel temperature.
I think about 1050W/m2 is pretty much the absolute limit for clear sky--and that only under specific circumstances usually only found in northern climates. However, if you have just the right combination of factors on a partly cloudy day, the limit is quite a bit higher. Of course I don't own a pyranometer so I haven't measured anything directly myself, but published literature on this all seems to agree that 1kW/m2 is the normal maximum on clear days.
https://journals.ametsoc.org/view/journals/apme/47/11/2008jamc1861.1.xml (https://journals.ametsoc.org/view/journals/apme/47/11/2008jamc1861.1.xml)
Edit: I forgot to mention altitude as a factor, so there's that too.
Take the same 80% for old 3kW system (2400W) there are total of 769 days out of 1980 days where the peak output would exceed the inverters, or 38.8% of days. That's hardly "on occasion".
Take the same 80% for old 3kW system (2400W) there are total of 769 days out of 1980 days where the peak output would exceed the inverters, or 38.8% of days. That's hardly "on occasion"."On occasion" referred to exceeding 100%, not 80%.
In this case I am talking 100%, i.e. 14x295W=4.13kW
So 38% of days my inverters can be expected to clip.
In this case I am talking 100%, i.e. 14x295W=4.13kWOK, I was referring to exceeding 100% of the panel STC rating--that's an occasional event. If you haven't read that link in my post, it refers to some interesting, and apparently not that rare, situations where irradiance can be much higher than 1kW/m2 for a short while--in one example they had 1832W/m2.
So 38% of days my inverters can be expected to clip.
Yes, I concur--according to your data, providing your new panels scale exactly as the nameplate rating (370:250), you will see some clipping on 38% of your days. And with the Enphase monitoring system you'll be able to see it quite clearly.
Why does Dave keep calling it a 5 kW system if it can technically only supply 290 VA * 14 = 4060 VA max? What am I missing here?
One thing that all three of the companies suggest I stayed away from was MicroInverters. The reasoning was always the same, they said that the Inverter was the most likely part to burn out and it's better to deal with a single Inverter than 20 of them. They also said they get extremely hot and therefore have a short lifespan. I mentioned shading and one guy replied that the panels would be set in three per series and that should eliminate most of the problems but if they still encounter a problem they would use Optimizes on the affected panels. I don't know enough about solar equipment to comment but when three different companies stare you away from something it's a done deal in my head.
We are completely off grid running about 4kw (peak) panels.
I've already seen it clip, although Enphase claim it technically didn't.
4.172kW is greater than 4.13kW (14 x 295W), so yeah, I'd say it clipped in April.
Unfortunately I won't see it easily because I've now changed the system to show the total production from both systems.
Enphase actually recommends a threshold as low as 75% (133% over-provisioning) and that only because your CEC has mandated that as a limit for some reason. They even explicitly recommend the IQ7+ for your panels over the IQ7A and they explain why. There are, in fact, good reasons to have systems with even higher overprovisioning because maximizing the usage of all available panel power is not the only valid objective, especially since panels have become so cheap.But this is actually where Enpahse fails. Panels are cheap, and you can overprovision a DC system cheaper. Or you can get a larger DC inverter cheaper. Going from a IQ7 to an IQ7A is 50% increase in the inverter cost. The IQ7 is sold for 97 EUR here, IQ7A is 149 EUR. It more expensive than most panels. Going from a 2KW SMA to a 3KW SMA is an increase of 787/1051 = 25%. Upgrading to a 4KW inverter is only 11% more expensive than the 3KW system. Or to give you an even more extreme case, going from a 4KW Solaredge to a 27KW solaredge doesn't even double the price of the inverter. Microinverters don't scale properly, the more panels you have the less sense they make.
Microinverters don't scale properly, the more panels you have the less sense they make.
Lol no. Longi solar for 110 EUR for a 370W half cut PERC panel.Microinverters don't scale properly, the more panels you have the less sense they make.
At some point that might be true and very large installations with no shading issues are less likely to use micros. But it all depends on your actual pricing. I just looked and the price of the IQ7+ is $99 if I buy them with panels. The LG panels Mr. EEVBlog was gifted go for at least $300/panel, even a cheapo 370 watt mono is $215. Yes you can get panels in the $150 range or even cheaper, but so what? Thrifted systems and products always look better from a cost-effectiveness standpoint, at least at first.
I think Dave bought the panels, and had the inverters gifted to him.
But this is actually where Enpahse fails. Panels are cheap, and you can overprovision a DC system cheaper. Or you can get a larger DC inverter cheaper. Going from a IQ7 to an IQ7A is 50% increase in the inverter cost. The IQ7 is sold for 97 EUR here, IQ7A is 149 EUR. It more expensive than most panels. Going from a 2KW SMA to a 3KW SMA is an increase of 787/1051 = 25%. Upgrading to a 4KW inverter is only 11% more expensive than the 3KW system. Or to give you an even more extreme case, going from a 4KW Solaredge to a 27KW solaredge doesn't even double the price of the inverter. Microinverters don't scale properly, the more panels you have the less sense they make.
Lol no. Longi solar for 110 EUR for a 370W half cut PERC panel.
120 for canadian solar.
For 135, made in Germany
LG... nobody sells LG, there is no market for it.
What stops a bank of micro-inverters from roasting a failed one also on that AC bus? There's no local disconnect or fuse that I can see.I would be highly surprised if they didn't have an internal fuse as a last-ditch protection measure- as it's potted, any internal fault would be unrepairable so the fuse doesn't need to be replaceable.
In normal operation they will be actively monitoring everything throughout the AC cycle, so will be able to shut down in the event of any abnormal situation.
Yes, the IQ7 system has a measurment sample and processing time of 20us.
Most domestic solar setups are not designed to work off-gridWhat stops a bank of micro-inverters from roasting a failed one also on that AC bus? There's no local disconnect or fuse that I can see.I would be highly surprised if they didn't have an internal fuse as a last-ditch protection measure- as it's potted, any internal fault would be unrepairable so the fuse doesn't need to be replaceable.
In normal operation they will be actively monitoring everything throughout the AC cycle, so will be able to shut down in the event of any abnormal situation.
Yes, the IQ7 system has a measurment sample and processing time of 20us.
Ok, I get that the microinverters analyze AC cycle really fast and all microinverters are in sync. Right?
But what is the source of AC signal? Existing grid? How all the microinverters will be in sync in an off-grid installation. Could someone enlighten me? Thanks.
But what is the source of AC signal? Existing grid? How all the microinverters will be in sync in an off-grid installation. Could someone enlighten me? Thanks.
I wonder if it is possible to trick any of these grid-tied inverter systems by disconnecting from the grid & feeding a low power sine wave inverter as a dummy emulated grid feed while the grid tied units sync up and handle the bulk of your household load.But what is the source of AC signal? Existing grid? How all the microinverters will be in sync in an off-grid installation. Could someone enlighten me? Thanks.
The grid presents a very low impedance AC signal. An off-grid system with standard (intended for grid-tie) microinverters will typically present a simulated grid signal by both sourcing and sinking current as needed, and it will communicate with the microinverters directly. The new IQ8 microinverters can be configured to run off-grid on their own somehow. I'm not sure how they handle anti-islanding requirements in that case.
I wonder if it is possible to trick any of these grid-tied inverter systems by disconnecting from the grid & feeding a low power sine wave inverter as a dummy emulated grid feed while the grid tied units sync up and handle the bulk of your household load.
I wonder if it is possible to trick any of these grid-tied inverter systems by disconnecting from the grid & feeding a low power sine wave inverter as a dummy emulated grid feed while the grid tied units sync up and handle the bulk of your household load.
If by 'trick' you mean use microinverters that are not specifically configured for off-grid use, then you need a battery-linked inverter/AC charger that can sink (to the battery) up to maximum output of your array and can also source up your maximum consumption. The sinking part is problematic in the long run because if the battery is full, there's nowhere sink the power. You then need a way to dissipate the power or curtail the array without completely shutting down your microgrid.
You'd think the microinverter would be smart enough to regulate its output down if the line voltage gets too high no? then no max sink would be needed.
Or is it more like: line voltage high -> error shutdown, have to power cycle to recover.
Ok, I get that the microinverters analyze AC cycle really fast and all microinverters are in sync. Right?
But what is the source of AC signal? Existing grid? How all the microinverters will be in sync in an off-grid installation.
For comparison,
Location: NE Scotland
System = 4kW (16 x 270W panels)
June 2021 (Summer) = 601.219kWh generated