Should I wire panels in series or parallel?

cralls

Hi All,

I'm having trouble deciding whether to wire my panels in series or parallel. The system is the following:

3 Sunvia OPT330-72-4-100 330W panels
Midnite Solar Classic Lite 200 MPPT Charge Controller
4 Interstate GC2-XHD-UTL 6v 232Ah batteries wired in series/parallel = 12v 464Ah
Magnum Energy MMS1012 1000W Inverter

The Midnite Solar Sizing Tool says I can wire it either way with the 200 controller but I'm interested in hearing which way some of you might wire it and why. Should I wire in series to keep the amps down or in parallel to keep the voltage down? This controller doesn't have arc fault so I suppose that's something to consider if that even makes a difference with this setup.

littleharbor2

 IMHO You would be better off going in parallel with this setup as your 24 volt nominal (72 cell) modules are already double your battery bank nominal voltage. I have the classic 200 as well and with my array of 9 72 cell modules in 3s x 3p my controller runs pretty warm, causing a lot of fan activity in warmer months. My system is a 24 volt setup  I am contemplating adding one more module and running in a 2s x 5p configuration. Your system @12 volts would really pushing your CC MPPT circuitry to it's limits with 3 72 cell modules in series into 12 volts..

cralls

Thanks littleharbor2 for that reply. I was kind of leaning toward parallel anyway. Good to know that I can add that many panels to this charger  

Vic

Hi cralls,

Agree that parallel is probably the best string configuration,  as 3 in series would have a string Vmp of about 108 V @ STC.  This is almost a 10:1 conversion ratio on a 12 V system.

If the PVs are a considerable distance from the CC and batteries is probably the only reason to run three PVs in series.

If you do not already own the Classic 200,  perhaps a Classic 150 would be a better choice if the PV-to-Power room distance is not great (IMO).

With three PVs in parallel,   each of them should have a circuit breaker or fuse,  sized at the "Maximum Fuse Size" as stated on the sticker on the back of the modules,  (or in the PV Data Sheet from the manufacturer).  These breakers are usually mounted in  a Combiner Box,  at the array,  or near the power room,  if the distance from the PVs is short.

FWIW,   Vic