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When I connect my PV (-) and (+) to my MPPT 100/50, my voltage immediately drops from 41V to 29V. This of course keeps the voltage too low for my 28V system to charge, so the charger stays "off".
I've replaced all MC4 connections between the panels and the MPPT just to be safe, yet the exact same voltage drop happens right when I connect to wires to the MPPT controller.
Firmware is updated.
Any thoughts on a potential solution?
It is normal for panel voltage to drop from VOC under load.
You basically need at least one more panel to work a higher string voltage thus taking advantage of the mppt.
The one panel setup works better with a pwm controller.
The voltage drop is normal under load, but yours seems slightly higher than what I would expect.
What is the rated voltage for maximum power for your panels?
How long are the wires from the PV panels to the MPPT and what size (cross-section area) are they?
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If you double the number of panels in series:
82V is probably fine, but if your string Voc gets too close to 100V, you have to check the maximum voltage for the lowest temperature you can have there.
I am with Seb the drop seems large for two panels. But then they are small panels if their VOC is around 20Vdc. More information is needed there.
Either there is something wrong or you have poor weather conditions. We comissioned some yesterday in the cloudy weather and we were getting 170VOC when the panels spec suggest we should see 212VOC in the string. But that is just the light conditions.
And run them through the mppt calculator. It will then show a graph on the page to give you an idea where the mppt will try and run when the panels are in the ideal circumstances. And if you will be over voltage in low temps if you add more panels.
