My system is clipping on 12.6kw system with 7.6 inverter

[charlesj]

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

What is the orientation of the rears and the front.

 

[adspguy]

I’m in the Boston area too. I have a 36 panel, 12.24dc/10kwAc system. Tesla put in a solaredge inverter for my system. Here is a plot from a recent sunny day. There is some clipping this time of year for an hour or two, even with the 10kW inverter Tesla estimated I’d get 11.2MWh/year and last year I got 11.75. All of my panels get sun all day.

 

[adspguy]

Here is what my last week looked like.

 

[solarAddict]

I'm in Boston area as well and my array is 30 panels 10 kW with 7600 inverter. I have some clipping but only in some fully sunny summer days as my array is in fact consists of few groups of panels facing east and south. Here is data from the same day as the one posted by adspguy .

 

[charlesj]

I’m in the Boston area too. I have a 36 panel, 12.24dc/10kwAc system. Tesla put in a solaredge inverter for my system. Here is a plot from a recent sunny day. There is some clipping this time of year for an hour or two, even with the 10kW inverter Tesla estimated I’d get 11.2MWh/year and last year I got 11.75. All of my panels get sun all day.
...

Yep, that is a 1.22 DC to AC ratio. Just think what it would look like or how much more production with more panels, same inverter.

 

[unitDissipator]

I'll resurrect this thread a bit, as just yesterday I had 32 400W panels (12.8 kW) installed with the 7.6 kW inverter south of Boston (one powerwall+ and one powerwall). Half the panels face SW, the other half SE. I'm also concerned there could be more clipping than I'd like. I've also been told that the tesla inverter can handle higher loads (but no one specifies for how long, I'm guessing it's very short term). I guess well see if adding a 3.8 kW inverter will be worth it. I did run PVWatt on the two different panel directions, and this is what is looks on a sunny day in Aug. Like other(s) have said, when I look at total power reduction over the year it's only 2.5%, which, if true, I'd be fine with. Well see.

 

[offandonagain]

I'll resurrect this thread a bit, as just yesterday I had 32 400W panels (12.8 kW) installed with the 7.6 kW inverter south of Boston (one powerwall+ and one powerwall). Half the panels face SW, the other half SE. I'm also concerned there could be more clipping than I'd like.

I have the same size system: 12.8kW solar, single 7.6kW inverter. My situation is a bit different--north-facing roof with low slope, some shading in the morning and evening, I'm in N California--but based on what I'm seeing:

• The inverter will max out at ~7.7kW. I've never seen it go above that, not even temporarily.
• Yes there's lots of clipping this time of year, but I'm happy with the overall output.
• It's the yearly output that matters and that's a negligible difference based on PVWatts (2% reduction in my case).

Here's a sunny day in June:

 

[charlesj]

I'll resurrect this thread a bit, as just yesterday I had 32 400W panels (12.8 kW) installed with the 7.6 kW inverter south of Boston (one powerwall+ and one powerwall). Half the panels face SW, the other half SE. I'm also concerned there could be more clipping than I'd like. I've also been told that the tesla inverter can handle higher loads (but no one specifies for how long, I'm guessing it's very short term). I guess well see if adding a 3.8 kW inverter will be worth it. I did run PVWatt on the two different panel directions, and this is what is looks on a sunny day in Aug. Like other(s) have said, when I look at total power reduction over the year it's only 2.5%, which, if true, I'd be fine with. Well see.
...

So, if I understand, you have one 7.6 kW inverter for both strings.
If so, not sure adding that 3.8k inverter will help as either one of those strings will be over that and clip while the other will not.
May want to run 2 more tests on that PVWatts, one string on that 7.6 inverter, the other on the 3.8k and see what the annual production would be on the 3 conditions, all on existing vs the two different inverters. Not sure you could add more panels to the string on that 7.6k that would reduce what is clipped on the 3.8 inverter. Then, of course the economics of all this.

 

[CrazyRabbit]

your agreement, second attachment, says you are to have two inverters, 7.6 & 3.8 kw. do you not.

 

[Mase408]

I have a 16.8kw system with 2 inverters & 1 PW in Nor Cal. Since my PTO in the past 2 weeks I have been capped at 12kw. It has been high 90’s with no cloud or shade. Tesla told me my system is working fine. Even with clipping, I would expect to produce 15kw?

 

[solarAddict]

I have a 16.8kw system with 2 inverters & 1 PW in Nor Cal. Since my PTO in the past 2 weeks I have been capped at 12kw. It has been high 90’s with no cloud or shade. Tesla told me my system is working fine. Even with clipping, I would expect to produce 15kw?

What inverters do you have?

 

[Mase408]

What inverters do you have?

Two 7.6 inverters. Recent install and PTO within the last 2 months

 

[BGbreeder]

I have a 16.8kw system with 2 inverters & 1 PW in Nor Cal. Since my PTO in the past 2 weeks I have been capped at 12kw. It has been high 90’s with no cloud or shade. Tesla told me my system is working fine. Even with clipping, I would expect to produce 15kw?

Why do you expect 15kW?

Have you run PVWatts for your exact set up? If not, that is the first step.

Generally, given your location, and the typical roof angles in northern California, I would be surprised.

All the best,

BG

 

[dareed1]

To expand on BGbreeder's comments, the actual power produced by solar panels depends on the exact azimuth (where due north is 0 degrees) and roof angles. Either enter that info into PVWatts or post it here to get an estimate of expected power. Also note that high solar panel temperatures degrade solar production by roughly 0.5% for each degree C above 25C. Your panels are probably running at 50C, maybe more in high 90s weather.
I'm in Belmont (perhaps 8C cooler than Danville), and based on our production, I wouldn't expect you to get more than 13kW at the peak. But that's just a rough idea; the azimuth and roof angles are key.

 

[charlesj]

... Also note that high solar panel temperatures degrade solar production by roughly 0.5% for each degree C above 25C. Your panels are probably running at 50C, maybe more in high 90s weather.
...

Just on this part with me able to check Enphase panel/inverter temperature, I have seen 50C+ with less air temps and no skirting to reduce air circulation.
Yes, temperature eats away production.

 

[Mase408]

Why do you expect 15kW?

Have you run PVWatts for your exact set up? If not, that is the first step.

Generally, given your location, and the typical roof angles in northern California, I would be surprised.

All the best,

BG

Thanks for the feedback.
I expected 15kw due to two 7.6Kw (15.2kw total) inverters. But I guess I am wrong due to other variables.

I ran the PVWatts with my 16.80kw system. I didn't adjust any of the system info except fixed roof mount. I received 26,610, annual production which is much higher than I expected.

 

[BGbreeder]

Roof slope and orientation are the driving factors in your production.