Classic 200 High Power History

[SolarMusher]

Hi guys,
Was watching my Classic history these days, and the high PV input seems to be higher than real output possibilites. Yesterday was very hot and my 2.2kw roof mounted array was hardly ouput more than 1.5kw at 90°F. This morning, datas were 1956Watts high output for yesterday and it was impossible (48PV/48Batt with flush mount Solarworld 175W is not the best way to reach a max output in hot summer days, gonna change later for 72VDC input...). It was the same for the last week.
Was also trying this morning to calibrate the VoltPV and found a -1V difference on the Classic, has someone ever seen such a difference? Is there a better time during the day to calibrate this VoltPV?
Thanks for your help
A+
Erik

[boB]

Hi Erik...

The Classic input voltage being +- 1.0 volt off is OK actually.  Of course I would rather it
not be off at all, but 1.0 volts is within spec at the moment.  This may change in the future.

So, if you want to find the best spot to adjust this voltage, measure the error at Voc.
You can go to the MODE screen and temporarily turn the Classic mode to OFF and
measure the input voltage with your meter and note what the Classic says it is.
Be sure to do this with the TWEAKS input voltage offset set to 0.0

Then, turn the Classic mode to ON and let it sweep down to Max power point and measure
the error again.    Then, adjust the input voltage offset Tweak adjustment to the
best compromise so it is closest at both voltages.   The Max power point voltage will usually
be somewhere between 75% and 82% or so of the Voc voltage when it was OFF.

Next, as far as the high power logging value, it is very possible that you did get 1900+ watts
at one time of the day, especially if there were clouds coming in and out at least once
during that day.  This is because of a prismatic "edge of cloud" event which can temporarily
give you quite a bit more power than the nameplate rating of the PV array.  It usually only lasts for a few
seconds but can last up to around a minute.  It actually focuses more sunlight on your array for a
moment and gives you more than 1000 watts per square meter of power.

Maybe that is what happened ?  It can happen more often than you would think.

boB

[SolarMusher]

Hi boB,
I know cloud effect, I've even seen 2.6kw from my 2.2kw aray (but not in summer).
But for these past days, I was just 30A discharged (830A@48V), so the Classic reach his absorb setpoint (58.4V) very quickly before noon, maybe 11am. And it was 85/90°F... With my old MX (48PV/48Batt), it was a nightmare, thanks Solarwold. May be you're right, I could not spend my time watching my Classic even if I love it but I'm sceptic.
I come back later, need to feed my dogs.
Thanks
Erik

[SolarMusher]

Hi boB,
I'm back, excuse me but they couldn't wait, even for a Classic.
I was telling you that it would take a miracle for my configuration to reach 1.9kw when it's 90°F and absorbing in the morning. But you're right it could hapen just for a few sd at the begining of absorbtion, that's enough. The guy who sold me these panels didn't know about the MX VOC limit (in fact I realised he didn't know anything) and as I told you, it was common to see just 1.2kw output by the MX in full sunshine at 13pm in summer. The Classic seems far better in the same situation (48/48) but I still want to rewire this array for 72VDC as soon as I can, that's the best I can do with what I have. I'm gonna check this high power value in the next days and I'll post you back.
Thanks boB
A+
Erik

[boB]

Thanks, Erik.   Keep an eye on that and report back your findings.  Will be interested to hear/see
what happens.

boB