I have a solar well pump (DC) setup, been using it for 6+ years now. It has its own pump controller with a built in charge controller (PWM). It generally works well, but my 2 PV panels can't quite keep up with water needs in the summer. Temporarily I augmented the PVs with a 24v battery charger for a couple months last summer and it worked fine; so the water is there if I can get the extra power. The solution I am thinking of is to add a third PV panel (have a matching spare) to add some capacity for the summer months. Here are the details:
The PV panels are Canadian Solar 180W, Voc 44.5V Imax 5.4A. System is a nominal 24v; batteries are 24v AGM. Currently the two PV panels are wired in parallel. The pump controller could in theory take a third panel in parallel, but it would be right at the edge of its Imax limit (and maybe a hair over in ideal sun conditions). My thoughts were to bypass this PWM SCC in the pump controller and put in a separate MPPT controller to handle the charging of the batteries. With the right SCC this should allow me to put the panels in series to capture more low light power, and in general should be more efficient than the PWM controller which is in use now.
So to do this, I think I need a MPPT controller which can handle the three panels' Voc in series plus low temp headroom (~200v). Input current can be fairly low, likely under 6A, so maybe get 12 or 15A one just in case another panel is needed as 2s2p. And this controller will be mounted outside by the well head, so a weather-proof design would be needed. My search for such a controller has turned up nada; so I was hoping folks here might know of something which meets these requirements and is of decent quality. Any suggestions?
It would seem that putting 3 PV in series is going to get the max Voc up pretty high, especially for a small controller, and that might be making finding a SCC with these specs next to impossible. With an odd number of panels the only other option would be 3 in parallel. Which should work to 24v but will give up some low light power and efficiency. So I suppose that is my option B, an MPPT SCC with a 70-80v max input that can handle ~25A. (Or I suppose I could try just the current 2 panels in series to an MPPT controller and see if that improves power capture enough to handle the summer loads, (MPPT with 120v and 6A or 12A if expansion is called for).
Sort of thinking out loud here, but these are the ideas/choices I have been kicking around for this. Any ideas on a SCC, or other configurations which might have more HW available?
.
The PV panels are Canadian Solar 180W, Voc 44.5V Imax 5.4A. System is a nominal 24v; batteries are 24v AGM. Currently the two PV panels are wired in parallel. The pump controller could in theory take a third panel in parallel, but it would be right at the edge of its Imax limit (and maybe a hair over in ideal sun conditions). My thoughts were to bypass this PWM SCC in the pump controller and put in a separate MPPT controller to handle the charging of the batteries. With the right SCC this should allow me to put the panels in series to capture more low light power, and in general should be more efficient than the PWM controller which is in use now.
So to do this, I think I need a MPPT controller which can handle the three panels' Voc in series plus low temp headroom (~200v). Input current can be fairly low, likely under 6A, so maybe get 12 or 15A one just in case another panel is needed as 2s2p. And this controller will be mounted outside by the well head, so a weather-proof design would be needed. My search for such a controller has turned up nada; so I was hoping folks here might know of something which meets these requirements and is of decent quality. Any suggestions?
It would seem that putting 3 PV in series is going to get the max Voc up pretty high, especially for a small controller, and that might be making finding a SCC with these specs next to impossible. With an odd number of panels the only other option would be 3 in parallel. Which should work to 24v but will give up some low light power and efficiency. So I suppose that is my option B, an MPPT SCC with a 70-80v max input that can handle ~25A. (Or I suppose I could try just the current 2 panels in series to an MPPT controller and see if that improves power capture enough to handle the summer loads, (MPPT with 120v and 6A or 12A if expansion is called for).
Sort of thinking out loud here, but these are the ideas/choices I have been kicking around for this. Any ideas on a SCC, or other configurations which might have more HW available?
.
