Hey people. My reason for asking is below.

I had assumed the amount would be small (negligible) but want to
calculate the approximate difference in voltage drop between a "round
trip" of 20' and 23', 2/10 wire between panel and controller. It seems
there's more factors involved than I include here, but a double check
of my rough calculation would be appreciated.

Solar panel max. output: 7.9 Amps @ 18.99 Volts.

For #10 wire, using 1.24 Ohms per 1000'  ........

20' x 1.24/1000 = .0248 Ohms
23' x 1.24/1000 = .0285 Ohms

Using rounded off panel values:

.025 Ohms x 8 Amps  = 0.20 Volts
.029 Ohms x 8 Amps = 0.23 Volts

So adding 3' of wire(s) causes a voltage drop of 0.03 Volts?

My panel wires have MC4 connectors crimped on. I've emailed the vendor
for info, but hesitate to open the junction box on the panel as it may
be weather sealed. (had thought that end of the wire would be a
smaller OD)

Instead of drilling large holes for the MC4 connectors to pass through
the pop top, I'd like to drill one smaller hole and use the supplied
2/#10 FLAT cable that c/w the kit. I don't know if there's a  grommet
for that type of cable but am certain I can seal the hole well and
would do same even if a grommet was used.

Neil.

--
Neil n

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