Sunday, July 17, 2016
Solar System Wiring, Bigger is Better!
Is bigger wire gauge better? For low voltage DC, Yes! Get every watt you can from your system by simply using bigger wires.
I wanted to find out if bigger gauge wires really made a difference with the amount of amps delivered to the batteries.
My System as First Set-Up:
Is a simple 200 watt system, two 100 watt panels, similar to what is being used by van-dwellers and RV’s. My controller is 12 feet from the panels and by most wire size charts available allow the use of #10 wire from the panels to the controller. The wire used from the controller to the batteries was #8.
My System Re-Wire:
I kept the length of wires the same but used #4 welding cable from the panels to the controller and #4 wire from the controller to the batteries. #4 cable was used to keep the voltage loss to a minimum. All connections are made with typical ‘crimp style connectors’.
Most hardware and big box stores have a good selection of connectors for #4 wire. The use of ‘welding cable’ is not necessary, but it’s far more flexible and easy to work with than household stranded wire at only a few cents more per foot.
The Results are Stunning:
I actually ‘Doubled’ the amps to my batteries just by using the larger gauge wire! I now have 68 amps of useable power everyday to run fans, lights, radio, TV, recharge my ‘AA’ Batteries and even a 12v refrigerator. For test comparison accuracy I used a 750 watt electric heater for a few minutes at a time to maintain a 12.2 volt battery state of discharge between the hours of logging the results.
The chart below shows the amps to the battery readings on clear sunny
days. The chart shows the hour of day and the delivered amps using #10 wire compared with using #4 wire and the amps delivered at the same hour of day: Florida
Time #10ga #4ga
7:00am 0.0 0.0
8:00am 0.2 1.1
9:00am 0.3 1.9
10:00am 2.1 4.2
11:00am 4.0 8.8
12:00pm 5.0 9.7
1:00pm 5.6 12.0
2:00pm 5.1 10.2
3:00pm 4.2 8.1
4:00pm 1.7 6.0
5:00pm 1.5 4.1
6:00pm 0.3 2.0
7:00pm 0.0 0.0
Results: 30.0 vs 68.1 Total amps delivered for the day.
Large wire sizing and solid connections are critical to get every watt from your solar panels and may save you from buying unnecessary panels to deliver more amps.