question

karlheinzhaller avatar image

Minimum Input Voltage for the MPPT

Will the MPPT150./100 shut down or does not start if the input voltage is below 49V?

Attached photo of array design for review. 150-100_2 Panels_5 Parallel.png

MPPT Controllersvoltage
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4 Answers
Guy Stewart (Victron Community Manager) avatar image
Guy Stewart (Victron Community Manager) answered ·

Hello Karl,

As mentioned in this Victron MPPT FAQ - The panel voltage needs to be at least 5V above the battery voltage for the charger to start power conversion.

2 x 60 cell panels in a 48V system is usually insufficient, 3 panel strings are usually required for reliable operation.


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JohnC avatar image
JohnC answered ·

Hi Karl. I'm sure Guy won't mind me attempting an answer, and should correct me if needed.. :)

As I understand it, the 5V 'kickoff' point is the difference between the batt Vactual and the panel Voc. Once satisfied, that effectively changes to Vactual vs Vmp, and the 5V becomes 1V minimum under load.

This of course comes into play at least twice a day, sunup & sundown. And depending on your local weather & seasonal conditions may also extend into the general daytime. The calculator is working on 'optimum' conditions, and sure, should okay 2x series of your panels.

But they may be late risers and early retirers. Panel V doesn't always hold to spec in poor conditions, and if you saw that happening through the day, it's not what you want.

Up your sleeve a change to 3s-3p, leaving a spare. :)

Lesser kit just clickety-clacks in the half-dark...



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wkirby avatar image
wkirby answered ·

If you use a MPPT 250/100 then you can configure your array for 5 series and 2 parallel and that would probably be below the maximum voltage for that controller.

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karlheinzhaller avatar image
karlheinzhaller answered ·

Hi Guy, thank you very much for your reply. Using the MPPT calculator whit this configuration, 2x305W 60 cell panels and the 150/35 results as an accepted solution. I'm not able to attached the Excel spread sheet. Any reason why?

To what starting voltage is the calc referring to? Is it 48V & 5V?

The Vmp of the panels we are going to use is 33V, hence a total of 66V!

I look forward to your reply. Thanks.

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