The optimal location for my planned solar array is 220 ft from my service panel in my cellar. This will be an off grid system connected to a Reliance switch box connected to selected circuits in my breaker panel, allowing me to switch between my solar and the grid.
I plan to start with a Magnum 4448 120/240 single phase inverter. The max 30 minute peak on this inverter is 5000 watts, so each leg would max at around 21 amps. Continuous rating would be 18.3 amps per leg.
I used an online voltage drop calculator and came up with 6 AWG wire size. It only gave the option to enter 1/2 the wire run length. I entered the full 220 feet. Using that parameter, I got the following results when combined with these additional parameters. The higher amp values were for the purpose of determining if I would have room for additional capacity to be added in the future. I wasn't quite sure which voltage / phase parameter to select, but the results were basically the same. I would assume the current flow through each individual conductor would be the main issue, but I could be wrong?
120V single phase @ 21 Amp = 4.4 volt drop to 115.5V
120V single phase @ 40 Amp = 8.4 volt drop to 111.6V 240 single phase @ 21 Amp and @ 40 amp gave the same respective voltage drops as above.
I welcome any comments on these results. I am fairly confidant I should be ok here, but am not sure if the 1/2 wire run parameter is compensated for by the calculator based on the selection of AC or DC voltage, so I entered the full 220 feet since it will be AC.
Also if I up my capacity to the 40 amps, will I be ok with the resulting 111.6V per leg as far as devices that may be sensitive to lower voltages? My house wiring is all 12GA, so additional drop between breaker panel and load should be minimal.
Lastly, I am going to use THNN cable buried in conduit. Am I correct in thinking I will not need to run an earth ground, just my 2 hots and a neutral? Can I get away with a smaller diameter neutral or does it also need to be 6AWG? I saw a price of $.60/ft for this size wire, so if I can keep the cost down with a smaller neutral and stay within code that would be good.
Thanks,
Crispy