So who's turning out peak numbers right about now?
The actual Solstice was a bust, with morning clouds, but June 19 turned in a record 30.8 kWh, with output from 6AM to 8PM:



Not bad for a "3.8kW" system in San Diego.

My three systems did about 59kw yesterday .. about 12kw DC STC

I have heat, partly cloudy weather, arrays on a roof ( 22deg ) when the sun is at 4 deg ... still nice watching the meter spin backwards even with the AC and pool pump running


I assume your "3.8kw" is the inverter not the DC STC of the array?

I see longer "on times" but it's hotter weather, and I've had some equally peak days in May.
about 6, 28KWH days so far this year.

Clouds here also, didnt do that much. 42 or 44k


Fred

This is a good place for me to ask my question. I'm only a little producer compared to you guys but I have been hitting 8 Kwh this month. Anyway, I have 1224 watts of panels and yet my inverter says my peak output yesterday was 1328. I've read about the sun bouncing off clouds and all that but si it really possible to go that much above the rated 100% output?

it is very possible, as the pvs are rated at 1000w/m^2 and during the summer solstice that could easily hit 1100w, 1200w, etc. depending on your location in addition to how well the pvs are aimed and maintained(cleaned). simply put, the solar intensity is highest at this time and could easily go above the standard they measure them at. also, keep in mind pv tolerances can sometimes go above their rated power as it is usually a + and -%. this means if your pvs average say 3% above their rating this also adds 30+watts in your case at the 1000w/m^2 rating so it's even more at higher solar intensities.

The 3 Fronius units I tested reported all reported 5% high on ac watts. I reported this to Fronius and they claimed it was just a one off thing.

In a very broad generalization, every inverter manufacure except Xantrex reported high, PVpower and Fronius were +5% , SMA was +2-3%. While not gridtie, the Outback MX60 was +20 to+30%. In general the feedback I get is the manufactures NEVER hear complaints when the units report "better than expected" performance numbers, It always rubbed me the wrong way, but I'm not most people

Neil makes vaild points as well, though, I have never recorded more that 930 wmsq here in Florida in clear conditions and I thought only elevated places ( say 5k feet ) got over 1000 wmsq. With edge of cloud, I get near nameplate DC, but I have Florida heat, lower than 1000 wmsq and off angle to deal with. Now in cool/cold conditions one can easily be higher than nameplate

It's actually a GT4.0 inverter, but the system was originally designed (and rebated) as a 3.8, with a last-minute inverter upgrade, so it's like a bonus to me.

The graph is showing AC Watts.

The DC STC is 4.5kW (22 x 208W panels), but there is some chimney shading on the west-facing string.

What's the best way to measure wmsq? Can I just take the DC power, the area of my panels, and my pocket calculator, or is it more of a pure irradiance measurement?

My measurements were with calabrated irradiance pyrometer.

You can get a pretty good idea using the GT's DC volts and DC Watts ...

Take the DC volts, compare to the name plate vmp point of the solar panel and the difference is due to tempature ( usally a fractional percentatge when hot )

Then, take the DC power / ( Nameplate * the above fraction ) and that would be close to the wmsq.

In a perfect 25C panel tempature the DC power would be = nameplate at 1000wmsq irradiance.