Will this work?

DenverGuy

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I bought an Epever 30A MPPT controller for a four 100W panels. I considered the input amperage but not the input wattage. The max input is 390W. I know the that the panels aren't 100% efficient. Will this work, or am I too close to the limit?
 

sunshine_eggo

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Will work fine.

It's not at all uncommon to "over-panel" a controller, i.e., put more wattage on it than it can deliver.

As long as your don't exceed the PV input voltage limits or the PV input current limits, you're good.
 
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DenverGuy

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Thanks, that's reasuring. How much wattage could a 100W panel actually produce?
I bet it's a lot less than 100 watts.
 

sunshine_eggo

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Thanks, that's reasuring. How much wattage could a 100W panel actually produce?
I bet it's a lot less than 100 watts.

It depends completely on circumstances. A number thrown around is 80% of rated.

Ratings are based on conditions that don't usually happen in the real world, but sometimes a combination of circumstances can even allow GREATER than rated output. My 3kW array briefly put out 3.6kW (+20%) due to extreme cold. Cells were below freezing, and the panels are at 6500' elevation, so the atmosphere is about 15% thinner. Combine those two factors, and I was able to get 3600W in December - 5 days from the worst solar conditions of the year with the panels tilted for "year round" performance. But that's not typical.

Most panels have a NOCT rating, which is a more realistic performance number.
 
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