Solar Panel Voc-MPPT?
Wondering if there is any relationship between measured Voc and MPPT performance with a 24v panel. My 12v panel has a Voc rating of 21.9 and Isc of 8.2, but I often see 8.2ish when Voc is only 20....
Forum Discussion
BFL13 wrote:
You need the same lighting to last through the time it takes to swap controllers, as you know, so such tests require special days where there are no pretty white clouds rushing by all the time screwing up the readings.
What time of day was the 10a?
My flat vs tilted and tracking results in May at 49.2N were 56, 70, and 90 AH/day but % diffs in amps at any one time of day varied by time of day. (single 130w panel)
Time, Flat , Tilted, Tracking- Amps
0700- 1.0, 0.6, 3.7
0800- 2.0, 1.7, 5.7
0900- 3.6, 3.6, 7.3
1000- 5.1, 6.2, 8.1
1100- 6.3, 6.8, 8.2
1200- 6.9, 7.7, 7.7
1300- 7.2, 8.3, 8.3
1400- 7.1, 7.7, 7.7
1500- 6.4, 6.9, 8.1
1600- 5.0, 6.6, 8.1
1700- 3.9, 5.4, 7.3
1800- 2.0, 3.3, 5.7
1900- 1.0, 1.7, 3.7
tests started at 1pm PDT yesterday, so about Noon PST. yesterday and it looks like today are completly clear skies, yesterday didn't even have any jet contrails to worry about. Just hope it holds today.
Look to do the PWM vs. MPPT today about 1pm PDT.
the "flat" vs. "optimum angle" test occured at about 3pm PDT. so given the time of year and latitude, sun was getting low on the horizon.
And yes, even wispy clouds can make a noticeable difference in output power. Really do need clear skies to make decent comparisons.
