question

henrique-eipeldauer avatar image

Acceptable Controller for my PV Array?

I'm having 2x150W (Vmp=17.9V and Imp=8.4A) panels installed IN SERIES to my boat (12V batteries), which is much more energy than I need.

I plan to use MPPT 100/20, which is limited at 290W in its input and 20A at its output.

Victron's spreadsheet calculator shows at 25C a theoretical maximum output current (at MPPT) of 24.5A, limited to 20A.
At 5C, this same current would go up to 26.2A.

I'm totally OK with not being able to use the full 300W power of my panels (MPPT limit=290W).
But my concern here is possibly causing some long term damage to the controller by exploring this 20A output limit too often.
Should I avoid this situation to keep the controller safe and healthy?

Thank you!

mppt smart solar
2 |3000 characters needed characters left characters exceeded

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

1 Answer
wkirby avatar image
wkirby answered ·

It is fine to run the controller a the 20A limit. In reality it will not meet this every day, like cloudy days.

Of course there is also the option to configure a lower output current limit within the settings.

3 comments
2 |3000 characters needed characters left characters exceeded

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

Thank you for your answer, wkirby!

Unless I needed to configure a lower output current for controller health/safety reasons, I wouldn't have any benefit in setting it lower than 20A.

If it won't harm the controller running it at its max current, I'll just leave the limit to its maximum 20A.
As you correctly mentioned, it would only happen sometimes, because of shading, panel angle, cell temperature, etc.

wkirby avatar image wkirby ♦♦ henrique-eipeldauer ·

Just worth adding that you should mount the controller so that it has adequate cooling.
It will get warm at full output current, proper cooling will keep it within safe temperature bounds.

I have a few of my own controllers which see full output current like this, they have a few MWh through them over the years, no issues at all.

Thank you once again, wkirby!
Your own experience with your controllers is encouraging.
I'll go ahead with the 100/20 and make sure it's well cooled.