Docvacuumtubes
RVF Newbee
- Joined
- Feb 7, 2026
- Messages
- 1
Very frustrating time trying to keep my new 21BHE grand designs solar system working. Just didn’t seem to charge lots of different times. Disconnecting the panels to test, mysteriously caused it to work again. (A Clue!!)
Turns out the problem was that they put the solar panel cut out switch between the MPPT controller and the battery—- not between the controller and the panels!
Like many charge controllers, this one needs to stay connected or at least be connected to the battery first, before being connected to the panels. So every time I flipped the solar panels switch, it got completely confused and refused to charge any further
I added a second switch that allows me to truly disconnect the controller from the panels on the roof, and it’s now easy to reset the system by turning both switches off and then turning the battery disconnect on first and then the solar disconnect on. The system then works properly and continues to work the next day as well.
The way mine was wired is not the way that the furion mppt controller manual says it should be done. By adding the additional switch, I solved that problem.
Gordon
Turns out the problem was that they put the solar panel cut out switch between the MPPT controller and the battery—- not between the controller and the panels!
Like many charge controllers, this one needs to stay connected or at least be connected to the battery first, before being connected to the panels. So every time I flipped the solar panels switch, it got completely confused and refused to charge any further
I added a second switch that allows me to truly disconnect the controller from the panels on the roof, and it’s now easy to reset the system by turning both switches off and then turning the battery disconnect on first and then the solar disconnect on. The system then works properly and continues to work the next day as well.
The way mine was wired is not the way that the furion mppt controller manual says it should be done. By adding the additional switch, I solved that problem.
Gordon
