De-rating the 230w
I hauled the 230w Schottpoly out to see if I could tone down the voltage by turning it or partially shading it. I found that to get the Voc down to 32v by turning it, I had to turn it 90 degrees to...
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Thanks for that test. I am surprised it took that big of a cell covering to get the Voc down, but at least the idea works.
My 230w Hanwha panel has an Isc of 8.3a which it does in full sun if not 8.4 Voc rides around 34v of its 36.8Voc as soon as the sun gets on it, it warms up fast, which drops the Voc. I see solarblvd has a Hanwha 235 going for $160! Mine cost me $260 last year up here :(
I still don't know if the Isc of a 24v panel like that has any meaning at all for what amps you get with the buck MPPT controller.
I am suspecting the Isc has nothing to do with it, and it is all about the wattage at the controller output divided by the battery voltage.
OTOH, the 12v panel gets Isc in full sun and you can use Isc as your "expected amps" with the usual PWM controller.
My 230w Hanwha panel has an Isc of 8.3a which it does in full sun if not 8.4 Voc rides around 34v of its 36.8Voc as soon as the sun gets on it, it warms up fast, which drops the Voc. I see solarblvd has a Hanwha 235 going for $160! Mine cost me $260 last year up here :(
I still don't know if the Isc of a 24v panel like that has any meaning at all for what amps you get with the buck MPPT controller.
I am suspecting the Isc has nothing to do with it, and it is all about the wattage at the controller output divided by the battery voltage.
OTOH, the 12v panel gets Isc in full sun and you can use Isc as your "expected amps" with the usual PWM controller.
