slightly different solar qx
Am looking at solar on a small class A. I currently have 3 group 27 batteries (rv/marine) for the house. (prior owners had just installed 2 new, and I had one from a trolling motor setup) they will...
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The 325 will need an MPPT controller to do "24-12"
max amps to the RV 12v system (loads first , battery gets what is left over) with each aimed at high sun at noon
100w with PWM gets Isc--mine get 6.3 amps
The 325w loses 10% from heat loss (note they give the operating temp)
So 325 - 32 = 293w. Now with good wiring to controller, say a 2% loss so now at 287w input to the controller. Controller loss doing 24-12, maybe 5%, so lose another 14w = 273 output watts.
Amps out is output watts/ battery voltage so take three voltages:
273/12.5 = 22 amps
273/13.5 = 20 amps
273/14.0 = 19.5 amps
So pick 22 amps and that is 22/6.3 = 3.5 tines the amps of the 100,
What controller for the one 325? A Tracer 20 amper would do, but IMO go for a 30 amper for margin.
If you put two of those 325s in series, you could get 44 amps or so--pick a 60 amper? A 40 amper would do with a little over-panelling, which is allowed.
Each 325 has 40 Voc, so two in series would be 80, so the Tracer would work with its 100v limit.
44 amps on 3x 80AH =240AHis an 18% charging rate--no sweat--you can go to25-30% if you want.
max amps to the RV 12v system (loads first , battery gets what is left over) with each aimed at high sun at noon
100w with PWM gets Isc--mine get 6.3 amps
The 325w loses 10% from heat loss (note they give the operating temp)
So 325 - 32 = 293w. Now with good wiring to controller, say a 2% loss so now at 287w input to the controller. Controller loss doing 24-12, maybe 5%, so lose another 14w = 273 output watts.
Amps out is output watts/ battery voltage so take three voltages:
273/12.5 = 22 amps
273/13.5 = 20 amps
273/14.0 = 19.5 amps
So pick 22 amps and that is 22/6.3 = 3.5 tines the amps of the 100,
What controller for the one 325? A Tracer 20 amper would do, but IMO go for a 30 amper for margin.
If you put two of those 325s in series, you could get 44 amps or so--pick a 60 amper? A 40 amper would do with a little over-panelling, which is allowed.
Each 325 has 40 Voc, so two in series would be 80, so the Tracer would work with its 100v limit.
44 amps on 3x 80AH =240AHis an 18% charging rate--no sweat--you can go to25-30% if you want.
