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billy-myers avatar image
billy-myers asked

Solution for SmartSolar 100/20 with a 2amp overage

Friend was given a SmartSolar 100/20 as a gift to help get more out of his panels but it appears that with the ideal panel configuration the Isc will put him at a total of 20.43a. Will being over .43a force him to not use this config or is there a little tolerance that would allow this to be alright?

Panel Qty Watts Voc Vmp Isc Imp

Trina - 2 300w 39.8v 32.6v 9.77a 9.19a

Othr - 6 100w 17.8v 5.62a

Ideal/Optimal Configurations

1a) Othr 4S = 400w/71.2v/5.62a

1b) Trina 2S = 600w/73.6v/9.19a

Parallel 1a with 1b = 71.2v/14.81a=1,054.47w

Or

1a) Othr 3S2P = 600w/53.4v/11.24a

1b) Trina 2S = 600w/73.6v/9.19a

Parallel 1a with 1b = 53.4v/20.43a = 1,090.9w


MPPT Controllers
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2 Answers
Mike Dorsett avatar image
Mike Dorsett answered ·

The output voltage will determine the current: and hence the max power that the charger can handle:

20A @ 12v = 240W

20A @ 24 V = 480W

20A @ 48V = 960W.

So unless your friend is running a 48V system, the additional panels should not be used. If 48v then:

1a) Othr 4S = 400w/71.2v/5.62a

1b) Trina 2S = 600w/73.6v/9.19a

Parallel 1a with 1b = 71.2v/14.81a=1,054.47w

will work, as the string VOc's are close enough.

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kevgermany avatar image
kevgermany answered ·

?

Batteries will charge at quite a bit more than nominal voltage, e.g. 12V will charge at 14.2V or more depending on battery type/settings. So 20A at 14.2V will give 284W in this example.

If there's more available from the panels, output will be restricted by the MPPT. This is explicit in the MPPT manuals. So excess theoretical panel power is OK and will give better charging in less than ideal conditions. The killer is over voltage going into the controller.


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