question

yswery avatar image
yswery asked

Will this PV set up damage my charge controller?

We have a 100/30 controller and recently had to replace our panels. Since we could not find the exact same panels we ended up getting something that was a touch bigger


New Panel specs (total of 2 panels)

- 290W
- Open Circuit Voltage (Voc) 38.4V
- Short Circuit Current (Isc) 9.59A
- Maximum Power Voltage (Vmp) 31.8V
- Maximum Power Current (Imp) 9.12A


We have a 12v battery bank


1) These panels are going to be mounted in a place where shadows are never an issue, should these be wired in series or parallel along side the 100/30 controller?

2) (more importantly) Will this set up have the potential to damage the charge control being overpowered for the 30A charge rating? or will the controller simply "max out" charging at 30A and any excess solar generation will be simply ignored?

MPPT Controllers
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4 Answers
snoobler avatar image
snoobler answered ·

1) Whichever you prefer.

2) No. Provided you stay under the 100Voc limit and under the PV current input limit of 35A, you are safely over-paneled.


The unit will ignore any available power that would exceed the rated 30A output.

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kevgermany avatar image
kevgermany answered ·

You have a good amount of headroom, but if you go for a series connection, it would be best to check temperature voltage change against your coldest temps.

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snoobler avatar image
snoobler answered ·

76.8Voc would require a 30.2% increase in Voc

-0.33%/°C is a pretty conservative coeff.

2S should be good down to -66°C/-87°F

Very few places on the planet where this might be possible.

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Kevin Windrem avatar image
Kevin Windrem answered ·

The charge controller will limit OUTPUT current to it's maximum (30 amps in your case) even if more solar power is available. So there would not be any damage.

You'd be safe running the panels in parallel but could come close to the 100 volt maximum with the two panels in series, depending on your coldest temperature.

Plug the numbers for your panels into the calculator here for a better idea:

https://www.victronenergy.com/mppt-calculator

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