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I ran across a great deal on 10 gauge and 6 gauge stranded. I can get 100" for $20.00 and $24.00 respectively. Need to wire in 2 - 90 watt panels, a charge controller and 2 100 ah batteries. The problem is the charge controller will only take up to 12 gauge.
Questions are, is 6 gauge too big for the solar panel to controller run? Can I solder a short piece of 12 gauge onto the end of the 6 gauge to make the connections and still have the advantages of the 6 gauge.
Hi sl dl,
As you have already determined, the larger wire is more difficult to attach mechanically.
A wire run will drop voltage at it's end, not current. (E= I x R, if "R" goes up, "E" goes down) It's a voltage-dropping resistor.
AWG = American Wire Gauge (Copper wire)
AWG #10 wire will drop about 2-1/2 times more voltage than the AWG #6
The voltage drop across 6 inches, or even a foot, of AWG #12 can be ignored in this case.
The AWG #12 will limit your proposed run to a safe 20 amps. The AWG #12 will take more amps, but should be fused for a maximum of 20 Amps. (My opinion)
If your 2 90-watt panels can't produce a combined 20 amps, then I see no reason why you can't use that short section of AWG #12 and have the reduced voltage-dropping advantage of the much longer AWG #6 run.
24 cents a foot seems cheap for AWG #6. Use it. (If it's Copper)
I agree with Bill K. Use AWG #6 from the solar panels to the charge controller and the batteries. You have it and it will reduce voltage loss.
I will add that that sump pump, if it's an AC pump, will also be hard on your Inverter. An AC motor will have a tremendous current surge on start-up, which can be translated to surge watts the Inverter needs to be able to handle.
If it's an AC sump pump, look for a "locked-rotor" current rating on the motor nameplate. That should be the maximum amps that motor will draw before it heats up (very fast) and smokes. Fuses should be rated for less than that locked-rotor number.
The proposed Inverter should be able to handle "Watts= 120 vac x locked-rotor amps" for at least 2 seconds as its surge-output rating. Preferably more seconds. The seconds depends on how fast the motor can get up to operating speed. If you're not using a Pure Sine Wave Inverter, then the Watts=VxA formula will be inaccurate and can't be used.
If your Inverter has a "continuous output wattage" rating higher than the above formula results, then you're good to go after properly fusing the sump pump. Be careful about advertised ratings, which gets to be slippery.
Above all, design for safety.
Was planning to use 12v fans at the fireplace. I will build the system up to accomodate the sump pump. I want this system as a back up to the grid for that. already have 435 ah in batteries for the winter. (Summer 210 of that go to camp.) 225 ah will start the sump pump but not really well. Dpuble that should be fine; Also have a 4000w generator if I need it for a long time outage.
Don't have a GTI yet but will size according to pv output and load-stackable for future increaases. Plan more panels, and batteries. Want to set up small first and make my mistalkes there.
Thanks for the help.