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
The highest battery bank SOC we ever get to is late afternoon before we start hitting the 12v to run things again. After that starts, say 5pm, the SOC drops till next morning sometime after breakfast when it gets to the low SOC point for the day.
So the solar time between lowest SOC and highest SOC is fairly short when you can move the SOC up. Any solar earlier and later after supper till after breakfast while it is still daytime just slows down how far down in SOC you get to by next day, which helps by not having as far to go up next day.
The only value of the solar controller till 5pm is near the end, to stop the batteries getting over 15v, the inverter high voltage shut off, so you can run the MW to make supper and also watch TV. Holding the battery voltage at 14.9 or below is good.
But you want to get to 14.9 so you get to the highest SOC possible by keeping the battery amps acceptance rate as high as you can so amps don't taper on you from that.
With PWM, you can't stop amps from tapering a little before you get to Vabs due to the IV curve, but you can play with the high set point to have Vabs at 14.9.
With MPPT it all gets weird at that stage, so I will have to find out how to play that for best results.
So the solar time between lowest SOC and highest SOC is fairly short when you can move the SOC up. Any solar earlier and later after supper till after breakfast while it is still daytime just slows down how far down in SOC you get to by next day, which helps by not having as far to go up next day.
The only value of the solar controller till 5pm is near the end, to stop the batteries getting over 15v, the inverter high voltage shut off, so you can run the MW to make supper and also watch TV. Holding the battery voltage at 14.9 or below is good.
But you want to get to 14.9 so you get to the highest SOC possible by keeping the battery amps acceptance rate as high as you can so amps don't taper on you from that.
With PWM, you can't stop amps from tapering a little before you get to Vabs due to the IV curve, but you can play with the high set point to have Vabs at 14.9.
With MPPT it all gets weird at that stage, so I will have to find out how to play that for best results.
