question

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MPPT sizing - over or under?

Using the online tool and specifying my panel params, it suggests the 150/70 mppt. However, when I use the excel calculator, the 150/100 seems to be "green" for all items. My question is: is it better to over or under size the controller? I would assume oversize allows for maximum power output in all conditions.


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MPPT - Solar Charge Controller
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1 Answer
rainer avatar image
rainer answered ·

MPPT 150/70 and MPPT 150/100 have the same self consumption and efficiency. Therefore, there seems to be no drawback when over-dimensioning, except for the higher price.

When under-dimensioning the MPPT, the power for charging the battery is limited with the highest output current that can be generated. Therefore, in some scenarios some power that could be generated by the solar panels is wasted.

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