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lyndon avatar image
lyndon asked

Oversized solar panels for regulator?

Hi folks


I have a Smartsolar 100/20 with a 225w panel connected charging a 12v battery. Looking at the log, it never hits anywhere near full power (110w i think is most I've seen - panel is mounted completely horizontal). I've also read you can add more panels to some controller brands and if they do hit their capacity the excess is just lost, with no damage to controller. Is this the case for my victron smartsolar 100/20? How much could i go over it's rating, would 2x 225w panels be ok?


Thanks in advance for your time!

MPPT Controllers
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3 Answers
Manda avatar image
Manda answered ·

Hi

I connected 600Wc solar panels on a victron 75/15 to charge 12V battery, a few years ago, without major issues. Has just a little bit "melted" the body of the fuse (this controler has a visible one). It is supposed to handle about 200W with 12V system…

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Guy Stewart (Victron Community Manager) avatar image
Guy Stewart (Victron Community Manager) answered ·

Hi @Lyndon,

In most cases, it is fine to significantly oversize the PV array to the current output limit of the regulator. But there are important limitations, specifically around the PV input voltage.

Please watch this Victron MPPT training video where I explain some of these, and of course read an understand the product manual.

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dgnevans avatar image
dgnevans answered ·

You can exceed the wattage of allowed solar but you should never exceed the voltage in your case 100v. I would also not go to high on the wattage as the excess power may be dissipated as heat which could shorten the life of your charge controller if there is not suitable ventilation.

this has been discussed befor on here. https://community.victronenergy.com/questions/7616/what-happens-if-you-add-more-solar-wattage-than-th.html

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JohnC avatar image JohnC ♦ commented ·

The Wattage is irrelevant. Nor will the mppt get any hotter than normal, as the pv power just isn't harvested.

After all, a 100/20 can also handle 24V output, and the newer ones 48V. Still 20 Amps.

Voc and Isc have limits though, and mustn't be exceeded.

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Manda avatar image Manda JohnC ♦ commented ·

in my case (cf. my comment above about a 75/15 controler), I got the fuse (plastic) body a bit melted. Any explanation ? I never went above 75 V, I used a 1st price 20Amps fuse (as I blew the genuine one by inverting the battery polarity)

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Guy Stewart (Victron Community Manager) avatar image Guy Stewart (Victron Community Manager) ♦♦ Manda commented ·

The factory fuse is rated at 25A. There is a chance your 20A fuse is getting very close to it's blow rating, but isn't quite, so it's just getting hot.

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