Bungle
New Member
- Joined
- Feb 18, 2022
- Messages
- 1
Relative novice here (please see my profile background) - and sorry if this is a barrage of questions, but they're all kind of interrelated.
My questions center around sizing a load center for an off-grid solar shed. I plan to use 5920W of PV panels (16 Solarever 60-cell 370W panels in 8S2P), an MPP Solar LVX6048 unit, and a DIY-powerwall-style 18650 Li-ion battery bank. I have enough cells for up to ~30kWh and am slowly but surely building a bunch of 100-cell packs to use in a 14S configuration (so 50.4V nominal, but essentially 48V).
I'm unclear about how to think about the voltage and amperage coming out of the MPP Solar unit that feeds the load center. In the load center, I want to have one 240V/20A circuit for a table saw, and most likely three 120V/20A circuits for a dust collector, lights, and receptacles. Does that total 50A, because each of the 120V/20A circuits are essentially the same draw as 240V/10A? Am I thinking about that right?
If we assume that's correct (at least for the sake of argument), what would a reasonable main breaker size be? Is there some rule of thumb or standard ratio to determine that based on 50A total circuit size? Or would I be better off figuring actual maximum simultaneous load - say, table saw plus dust collector plus lights plus a fan or two - and sizing for that, plus a little extra for safety margin? Or does the 6000W maximum output of the MPP Solar unit just dictate that - i.e., 240V @ 25A = 6000W?
Lastly, based on the 6000W maximum output of the MPP Solar unit - can I assume that at 6000W, say 90% efficiency, I'd be drawing about 139A from the 48V battery ((6000W / 0.9) / 48V = 139A) on average, of course depending on actual voltage due to state of charge? Is it that simple?
If possible, some concrete numbers and/or examples/recommendations would probably help me to finally wrap my head around this. I will need to do some similar figuring at a larger scale for my off-grid house build, eventually.
Thanks so much!
My questions center around sizing a load center for an off-grid solar shed. I plan to use 5920W of PV panels (16 Solarever 60-cell 370W panels in 8S2P), an MPP Solar LVX6048 unit, and a DIY-powerwall-style 18650 Li-ion battery bank. I have enough cells for up to ~30kWh and am slowly but surely building a bunch of 100-cell packs to use in a 14S configuration (so 50.4V nominal, but essentially 48V).
I'm unclear about how to think about the voltage and amperage coming out of the MPP Solar unit that feeds the load center. In the load center, I want to have one 240V/20A circuit for a table saw, and most likely three 120V/20A circuits for a dust collector, lights, and receptacles. Does that total 50A, because each of the 120V/20A circuits are essentially the same draw as 240V/10A? Am I thinking about that right?
If we assume that's correct (at least for the sake of argument), what would a reasonable main breaker size be? Is there some rule of thumb or standard ratio to determine that based on 50A total circuit size? Or would I be better off figuring actual maximum simultaneous load - say, table saw plus dust collector plus lights plus a fan or two - and sizing for that, plus a little extra for safety margin? Or does the 6000W maximum output of the MPP Solar unit just dictate that - i.e., 240V @ 25A = 6000W?
Lastly, based on the 6000W maximum output of the MPP Solar unit - can I assume that at 6000W, say 90% efficiency, I'd be drawing about 139A from the 48V battery ((6000W / 0.9) / 48V = 139A) on average, of course depending on actual voltage due to state of charge? Is it that simple?
If possible, some concrete numbers and/or examples/recommendations would probably help me to finally wrap my head around this. I will need to do some similar figuring at a larger scale for my off-grid house build, eventually.
Thanks so much!
