question

joeccv avatar image

MPPT 100/50 vs 150/45 - 1320 watts solar 24v system

Configuration

Looking at the MPPT spec sheets, I would believe the 100/50 would be plenty for the configured panels in this system, although the calculator returns the 150/45. I have the minimum temp configured to -10C, however my real world expectation is more like 0C.

Changing the string configuration from 2s2p to 2s1p returns the 100/20 controller. In this configuration the voltage stays the same yet a 100/series controller is acceptable. Even with this configuration, I would expect to see the 100/30 returned, as the nominal PV voltage is higher than the 580w rating in the datasheet of the 100/20, although I could understand if the calculator is allowing for 30% pv array oversizing.

It would seem to me that the 100/50 is actually my best option when considering price/output, as this array will not be possible to expand in the future. It also appears by the tools graphs that I will max out the output at 45 amps, so the 100/50 will actually allow some more current to get to the batteries.

What am I missing that makes the 150/45 a better option when configuring this 1320w setup 2s2p?

MPPT Controllerssolar sizing
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1 Answer
JohnC avatar image
JohnC answered ·

Hi @JoeCCV

You haven't missed anything. The calculator doesn't consider the price, and just picks the smallest suitable unit based on Amps.

The 100/50 is a good choice for you if it comes in cheaper and is available at your location.

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