150/70 Victron or slight overpanel a 150/60 ?

charly

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3 x 315w panels with 40V VOC and 10 amp ISC. Going in a 12V system.
Planning on putting them in series. So 120V VOC total, and the temp coefficient has them still good for a 150V rated SCC.
The 150/60 has the nominal 12V wattage at 860, so it would be overpaneled by 85 watts or ~10%.
 

Dzl

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Either would be fine, what is the price difference?
 

chrisski

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For $50, I would want to get the 150/70.

Part of the reasoning behind that is I'd expect the 3 panels not to put out the chargers maximum 70 amp wattage, and depending on how much it fell short, I might have the option to add a fourth panel down the road and install that 2S2P. The 70 amp model I'd also think about keeping that down the road if I upgrade or move the system to a new place.

I've found my flat panels are underperforming my expectations, but my portable panels I tilt and move with the sun three times a day are exceeding my expectations. For portable panels, I get about 5.3 amps out of my 6 rated amps, but my flat panels only can make 3 of 6 rated amps. So if the panels are flat, I'd expect it to fall short. If the panels are titled, they may produce close to the 70 amps for some portions of the day. I get about 5.3 amps out of my 6 rated amps.
 

Dzl

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Which works out to like ~10% or so, I'd go with the larger one I think, as Chrisski mentioned, room to expand in the future if you choose to, and no compromises with the current setup (even if you would rarely exceed 60A in practice)
 

charly

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Thanks. Cant add a fourth panel on the roof as the 3 literally take up near all of it.
Would be adding a separate SCC for remote panels.
 

Dzl

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Thanks. Cant add a fourth panel on the roof as the 3 literally take up near all of it.
Would be adding a separate SCC for remote panels.
Then its really a personal decision, cost/benefit wise the cheaper controller probably makes more sense. But if you want to harvest every last watt-hour and run a little cooler maybe(?) you could spend the extra $50.
 
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