Niner said,
"Why would panel V be pulled down to 13V? With PWM, you are interested in Isc in amps, or 8.5 amps per panel. You assume the battery can take that full 17 amps. Sometimes it can, if below 85 to 90% state of charge."
I'm not assuming anything. I know for a fact that my 430Ah bank can accept over 30a at 90% soc, at 14.8Vabs. Moreover, in winter, and do to my work schedule and where I sometimes have to park, gen charging from 5-6:30am may not always be an option. So I may very well have to use solar on a fairly heavily depleted bank, from morning 'til evening, when I can then fire up the gennie. And, there will be loads running, all the while.
As per the pwm pulling panel voltage down to 13v, this would indeed happen if my bank got down to 12v. So, 13v and 16a for the pwm. The mppt, however, could produce as much as 20a in such a situation, thus making up for the continual loads (heat pump, fans, fridge, etc.)
To add two more panels, it would cost about $340can. The Tracer 3215BN will cost about $275can., so no savings to be had going with more panels.
