Derating 24v Solar Panels?
I'm considering running two 250w/24v poly panels; tracked/pointed during spring/fall, and flat during the summer; thru the Tracer 3215BN 30a mppt controller. I can also get 200w/24v mono panels, local...
Forum Discussion
BFL,
I slept on it, and while sitting down by the beach this morning, it became obvious I need to keep things as simple as possible... but without eliminating my tilt 'n' twirl plans. So I'm looking to go with the two 24v panels, only (which is what I would have done originally, if planning a rooftop install, from the get go). But I cannot find 24v/200w poly panels to meet the Tracers 390w/12v bank rating.
Yes, I could simply go with a single panel, pointed, at times, but that would reduce peak amps to about 20a... less than what I'm seeing with the two 12v panels in series/mppt/pointed.
Usually I won't need every ounce of energy I can squeeze out of a single 24v/250w panel, in summer, but there may be times when I need to replenish Ah's quickly, or during/after a/c use. At these times I'd like to get the most out of the system, without taxing the controller too hard.
The panels I'm looking at are 60 cell... 6 rows of 10. My understanding is those 6 rows will be separated into 3 double rows of 10 (20 cells/section), by two diodes. So covering one cell would close down 20 cells, or 1/3 of the panel. Two 250w panels would therefore be de-rated to ~ 333w, for about 27a peak; perfect.
What I don't know is how (external) wiring effects things, if at all? Do the diodes operate differently if the panels are wired in parallel vs. series?
(I'll either keep the 12v system as a portable, or sell it.)
I slept on it, and while sitting down by the beach this morning, it became obvious I need to keep things as simple as possible... but without eliminating my tilt 'n' twirl plans. So I'm looking to go with the two 24v panels, only (which is what I would have done originally, if planning a rooftop install, from the get go). But I cannot find 24v/200w poly panels to meet the Tracers 390w/12v bank rating.
Yes, I could simply go with a single panel, pointed, at times, but that would reduce peak amps to about 20a... less than what I'm seeing with the two 12v panels in series/mppt/pointed.
Usually I won't need every ounce of energy I can squeeze out of a single 24v/250w panel, in summer, but there may be times when I need to replenish Ah's quickly, or during/after a/c use. At these times I'd like to get the most out of the system, without taxing the controller too hard.
The panels I'm looking at are 60 cell... 6 rows of 10. My understanding is those 6 rows will be separated into 3 double rows of 10 (20 cells/section), by two diodes. So covering one cell would close down 20 cells, or 1/3 of the panel. Two 250w panels would therefore be de-rated to ~ 333w, for about 27a peak; perfect.
What I don't know is how (external) wiring effects things, if at all? Do the diodes operate differently if the panels are wired in parallel vs. series?
(I'll either keep the 12v system as a portable, or sell it.)
