? watts through a #6 wire

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Hi guys & Gals;

As mentioned before father and I have come to an agreement, I can
mount my apanels on the garage. The wire run from the garage will be
about 100 to 120 feet, I have #6 wire (already installed) and I was
wondering, how much current (at 12 volts) can I safely put through my
wire before resistance becomes an issue?

I only have 290 watts right now but I will be adding 2 more 50 watt
panels each month until November.

Should I switch to a 24 volt system, which would also help with line
loss.

Any advice would be greatly appreceated, and keep smilin'
Glenn

PS. The roof is about a 35 degree angle, so I was wondering, what
about snow?

 

[Gary]

Hi guys & Gals;

As mentioned before father and I have come to an agreement, I can
mount my apanels on the garage. The wire run from the garage will be
about 100 to 120 feet, I have #6 wire (already installed) and I was
wondering, how much current (at 12 volts) can I safely put through my
wire before resistance becomes an issue?

I only have 290 watts right now but I will be adding 2 more 50 watt
panels each month until November.

Should I switch to a 24 volt system, which would also help with line
loss.

Any advice would be greatly appreceated, and keep smilin'
Glenn

PS. The roof is about a 35 degree angle, so I was wondering, what
about snow?

Hi,

The resistance of #6 COPPER wire is 0.403 ohm per 1000 ft,

So the resistance of your run (roundtrip) is:

(0.403) ((120 + 120)/1000) = 0.097 ohm

The current for 290 watts at 12V is 290/12 = 24.2 amps

The voltage drop is:

E = IR = (24 amp) (0.097 ohm) = 2.3 Volts (or about 20% of 12V)

I don't know much about PV panels, but 20% seems like a lot to give up?

The voltage drop would increase linearly with current, so 580 watts of
panels would give a voltage drop of 4.6 Volts ... etc

Since #6 TW wire is only rated for about 55 amp, I think you would also
have a safety issue before all of your panels are in.

You probably need bigger wires, and/or a panel connection that gives a
much higher output voltage.

---
On the roof slope, I have a 45 deg south facing slope in snow country,
and it does not accumulate snow -- it melts off soon after snowfalls.
The North and East slopes do accumulate quite a bit of snow.

Gary

 

[SQLit]

Hi guys & Gals;

As mentioned before father and I have come to an agreement, I can
mount my apanels on the garage. The wire run from the garage will be
about 100 to 120 feet, I have #6 wire (already installed) and I was
wondering, how much current (at 12 volts) can I safely put through my
wire before resistance becomes an issue?

I only have 290 watts right now but I will be adding 2 more 50 watt
panels each month until November.

Should I switch to a 24 volt system, which would also help with line
loss.

Any advice would be greatly appreceated, and keep smilin'
Glenn

PS. The roof is about a 35 degree angle, so I was wondering, what
about snow?

When dealing with dc voltages, I use MTW or welding cable. Machine tool wire
is a lot finer strands and tends to carry a tad better than regular stranded
wire. Welding or locomotive cable is by far the best you can get. Also the
most expensive. I think you should really start considering increasing the
wire size and going to a higher voltage.

 

[[email protected]]

Hi Guys & Gals;

While I might not understand all the advice (still learning and loving
it), would it be better if I put my batteries, regulater and inverter
in the garage and ran a line from my inverter into my house? Could I
use the #6 (copper) wire that I already have installed. Just a
thought.

Once again, thanks for the advice and keep smilin'

Glenn