thank you for explaining in simple words
power usage question
- Thread starter Dwight
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thank you for explaining
Hedges
I See Electromagnetic Fields!
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- Mar 28, 2020
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Battery voltage relates to how many watts of inverter is practical.
PV voltage to array power, and allows longer wires.
Large voltage delta between PV and battery does incur greater conversion inefficiency.
My system has 15kW 380Vmp array, AC GT PV 10kW coupled to 120/240V split-phase, with 23kW 48V battery inverters to form island grid in the event utility grid is down.
Smaller systems around 2kW AC could reasonably be 12V.
There are inexpensive 24V and 48V all-in-one inverters. Takes a twice as much battery to make minimum capacity 48V battery.
Some AIO (e.g. SolArk) are internally coupled PV --> HV DC, and HV DC <--> battery, <--> AC.
High voltage or AC coupled is particularly good when much power is used as it is produced (e.g. A/C).
PV direct to battery may be more optimum for off-grid systems with most loads at night.
PV voltage to array power, and allows longer wires.
Large voltage delta between PV and battery does incur greater conversion inefficiency.
My system has 15kW 380Vmp array, AC GT PV 10kW coupled to 120/240V split-phase, with 23kW 48V battery inverters to form island grid in the event utility grid is down.
Smaller systems around 2kW AC could reasonably be 12V.
There are inexpensive 24V and 48V all-in-one inverters. Takes a twice as much battery to make minimum capacity 48V battery.
Some AIO (e.g. SolArk) are internally coupled PV --> HV DC, and HV DC <--> battery, <--> AC.
High voltage or AC coupled is particularly good when much power is used as it is produced (e.g. A/C).
PV direct to battery may be more optimum for off-grid systems with most loads at night.
Hedges
I See Electromagnetic Fields!
- Joined
- Mar 28, 2020
- Messages
- 20,823
Both.
4x 12V batteries in series is 48V. But for lithium, we recommend a 48V battery, so one BMS controls all cells.
PV panels are nominally called 12V, 24V, 36V, but vary considerably with load. Typically 20V, 40V, 65V, 80V or so open-circuit.
You connect them in series so Vmp voltage is enough above max battery charging voltage for the SCC to work. But Voc never exceeds max allowed, even in cold weather. Typically 100V, 145V, 150V, 200V, 250V, 450V, 600V, 1000V.
Higher voltage charge controllers cost a premium, more $$ for fewer watts. Some panel voltages and current just don't fit some SCC well. So entire system design should be optimized before anything is purchased.
4x 12V batteries in series is 48V. But for lithium, we recommend a 48V battery, so one BMS controls all cells.
PV panels are nominally called 12V, 24V, 36V, but vary considerably with load. Typically 20V, 40V, 65V, 80V or so open-circuit.
You connect them in series so Vmp voltage is enough above max battery charging voltage for the SCC to work. But Voc never exceeds max allowed, even in cold weather. Typically 100V, 145V, 150V, 200V, 250V, 450V, 600V, 1000V.
Higher voltage charge controllers cost a premium, more $$ for fewer watts. Some panel voltages and current just don't fit some SCC well. So entire system design should be optimized before anything is purchased.
