My system is clipping on 12.6kw system with 7.6 inverter

[giran99]

Solar clipping on 12.6kw system with 7.6 inverter.. Trying to talk to Tesla but they are not helping or responding, keep saying inverter system can over-drive 170%
i am not sure if its worth the fight going to through court . or AG (mass Attorney general office).. any input is welcome thanks

 

[MCNE]

Yeah, that looks pretty bad, but I know there are a few threads discussing this type of issue here. Check them out, you might find some direction or approach to resolve. My system is smaller, but I have two inverters.

 

[jrweiss98020]

Yes, the inverter CAN handle the power, but it is then wasted. You should have a 10 or 11 kW inverter.

 

[Iain]

I just called Tesla ( different Solar questions) and they picked up right away. I’m not sure if you communicated via email or voice. Here’s the # (877) 798-3752

 

[BGbreeder]

Yes, the inverter CAN handle the power, but it is then wasted. You should have a 10 or 11 kW inverter.

But remember, as discussed earlier on a similar post of @giran99's. the higher inverter will gets @giran99 into a very different regulatory regime. Careful what you wish for.

 

[zƬesla]

OP's 1.7 ratio isn't good. Is it clipping year-round of only for a few weeks?

 

[giran99]

But remember, as discussed earlier on a similar post of @giran99's. the higher inverter will gets @giran99 into a very different regulatory regime. Careful what you wish for.

But remember, as discussed earlier on a similar post of @giran99's. the higher inverter will gets @giran99 into a very different regulatory regime. Careful what you wish for.

i am pushing tesla for 10kw inverter as per state law that will be ok. let's see how it goes. If they still do 10kw inverters

 

[giran99]

OP's 1.7 ratio isn't good. Is it clipping year-round of only for a few weeks?

i just got my PTO week to 10 days. i am clipping everyday if i get even 1hr of sunlight

 

[charlesj]

Yes, your DC to AC ratio is a bit high.
What was the contract for? What was the estimated yearly production? Is it generating the estimated amount for now?
The inverter will or may be able to handle such overloads year in, year out, it will not produce more than the clipped Watts. On the other hand, it will produce that max over a much longer time each day and most likely many more days during the lower sun arc times, Nov-Feb. And even longer as days are getting longer. Can you go back on that graph image and see how many hours it clipped?

 

[giran99]

Yes, your DC to AC ratio is a bit high.
What was the contract for? What was the estimated yearly production? Is it generating the estimated amount for now?
The inverter will or may be able to handle such overloads year in, year out, it will not produce more than the clipped Watts. On the other hand, it will produce that max over a much longer time each day and most likely many more days during the lower sun arc times, Nov-Feb. And even longer as days are getting longer. Can you go back on that graph image and see how many hours it clipped?

Originally order 36 solar panels with 2 inverters 7.6 and 3.8. Week before the installation, they called me and said they will change the solar panel to 32 instead of 36 . Because they don't have old 340 watt panel and new one are 395w. so i said ok. and original estimate was 12,142kwh. i think it will generate, 12000kwh
attached original order sheet

 

[charlesj]

Originally order 36 solar panels with 2 inverters 7.6 and 3.8. Week before the installation, they called me and said they will change the solar panel to 32 instead of 36 . Because they don't have old 340 watt panel and new one are 395w. so i said ok. and original estimate was 12,142kwh. i think it will generate, 12000kwh
attached original order sheet

You may generate more as it will reach peak much earlier and lasts longer each day.
Mine is about half of yours and generate 6.+ mWh year in, year out so far over ten years and don't have such a DC to AC ratio.

 

[offandonagain]

I have a similar configuration: 12.8kW panels, 7.6kW inverter, pre-PTO. I see a lot of clipping this time of year too, but when I plugged my numbers into PVWatts--comparing my 1.684 DC to AC ratio to a ratio of 1.0--it showed a mere 2% reduction in yearly output: 16.2MWh vs 16.6MWh. That didn't seem worth changing.

PVWatts will also show you the estimated DC output on an hour-by-hour basis, which will give you a sense of how tall that trimmed peak would be.

 

[giran99]

I have a similar configuration: 12.8kW panels, 7.6kW inverter, pre-PTO. I see a lot of clipping this time of year too, but when I plugged my numbers into PVWatts--comparing my 1.684 DC to AC ratio to a ratio of 1.0--it showed a mere 2% reduction in yearly output: 16.2MWh vs 16.6MWh. That didn't seem worth changing.

PVWatts will also show you the estimated DC output on an hour-by-hour basis, which will give you a sense of how tall that trimmed peak would be.

Thanks I will check it.

 

[dareed1]

I suspect that there may be some confusion about your system size. Your original order was for 36 340W panels = 11.16kW, and in this thread you posted a picture of your installation. There are 28 panels visible (28 * 395W = 11.06kW). You've stated that you were promised 32 panels, but frankly that seems unlikely, partly because Tesla would have no reason to provide more capacity than you're paying for, and partly because it is doubtful that they would fit. So I'm guessing that your system is really 11.06kW and that's a DC/AC ratio of 1.46. I'll also point out that in the linked thread, I reported that PVWatts suggested a few percent loss of annual generation for your claimed 12.6kW system. If the actual system size is 11.06kW, the loss in annual generation would be even less.

If in fact there are 4 more panels on the other side of the roof, then the PVWatts calculation needs to take that into account, because those other 4 panels will reach peak power output at a different time of the day.

Finally, right now is when the solar insolation is highest, because the air is cleaner in March-April (usually) than the rest of the year, and also the temperature of the panels is lower. Of course, you'll generate more energy in June-July than now because the days are longer but the highest peak power (which is what matters to clipping) occurs about now.

 

[giran99]

I suspect that there may be some confusion about your system size. Your original order was for 36 340W panels = 11.16kW, and in this thread you posted a picture of your installation. There are 28 panels visible (28 * 395W = 11.06kW). You've stated that you were promised 32 panels, but frankly that seems unlikely, partly because Tesla would have no reason to provide more capacity than you're paying for, and partly because it is doubtful that they would fit. So I'm guessing that your system is really 11.06kW and that's a DC/AC ratio of 1.46. I'll also point out that in the linked thread, I reported that PVWatts suggested a few percent loss of annual generation for your claimed 12.6kW system. If the actual system size is 11.06kW, the loss in annual generation would be even less.

If in fact there are 4 more panels on the other side of the roof, then the PVWatts calculation needs to take that into account, because those other 4 panels will reach peak power output at a different time of the day.

Finally, right now is when the solar insolation is highest, because the air is cleaner in March-April (usually) than the rest of the year, and also the temperature of the panels is lower. Of course, you'll generate more energy in June-July than now because the days are longer but the highest peak power (which is what matters to clipping) occurs about now.

Really good info . i will watch the system for few months and see what my energy production is . Thanks very much for detailed info

 

[charlesj]

I suspect that there may be some confusion about your system size. Your original order was for 36 340W panels = 11.16kW, ...

If that Tesla sheet is accurate and as you posted, that does in fact multiply out to 12. 24 kW, not quite 12.6 what he posted.

 

[DrSmile]

Part of the reason that your yearly generation won't be affected that much is because on cloudy days you'll make much more than with less panels.

 

[nwdiver]

Really good info . i will watch the system for few months and see what my energy production is . Thanks very much for detailed info

+1 @dareed1 Here's a Spring vs Summer output comparison. Solar panel output drops ~0.5% / C.

 

[dareed1]

If that Tesla sheet is accurate and as you posted, that does in fact multiply out to 12. 24 kW, not quite 12.6 what he posted.

Yep, I must have fat-fingered the calculator. However, we haven't heard from giran99 if he really has 28 or 32 panels. If it is 28 395W panels, the system power is 11.06kW. Or perhaps these panels are actually higher power than 395W.

 

[giran99]

Yep, I must have fat-fingered the calculator. However, we haven't heard from giran99 if he really has 28 or 32 panels. If it is 28 395W panels, the system power is 11.06kW. Or perhaps these panels are actually higher power than 395W.

i do have 28 in front and 4 in back total is 32