Forum Discussion
BFL13
Jan 07, 2015Explorer II
When people use "performance" to mean more watts instead of more amps, there is no point in arguing. Batteries use amps not watts.
Then you get two different scenarios. Solar more to run loads and solar more to charge batteries. Then you divide the world into those who use solar all year and those who only use it in the summer.
I mostly run my loads from the batteries and then recharge with solar using amps and do that only in the warm sunny half of the year.
The season where and when we use solar has panel temps that go from 44C, when MPPT gets more amps than PWM, to 51C when my PWM gets more amps than my MPPT. By actual measurements.
You have to arrange things to suit yourself in your own situation and that means you can only cherry-pick from somebody else's arrangements for the parts that would suit you.
EG, I use my single 230w and MPPT the whole season because that's what I have even though most of that season PWM would get me more amps (12v panels cost way more here than 24v panels and I didn't know about this until after I got the MPPT)
I don't get more AH by using MPPT in low light so much either since in the summer-like situation it is either nice out or not. So it does not average out for the day. ( People have claimed that the PWM might get that extra amp or two at noon, but over the whole day the MPPT would get more AH. Not for me from what measurements I have, but it might happen for others in other situations)
So I know from trying it both ways and comparing in the same situation, if not for the money (12vs vs 24s) I would do better in amps and AH to the battery with two 12s than one 24. I would go MPPT in series for the Spring and swap to PWM in parallel for the Summer and then go back to MPPT in series for the Fall.
No need to do all that anyway, because the 230w and MPPT meets all our needs. I still do miss those "wasted" and "lost" amps MPPT is "costing me" though, even though they aren't needed :)
Then you get two different scenarios. Solar more to run loads and solar more to charge batteries. Then you divide the world into those who use solar all year and those who only use it in the summer.
I mostly run my loads from the batteries and then recharge with solar using amps and do that only in the warm sunny half of the year.
The season where and when we use solar has panel temps that go from 44C, when MPPT gets more amps than PWM, to 51C when my PWM gets more amps than my MPPT. By actual measurements.
You have to arrange things to suit yourself in your own situation and that means you can only cherry-pick from somebody else's arrangements for the parts that would suit you.
EG, I use my single 230w and MPPT the whole season because that's what I have even though most of that season PWM would get me more amps (12v panels cost way more here than 24v panels and I didn't know about this until after I got the MPPT)
I don't get more AH by using MPPT in low light so much either since in the summer-like situation it is either nice out or not. So it does not average out for the day. ( People have claimed that the PWM might get that extra amp or two at noon, but over the whole day the MPPT would get more AH. Not for me from what measurements I have, but it might happen for others in other situations)
So I know from trying it both ways and comparing in the same situation, if not for the money (12vs vs 24s) I would do better in amps and AH to the battery with two 12s than one 24. I would go MPPT in series for the Spring and swap to PWM in parallel for the Summer and then go back to MPPT in series for the Fall.
No need to do all that anyway, because the 230w and MPPT meets all our needs. I still do miss those "wasted" and "lost" amps MPPT is "costing me" though, even though they aren't needed :)
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