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sappleby avatar image
sappleby asked

Am I maxxed out?

This is my first time working solar, adding a system to my motorhome. I’m still installing the hardware (wiring, mounting the controller, etc) I have two 200 watt mono panels that will connect to a SmartSolar 100/30 MPPT. I may have an opportunity to add one, maybe two more, 200 watt panels. If I understand the specs and the math right, I’m already at about the maximum for my charge controller, right? My question is, can I add 200 or 400 more watts in PV without doing damage to something and, will I get any benefit from this?

Pmax. 200w

Voc 27V

Isc 9.66A

Vmp 22.6V

Imp 8.85A


MPPT SmartSolar
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2 Answers
Matthias Lange - DE avatar image
Matthias Lange - DE answered ·

I guess you system voltage is 12V.

The MPPT 100/30 can charge with up to 30A.
30A at 12V is 360W (during the charging the voltage will go up -> more power)
With 400W at the MPPT you will be good.

Adding more will not give you more charging power (in summer).
However in winter and bad weather you will get more power.

I would recommend you to add another 100/30 for the other panels to be able to use all the power in summer (for AC for example).

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sappleby avatar image
sappleby answered ·

Yes, sorry, 12V battery, 420AH. So more panels would be helpful on days less than ideal for solar charging? On those bright, sunny, summer days, will the controller suffer damage or reduced life? Or, does it simply not let the extra power through with any adverse effects? And, what happens to the extra energy, heat produced?

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kevgermany avatar image kevgermany ♦♦ commented ·
Rule of thumb, overpanelling power up to 30% is OK. As long as you don't over volt af any time.
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