question

guenno avatar image
guenno asked

MPPT 250/100 doesn't show correct PV generator voltage

I tried to find an answer in the forum after reading the documentation. But no headline/topic seams to answer my question.
If my generator isn't connected to the MPPT 250/100 I can measure 79V. So this is more than 53V and it should load the battery.
When I connect the generator cables (polarity is checked) to the MPPT, I can only messure 49.1V at the PV screws.
The same value is shown at the Battery screws.
Bulk is flashing slowly. The MPPT is cool.

The US3000C wild not be charged.

Please can you help me to solve that problem?

sketch-of-config.png

screenshot.png

MPPT Controllers
sketch-of-config.png (349.8 KiB)
screenshot.png (84.6 KiB)
2 |3000
Toggle Comment visibility. Current Visibility: Viewable by all users

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

3 Answers
Alexandra avatar image
Alexandra answered ·

@guenno

You have a 250/100. You need to increase the pv input voltage to closer to that otherwise you are wasting it.

Under load the voltage drops so you want to start with at least 3x battery voltage voc

You can easily you must have a 2s 3p setup.

Try 3s 2p. or if the VOC allows 6in a string.

Check if that is allowed with your panel specs on the victron mppt calculator.

https://www.victronenergy.com/mppt-calculator

2 |3000
Toggle Comment visibility. Current Visibility: Viewable by all users

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

seb71 avatar image
seb71 answered ·

79V (with no load / open circuit) for 3 370W PV panels in series seems low.

I would expect at least 100V (if there is Sun and no shadows).


Maybe there is something wrong with one panel or with the connection.

Check the connections and try with only one string.

2 |3000
Toggle Comment visibility. Current Visibility: Viewable by all users

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

guenno avatar image
guenno answered ·

Sometimes you get in each other's way.
Experience is helpful.
I have now moved the panels outdoors, where the lighting conditions are better, although the volts are not dramatically higher.
In any case, it works now :-)
Many thanks to @Alexandra and @seb71 !!!!
I had completely lost my way.

2 |3000
Toggle Comment visibility. Current Visibility: Viewable by all users

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