SE7600H clipping at 7.9KW

[wwhitney]

Shouldn't Tesla have given me an inverter big enough to not clip?

No, that would have been a waste of money.

Both inverters and panels cost money. For a system where PV DC size = inverter AC size, adding another a PV panel lowers the system average $/kWh generated, even though it may cause some clipping. Because the extra power that additional PV panel generates didn't incur any additional inverter cost. This continues to be true up to DC/AC ratios well over 1.0.

Maybe the extra heat in the summer will lower the panel efficiency enough that I don't see as much difference in middle of the day peak in winter vs summer.

Indeed, clipping is more likely in cold weather, the temperature effect can be larger than the incidence angle effect (depending on your roof slope).

Cheers, Wayne

 

[Ampster]

Any reason this strategy is bad?

No, assuming you have the roof space for more panels. It used to be argued that inverters were less efficient at lower perentage of capacity but I don't think that applies to today's inverters. It will complicate your busbar calculations but things are already complicated enough. Presumably PG&E will have to redo your PTO because you are changing to more inverters. That should not add much to the already complicated system design. I would think the delays that that would cause would only be hypothetical. However I agree with Wayne that it is a waste of money but in your case you are getting 100% grant money so it is not your money.

 

[h2ofun]

No, that would have been a waste of money.

Both inverters and panels cost money. For a system where PV DC size = inverter AC size, adding another a PV panel lowers the system average $/kWh generated, even though it may cause some clipping. Because the extra power that PV panel generates didn't incur any additional inverter cost.


Indeed, clipping is more likely in cold weather, the temperature effect can be larger than incidence angle effect (depending on your roof slope).

Cheers, Wayne

Other than a larger inverter is a waste of money, any other negatives?

 

[Vines]

Other than a larger inverter is a waste of money, any other negatives?

The busbar calculations will be more difficult when you oversize inverters. Interconnection permission is also based on maximum inverter size. You will see more transformer upgrades required when oversizing inverters. Often the AHJ will have some number like 10-20 kW system size where they don't look quite as deeply into the plan check process. If you exceed it for no reason you are just making more work for yourself.

 

[h2ofun]

The busbar calculations will be more difficult when you oversize inverters. Interconnection permission is also based on maximum inverter size. You will see more transformer upgrades required when oversizing inverters. Often the AHJ will have some number like 10-20 kW system size where they don't look quite as deeply into the plan check process. If you exceed it for no reason you are just making more work for yourself.

Sure glad I am paying folks who know all that stuff. I just write the checks. What work for myself will I be having If I know nothing about the technical details?

 

[nwdiver]

Oh, and why am I showing 7.9 when given the breaker size it should be 7.6?

Breaker sizes are based on Amps not kW. So you're using a 40A breaker rated to 32A continuous. As @Vines pointed out (247v)(32A) = 7.904kW. Some inverters are power limited (also limited by current) and some are current limited but not power limited. Depending on the actual limit of your inverter you could get even higher power. The high spec for 240vac is 264 so even (32A)(264v) = 8.4kW might be possible.

 

[hayhayday]

My 3800 clips at ~3.95kw voltage also around 247v during the day , powerlimit in setapp says 4kw maybe yours is 8kw?