I recently bought some used solar panels that are about 25 years old, because I got a great deal on them. They have some odd operating values, which is confusing me as to which solar charger will work with my system.
I have 6 panels @ 230 watts each (1380w total).
Their specs are ( as far as I can tell. I needed to peice a label together because there is really no information available on them online):
Name: Mobil RA-220 8b
Peak power: 230w
Vmax: 8.27 (V)
PF Pmax: 27.77 (I)
Voc: 10.55 (V)
Isc: 30.49 (I)
I am attempting to make a 24 volt system with either 4 or 6 panels. My friend said some of those values above are labeled incorrectly (volts vs amps). However, with her math, she recommended the Victron MPPT blue solar 100/50 solar charger, which is rated at:
max 1400w
12/24v
Max PV open circuit voltage: 100v
Max battery current: 50 amps
Would this charger work with this setup? If not, why? And is there another comparably priced ($300) charger that would work in the market?
I know I need to connect my panels in both series and parallel. What specifically would you recommend?
Thank you!
Best Answer
Wire the panels all in series to get the highest possible voltage to the controller. This will keep your current lower, requiring less wire, and allow the MPPT charger to work more efficiently. If you are charging a 24V battery bank, you need at LEAST 26V but it will operate much better with higher voltages. Just try not to exceed 100V. 6 panels is probably the max you'd want to run.
The Mobil ra220 panels actually have 2 modules each, and if you're measuring ~9V per panel they are configured in parallel. I'd recommend rewiring them in series for the reasons stated above.