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I have Victron Bmv 712 monitor & Victron Mppt 100/30 smart controller. Battery bank is 2 x 110 amp connected in parallel = 220 amps @ 12 volts. I'm installing 2 x 140 watt solar panels. Would it be best to connect them in series 12volt or parallel 24 volt ?
Series wire your panels Harvey. Just look at the Voc rating on the sticker on the rear of your panels. Added together should be well less than 100V. If not, come back, yeh really, come back..
Poor light performance. It's all fine to read pv panel spec sheets, but those are specced for optimum conditions, and what they don't tell you is that V of all kinds drops away when suboptimal conditions happen.
Like before the sun gets over the horizon in the morning. There's light, but often not enough V generated to kick away a cc. 2x seriesed panels give that V a 'double chance' and will kick off earlier, then hang in longer at sundown and with really bad cloud.
To get the most from an mppt cc, give it some V to work with. But NEVER exceed that 100/ spec on it, that's adding Voc on your pv string. Then leave a margin too..
It depends on your panel's specs. if it's '12 panels' definitively wire them in series to make the MPPT work well.
if it's 35-40 volt panels, wiring in series gives less transport losses (1/2 of the current vs parallel).
(partial shading might have influence on best setup, but a bit complicated to explain)
@JohnC Thanks John, so what is the benefit of wiring in series as opposed to parallel?
Harvey
Generally speaking the higher voltage means smaller wires compared to lower voltage (which means higher ampage). That is the general principle in play here. Understandvthere are many more factors at play but we are talking generalities here.
Thanks very much guys, I think it's something to ponder
