12v MPPT and 24v MPPT vs 24v PWM Test
Got a chance to try out comparing amps to the battery using MPPT vs PWM on a 24v battery bank and comparing those with the usual MPPT on 12v with my 230w panel. The bank is four 6s, so it was easy ...
Forum Discussion
pnichols wrote:
Hmmmmmmm.
OK BF ... just for grins ignore your test results for a moment and Logic Me This:
If MPPT controllers both cost more and on top of that don't like hot panels, then why are they still around?
Something doesn't make sense here. Salvo may not be making his point well, but he might indeed have some kind of a point. :h
Because "MPPT" controllers have buck converters in them and "PWM" controllers do not. Never mind the tracking trick to get MPP, the thing is you need the buck converter to go 24-12, or 48-12, whatever.
You can only use a PWM controller when the panel voltage is the same as the battery voltage (nominally of course) and then you have to be careful it will do your voltages. Many PWMs will do either 24 or 12. You can get ones that will do 48, but mine won't.
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Salvo's curves above were taken with a 12v panel with the MPPT in 12v mode on a 12v battery. 12-12 is more efficient than 24-12 (as seen in my results and also the Morningstar graphs on that on their site.)
My results till today have been with MPPT 24--12 vs PWM 12-12.
I got the same results Salvo did for his "direct" using PWM on the same size 12v panel, which is as should be. I can't speak for what my MPPT would have done at the time, since I didn't try my Eco-worthy on my 130w panel in 12-12 when I had that panel.
We have to wait till July when I can get panel at 50C to see what really will happen on that score. I will do 24 vs 24 again to make it a fair fight :)
