3 ms·

What voltage do these µ/n-inverters produce? If everything is wired in parallel I assume it has to be fairly high to keep total current - and with that wire dim

What voltage do these µ/n-inverters produce? If everything is wired in parallel I assume it has to be fairly high to keep total current - and with that wire dimensions - down. This is an advantage of wiring panels in serial strings as that makes it possible to keep (copper) cable dimensions down to 4mm² or 6mm² for a 15kW installation like I installed on the barn roof a few years ago. The 18-panel strings can run at up to ~820V DC on a cold (-20°C) bright day which keeps the current down to a manageable ~9 A. In practice the string current tends to be higher and the voltage lower, normally somewhere around 12 A. What would this look like using those cell-level inverters? [edit] I see you partly answered this question in this thread already. Partly because that answer does not fit with the 'wire everything in parallel' mantra since that would necessitate all panels to produce exactly the same voltage to avoid power loss.

morphle 3y ago
We wire the solar cells in parallel to the MPPT nano-inverter chip (0.625 square milimeter). The 6V output of the inverters we can wire in series (we aggregate the voltage and current). 60 cells per panel gives 360V DC and 1.68 A output per panel. Normal panels where the cells are wired in series have around 36V DC and 15A per panel. So the thick 4mm² copper wires of a standard panel must be 8-10 times the wire thinkness of our panels. You can program the MPPT nano-inverter to output 6V AC and then aggregate to 360V AC. In this situation its better to output 110-120V AC in the US or 240V AC in most other parts of the world and feed this directly into the grid. The tricky part is the aggregation of the inverter outputs. The inverters each have different input voltage and current but must all output the exact same voltage to be agregated. The microcontroller have a network between all 60 inverters (122 in larger panels) so they can coordinate/balance their outputs. This is done at 100Kbps to 10 Mbps. The mosfet power transisters in the chip will switch at 100KHz to 1 Mhz to achieve the same ouput voltage.

morphle 3y ago

We wire the solar cells in parallel to the MPPT nano-inverter chip (0.625 square milimeter). The 6V output of the inverters we can wire in series (we aggregate the voltage and current). 60 cells per panel gives 360V DC and 1.68 A output per panel. Normal panels where the cells are wired in series have around 36V DC and 15A per panel. So the thick 4mm² copper wires of a standard panel must be 8-10 times the wire thinkness of our panels. You can program the MPPT nano-inverter to output 6V AC and then aggregate to 360V AC. In this situation its better to output 110-120V AC in the US or 240V AC in most other parts of the world and feed this directly into the grid. The tricky part is the aggregation of the inverter outputs. The inverters each have different input voltage and current but must all output the exact same voltage to be agregated. The microcontroller have a network between all 60 inverters (122 in larger panels) so they can coordinate/balance their outputs. This is done at 100Kbps to 10 Mbps. The mosfet power transisters in the chip will switch at 100KHz to 1 Mhz to achieve the same ouput voltage.