Mounting solar maintainer 25' from battery, what wire size?

[dh]

One of my projects this summer is a car port on the back of my property for the trailers (trailerport?). I was going to run electric to it from the house for a light and an outlet for a maintainer, then got to thinking, why not go solar? The shed light kit is a no brainer, but I want to put the maintainer pannel on the roof which slopes to the south. What size wire do I need for a 25' run?

[rdelmendo]

Hi dh-

Robert at AZ Wind & Solar recommended 10 gage for my panel. I think this was for up to 30' or so feet (we were discussing the +/-'s of using movable PVC ground mounts for the panel).

Cheers,

Ron

[bdosborn]

Wire should be sized by how much load it will be carrying. How big is your panel?

Bruce

[Dale M.]

Wire should be sized by how much load it will be carrying. How big is your panel?

Bruce

Yes .... Need specifics on panel and ancillary apparatus...

If its only for maintenance and output of panel is only a couple of amps, you can get away with something like 14 gauge wire...

Dale

[dh]

I don't have the pannle yet, but know maintainers don't put out a lot of power and was more concerned about power loss from too small of a wire being run.

[azmotoman]

There are many places on the internet for 'line drop' charts and calculators. Here's just one: http://www.powerstream.com/Wire_Size.htm

The calculator is near the bottom of the page.

[dh]

Thanks for the link

[Shadow Catcher]

Ifn it twere me, I would head down to HF and pick up a 12ga extension cord and use that. Having spent over $100 on rewiring Compass Rose do not go over board.

[bdosborn]

A #12 cord would be good for 4 amps at 2.8% voltage drop for 25'. A good target for voltage drop is 3% or less.

Here's a better VD calculator.

http://www.nooutage.com/vdrop.htm

You can pick 14V DC for the voltage, which is closer to what the voltage will be between the panel and a PWM controller.

Bruce

[dh]

Is it possible to go with too big of a wire? Just for fun, lets say I ran an 00 battery cable, what would happen?

[terryjones1]

Is it possible to go with too big of a wire? Just for fun, lets say I ran an 00 battery cable, what would happen?

Ohms law still applys.

E = I R

Voltage = Current x resistance

If you have larger cable, resistance is lower. If you have lower resistance, the voltage drop will be less.

Other than being rather large & heavy, 00 cable would be much better for voltage drop losses.

[bdosborn]

Is it possible to go with too big of a wire? Just for fun, lets say I ran an 00 battery cable, what would happen?

Your wallet would get much lighter for about a piddly 2% increase in performance. That's why you shoot for around 3% voltage drop; its a good balance between price and performance.

Bruce

[dh]

Thanks for the replies.