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Small Cabin Forum / Off-Grid Living / charge controller
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beachman
Member
# Posted: 11 Dec 2018 14:11
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I have a 12 volt system the runs a 100 watt pure sine inverter. I was thinking of getting about 6 - 285 watt panels to run in series to pump the voltage for about a 400 ft run (about 175 volts), then attach to a charge controller to charge say 6 - 6volt batteries in series/parallel to keep the system at 12 volts. This creates a huge amperage and is there a charge controller that will handle this? All suggestions (within reason) welcome.

beachman
Member
# Posted: 11 Dec 2018 14:11
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Should be 1,000 watt inverter - sorry.

ICC
Member
# Posted: 11 Dec 2018 15:45 - Edited by: ICC
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Midnite Solar (classic) (KID), Outback, Schneider all have online "string" calculators you can use to enter battery bank voltage, panel data, etc. and see which of their charge controllers will cover the voltage, amps, watts involved. You can choose different panel connections; so many series, parallel.

There may be other similar tools for other charge controller brands but I am only familiar with the ones I linked to. I've used all three over the past almost 20 years

Note that if you have cold temperatures you should be certain to enter the data for that as voltages rise with the cold and is can be easy to connect too many panels in series and then overvolt the CC on a cold morning, especially when the sun first hits the panels. There can be a surge and the calculators factor that into their calculations. The basic NEC calc is to take the Voc of the panels and multiply by 1.56 for the possible highest voltage spike. (in truth you multiply Voc x 1.25 x 1.25, but that is equal to Voc x 1.56)


You should also be aware that the same CC connected to a 12 volt battery bank cannot handle as many watts total of pv panels as a higher voltage bank. Sometimes when re-doing a 12 volt system you are money ahead if you switch to at least a 24 volt system, if not 48 volts.

Play around with one of those calcs; enter your panels and then compare CC suggestions with a 12, 24 and 48 volt battery.

creeky
Member
# Posted: 11 Dec 2018 16:07
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What ICC said.

250v controllers are available from Victron and some chinese suppliers have 300v/100a. There are 600v available from Schneider and Morningstar.

Going to a 12v battery bank is not a great idea. For your 300wX6 for 1800w / 13v = 140 amps.

Victron has a 250v/100a. Its something over $1200.

1800/50 = 36 amps. See the advantage of higher voltage. You just went for 2/0 cables to 6 gauge.

The Victron 250/60 would work. I think its around 800 usd. Haven't priced one lately. Sold a couple in the spring. Super easy to program. Love 'em.

beachman
Member
# Posted: 11 Dec 2018 19:15
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I kind of thought the 12v would be too light. Maybe time for a system upgrade - or leave well enough alone for now. Next go around will be a higher voltage system. Thanks!

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