MWeiss
New Member
- Joined
- Apr 22, 2020
- Messages
- 73
I bought forty 240W panels from Santan Solar in January. Have finally gotten around to deploying them and I'm noting dismal output levels when both 20 panel arrays are in full sunlight around noon-1pm.. I'm at 42° latitude.
I'm getting about 2kW from the southeast facing array and 1.4kW from the southwest facing array at the time when both arrays are in full sun and their outputs peak.
The array that's producing 1.4kW has a bad cell. I found that last night while checking the junction box bypass diodes. One panel has a short and is reading 1.6V instead of 9.8V that the the other two cell groups read. I pulled that diode thinking it was the diode, but no, it's the panel itself. That panel will have to be replaced. So I disconnected that panel and it's series companion for now.
I have the cells wired in series parallel, with ten groups of 2 in series, for a 48V nominal output for each array of 20 panels. These outputs are connected directly across my 48V battery bank's BMS outputs, so the BMS can shut down incoming charge if the voltage exceeds a set value.
I read about MPPT controllers and wonder whether directly connecting the panels to the batteries is creating a mismatch (similar analogy would be like connecting a 4 ohm speaker to the 8 ohm output of a vacuum tube amplifier--power transfer efficiency would be cut by about half) in load resistance to source resistance of the panels. Is it possible that putting a charge controller could double my panel efficiency, or are these used panels degraded to the point where over half their capacity is gone?
I'm getting about 2kW from the southeast facing array and 1.4kW from the southwest facing array at the time when both arrays are in full sun and their outputs peak.
The array that's producing 1.4kW has a bad cell. I found that last night while checking the junction box bypass diodes. One panel has a short and is reading 1.6V instead of 9.8V that the the other two cell groups read. I pulled that diode thinking it was the diode, but no, it's the panel itself. That panel will have to be replaced. So I disconnected that panel and it's series companion for now.
I have the cells wired in series parallel, with ten groups of 2 in series, for a 48V nominal output for each array of 20 panels. These outputs are connected directly across my 48V battery bank's BMS outputs, so the BMS can shut down incoming charge if the voltage exceeds a set value.
I read about MPPT controllers and wonder whether directly connecting the panels to the batteries is creating a mismatch (similar analogy would be like connecting a 4 ohm speaker to the 8 ohm output of a vacuum tube amplifier--power transfer efficiency would be cut by about half) in load resistance to source resistance of the panels. Is it possible that putting a charge controller could double my panel efficiency, or are these used panels degraded to the point where over half their capacity is gone?