Question about SolarEdge inverter sizing and clipping

[jdonalds]

New here. Our system powered up officially on Jan 16.
- 18 panels, LG365Q1C-A5
- 18 SolarEdge P400 Optimizers
- SolarEdge SE500H-V5 Wave
- DC Rating 6.57 KW DC

The system is rated 6.57 KW but it is clipping at 5000 watts. Even in the winter with the sun low it is clipping for long periods. We live in Redding, CA, the 2nd sunniest city in the U.S. after Yuma AZ. When summer comes we have blue skies with zero clouds for months at a time. When the sun is in summer position our system will be clipping for hours.

I don't understand the logic behind the decision to put a 5,000 watt inverter on a 6.57 Kw system. Can anyone shed some light on this? I have a call into the installer to see what they say about this situation.

I would post a graph of the clipping but I don't see a way to add a photo here.

Thanks,
John

[sensij]

Inverter reporting. I have the SE 7600A inverter.

I have one of those, and an SE3000A on a different system. I'm skeptical that the inverter is really producing more than 7600 W, because even though the data sheet indicates that a 3000 W inverter has peak output of 3300 W, and the inverter itself has occasionally reported output a couple percent over the 3kW rating, those values were never confirmed by the revenue grade meter I put in to independently monitor the output. For example, the peak power the RGM measured on 3/22/16 was 2940 W, against the 3072 W reported by the inverter for that period. (The RGM CT's were located right at the inverter, so AC loss doesn't explain the difference).

When you see the DC voltage spike up from its baseline, that indicates that clipping is occurring. If the power output associated with the clipping events is not a stable number, it casts doubt on the consistency of the measurement and data processing the inverter performs to determine its "power generated" metric. Even if the power output it is reporting were accurate, the DC voltage charts are suggesting that something around 7900 W is the clipping limit of your inverter, not the 8350 W that the OP is getting from the inverter's data sheet.

The inverters only need to have accuracy of 5% to meet CA standards, and SolarEdge, in particular, seems to consciously use that range.

[macaddict]

Is that based on what the inverter is telling you, or a revenue grade meter?

Inverter reporting. I have the SE 7600A inverter.

[sensij]

I'm not sure about this. I have the SE 7600 inverter and the other day it showed 7849 W at 10:20 AM:

https://pvoutput.org/intraday.jsp?id...59&dt=20171031

Is that based on what the inverter is telling you, or a revenue grade meter?

[macaddict]

Both Solaredge 7600 W inverters clip at 7600 W. An 8.4 kW array will probably clip a little bit in spring, but the value of the energy lost will be insignificant.

I'm not sure about this. I have the SE 7600 inverter and the other day it showed 7849 W at 10:20 AM:

https://pvoutput.org/intraday.jsp?id=59404&sid=52859&dt=20171031

[inspron]

So if I have an array of 8450DC in San Diego I won't get full annual output with the HDWave, correct?

Thanks.

Your installer chose the right size inverter for the job. You have a 1.1 DC oversize ratio. Which is the same oversize ratio as mine, also in San Diego with the HDWave. Over a year, optimistically, you may lose 10-50kwh worth of production or about $10 worth of electricity due to clipping - although that is doubtful. Personally, if I had to do it all over again, I wouldn't mind going 1.25 ratio in San Diego.

[sensij]

Am I correct that these inverters clip when they reach max AC output? So if I have an array of 8450DC in San Diego I won't get full annual output with the HDWave, correct?

Thanks.

Both Solaredge 7600 W inverters clip at 7600 W. An 8.4 kW array will probably clip a little bit in spring, but the value of the energy lost will be insignificant.

[so_cal_burbs]

The SolarEdge inverter line advertises that the traditional inverter allows DC oversizing of 135% and the HD Wave 155%. I believe but am not certain that this is a warranty thing and that the inverter would clip at rated watts. Their data sheet shows Max AC output at 8350 for the SE7600A and 7600 Max AC output for the SE7600H-US.

Am I correct that these inverters clip when they reach max AC output? So if I have an array of 8450DC in San Diego I won't get full annual output with the HDWave, correct?

Thanks.