Luca Colangiuli avatar image

Clarification on minimim panel voltage for smartsolar mppt

Hi, i’ve on my van a 100w panel that output normally about 17/18. I don’t have the panel details as it was already installed on the van.

I’ve installed a smartsolar 100/20 mppt controller and a 100ah agm battery.

If i connect to the mppt via bluetooth i see that panel voltage is 15.79v and battery voltage 12.54

Battery state says “shutdown” (i guess this is the right translation, my app is in italian)

On the manual i read that:

● PV voltage must exceed Vbat + 5V for the controller to start. Thereafter minimum PV voltage is Vbat + 1V.

So if i’ve understood correctly if the panel voltage remain the same the smartsolar will start charge the battery only if it reach 10.79v, i’m right?

If this is correct probably it is bettee for me to reinstall the old pwm charger or to change the solar panel with an higher voltage one.

can someone help me on this?

thanks in advance,


MPPT Controllersbattery chargingsmart solar set-up help
2 |3000

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

1 Answer
Guy Stewart (Victron Community Manager) avatar image
Guy Stewart (Victron Community Manager) answered ·

You are correct, where panel voltage is only a few volts higher than battery voltage, a PWM controller is better.

MPPT takes advantage when panel voltage is 2+ times higher than battery voltage, and 5V is the absolute minimum.

Update - @Johannes Boonstra (Victron Energy Staff) from Victron has made a short video that explains this in further detail - Q&A: Why does the Victron Energy MPPT starts 5Vdc above the battery voltage?

2 |3000

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

That would be fine as long as it doesn’t get too cold, so would most panels available at 300W+

There is a tool here that will tell you if a panel is suitable for your MPPT:

Once over the 5V threshold, the other important value is that the maximum voltage the MPPT ever sees is less than the rating. In your model, 100V.

The calculator will make sure the voltage stays under that in your temperature range.