Solar-Panel to Controller Loss
Much has been made of the lower losses on the panel to controller path with MPPT because the amps are less. So once you have your loss measured, how valuable is it to improve on that if you don't lik...
Forum Discussion
That was not just one time. I got the same thing with the 255w panel as reported in this thread earlier.
As to the all day higher average AH haul for "MPPT" that is apparently more to do with the higher voltage above battery voltage they have with 24-12 than the PWM at 12-12, even when panel voltage is low, such as in low light and earlier/later in the day. That could be more (if true) with a 72 cell panel vs a 60 cell too.
Since my test was at 24-24 with both, there was no voltage advantage for the MPPT. There might still have been an advantage for the MPPT due to its tracking of the max power point, but this did not show, perhaps because that was countered by the buck converter loss in the MPPT that the PWM doesn't have.
You can't do 24-12 with PWM so there is no way to swap controllers and check that against 24-12 MPPT
The 12-12 PWM results I got for max amps comparison was the Isc of the panel. Eg, a 230w would do 230/130 x 8.2 = 14.5 amps (in proportion to my 130w panel's output, which is my standard for comparing amps results)
With 230w panel temp of 44C, I got 15.5 amps with 24-12 MPPT vs that 14.5 for 12-12 PWM, but only 13.5 amps at panel 50C. I wanted to get at least that 14.5 with a hot panel or else I might as well have 12v panels and PWM (ignoring prices)
I would expect 255/130 x 8.2 = 16 amps with 12-12 PWM, so the 17 amps I got with 24-12 MPPT at 45C panel is consistent with my earlier results with the 230w panel at 44C, being slightly better in amps than what 12-12 PWM would do.
Unfortunately, the 255's 9.0 amp Isc which would be equivalent to 18 amps at 12v, did not happen with PWM at 24-24. So already my scheme to use 24-24 PWM is in trouble, perhaps because I am comparing 36 cell 12-12 with 60 (vs 72) cell at 24-24, don't know.
This is all about getting at least as good an amps output from the 24v panel when it is at 50C as you can get with 12-12 PWM.
So far at 24-24, at panel 45C, using 230w and 255w 60 cell panels, MPPT and PWM are equal for max amps output.
We will see what happens at 50C panel, if the PWM 24-24 can at least do the 16 amps that 255w of 12-12 PWM can do even if it can't do the 18 (9 at 24) I was hoping for.
As to the all day higher average AH haul for "MPPT" that is apparently more to do with the higher voltage above battery voltage they have with 24-12 than the PWM at 12-12, even when panel voltage is low, such as in low light and earlier/later in the day. That could be more (if true) with a 72 cell panel vs a 60 cell too.
Since my test was at 24-24 with both, there was no voltage advantage for the MPPT. There might still have been an advantage for the MPPT due to its tracking of the max power point, but this did not show, perhaps because that was countered by the buck converter loss in the MPPT that the PWM doesn't have.
You can't do 24-12 with PWM so there is no way to swap controllers and check that against 24-12 MPPT
The 12-12 PWM results I got for max amps comparison was the Isc of the panel. Eg, a 230w would do 230/130 x 8.2 = 14.5 amps (in proportion to my 130w panel's output, which is my standard for comparing amps results)
With 230w panel temp of 44C, I got 15.5 amps with 24-12 MPPT vs that 14.5 for 12-12 PWM, but only 13.5 amps at panel 50C. I wanted to get at least that 14.5 with a hot panel or else I might as well have 12v panels and PWM (ignoring prices)
I would expect 255/130 x 8.2 = 16 amps with 12-12 PWM, so the 17 amps I got with 24-12 MPPT at 45C panel is consistent with my earlier results with the 230w panel at 44C, being slightly better in amps than what 12-12 PWM would do.
Unfortunately, the 255's 9.0 amp Isc which would be equivalent to 18 amps at 12v, did not happen with PWM at 24-24. So already my scheme to use 24-24 PWM is in trouble, perhaps because I am comparing 36 cell 12-12 with 60 (vs 72) cell at 24-24, don't know.
This is all about getting at least as good an amps output from the 24v panel when it is at 50C as you can get with 12-12 PWM.
So far at 24-24, at panel 45C, using 230w and 255w 60 cell panels, MPPT and PWM are equal for max amps output.
We will see what happens at 50C panel, if the PWM 24-24 can at least do the 16 amps that 255w of 12-12 PWM can do even if it can't do the 18 (9 at 24) I was hoping for.
