I was helping a neighbour with his DIY MN3024 when I noticed a behaviour I couldn't explain.
The DIY seems to pull the solar array voltage down to 36V at dawn most of the time.
The array Voc is around 80V+ and the Vpmax is around 70V.
As the sun gains strength the charge current climbs but the diy continues to drag the PV input down to 36V. The system works but doesn't make use all the available power.
In this "broken state" - PV IN is always 36V - so there is something special about that value.
The DIY can be kicked out of this state by:
- restarting the diy
- Running the generator momentarily (Charger Source = Mains Priority)
- Disconnecting and reconnecting the array.
The PV will go to 80V and then the DIY will pull the PV IN down to about 68V and the charge current will climb to 30+ Amps - basically the max capacity of the array.
Once in its state the system will perform as expected until the next morning.
Occasionally the system works as expected. I am not sure if there weather sun/cloud conditions made the difference.
We tried another PV array out of different panels - but the result was the same.
I am hoping there is a setting that is wrong that is causing this behaviour.
We are in a "gloomy" part of the world so while it isn't a big issue in the height of summer- in the other seasons every watt matters.
Application: Off-grid. PV is the primary source with a small backup generator.
Array: 6x175watt
Vpmax = 2x35.4 approx 70V
Ipmax = 3x4.95 Approx 15A
DIY Settings
Parameter:
01 - Output Source Priority - UTI (default) - Mains priority
06 - Charger Source Priority - CUB - Mains Priority (Tried SNU or hybrid but no difference)