We have 4 solar panels mounted on the bimini of our boat 2 in series and then parallel to 1 epever mppt charger. We measure a voltage from the panels with the multimeter of around 34, which seems fine. But as soon as we connect the cables to the mppt the voltage the mppt shows is going down to around 14 . We don t have a clue why. Any tips?
Mppt shows too low voltage input for panels placed in parallel
- Thread starter Marelief
- Start date
sunshine_eggo
Happy Breffast!
Link MPPT.
I’m trying to understand what panels you have 2s and only getting 34V…
Even cheapo “12V” panels output over 20VOC so, 34 seems low. Perhaps you have some shade on the panels?
Even cheapo “12V” panels output over 20VOC so, 34 seems low. Perhaps you have some shade on the panels?
Warpspeed
Solar Wizard
I have seen a similar effect myself, and the exact cause is still a bit of a mystery.
But what I did was connect a diode in series with each series string of panels before the outputs are combined, and that seemed to fix it.
I suspect it might have something to do with partial shading of one or more panels. The voltage in one string falls, and that loads down the other string.
The mppt software will still heroically try to find the power peak, but it pulls the voltage right down in the process.
With diodes fitted everything then worked as expected. The power peak coincided pretty well with the voltage on the rating plate.
There may be some other mysterious mechanism at work, but diodes certainly solved the problem here.
Anyhow, its worth a try.
But what I did was connect a diode in series with each series string of panels before the outputs are combined, and that seemed to fix it.
I suspect it might have something to do with partial shading of one or more panels. The voltage in one string falls, and that loads down the other string.
The mppt software will still heroically try to find the power peak, but it pulls the voltage right down in the process.
With diodes fitted everything then worked as expected. The power peak coincided pretty well with the voltage on the rating plate.
There may be some other mysterious mechanism at work, but diodes certainly solved the problem here.
Anyhow, its worth a try.
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