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using CCA for solar:




I've bought a fair amount of 10ga CCA (copper-clad aluminum) wire and use CCA pretty exclusively for panel-side
wiring on my solar grid. I've had several people voice their concerns about the lossy nature of CCA, and how
I should be using pure copper ("OFC") for everything due to the high losses of CCA.

Keep in mind that the only disadvantages of CCA are higher resistance and lower power density. But for that,
you get a lighter cable at a third the price. You can transmit high power over CCA without significant losses as
long as you keep the voltage high and the current low.

This makes CCA impractical on the 12 volt side, since the current is high. But on the panel side, voltage is
much higher and current is much lower. My typical arrangement here is to set up several "solar frames", consisting
of 4 panels in series. These will develop up to 89 volts no-load, which drops down to 59 volts at maximum load.
The frames are connected together in parallel, which increases current but keeps the voltage the same. Each
frame can produce about 5 amps when receiving maximum sun and batteries are demanding a lot of recharge power.

Now since I connect the frames in parallel (since my mid-size controller can't handle over 90 volts) the current
will go up, but the reason I have more than 2 solar frames is NOT to get over 600 watts - the point of more panels
is so that I can collect more power when the sky is overcast, which lowers frame current. So most of the time,
panel current into the controller will be under 10 amps, and is often under 3 amps. Even if current losses start
to go up, the solar controller will see the drop in power on the 12v side and will adjust the conversion ratio on
the panel side, dropping current and raising voltage, which keeps transmission losses in check.

If we look at an example of say, 80 volts at 5 amps on the panels (producing 400 watts), 100 feet of #10 CCA
would only steal about 7 watts (2%), which just isn't worth the time and expense to try to lower to like 4 with
OFC. Doubling the power to 800 watts would probably quadruple the loss to 30 watts, but again, is it worth it?
Or can you afford to lose 30 watts, and settle for "only" 770 watts? Keep in mind, 100ft of CCA cost me $34,
and 100ft of OFC is over $100. An extra 4% just isn't worth $65 to me. And 2% most definitely is not.




last updated 03/22/2024 at 11:44:19 by make_www_index.command version 2024.03.14.B