Correct wire sizes are essential

To connect the components of a Solar Energy System, you will need to use correct wire sizes to ensure low loss of energy and to prevent overheating and possible damage or even fire. Below is a chart showing the required wire size for wire lengths to connect the solar panels to the charge-controller Use these numbers for a 12 volt system to achieve a 3% or less voltage drop.
	The top row represents the Wire gauge size, the left column the number of amps the solar panels are rated at, and the grid cells show the distances in feet between the Solar Panels and the Charge Controller.
For example: If you have 3 solar panels rated at 6 amps each, mounted 30 feet from the Charge Controller, then you would move down the chart to 18 amps (3 panels * 6 amps), and across to 32.5 (closest to 30), and then up the chart to #4. You would need at least #4 gauge wire (awg) to move 18 amps 30 feet with a minimum voltage drop of 3% or less, an acceptable loss. If you can't find the exact numbers, choose either a larger gauge wire (smaller number) or select a distance longer than your actual distance.
Wire chart for connecting 12 Volt solar panels to the Charge Controller
This chart shows wire distances for a 3% voltage drop or less. These distances are calculated for a 12 volt system. Multiply distances by 2 for a 24 volt system. Multiply distances by 4 for a 48 volt system.
#12 #10 #8 #6 #4 #3 #2 #1 #1/0 #2/0   4   22.7 36.3 57.8 91.6 146 184 232 292 369 465 6   15.2 24.2 38.6 61.1 97.4 122 155 195 246 310 8   11.4 18.2 28.9 45.8 73.1 91.8 116 146 184 233 10   9.1 14.5 23.1 36.7 58.4 73.5 92.8 117 148 186 12   7.6 12.1 19.3 30.6 48.7 61.2 77.3 97.4 123 155 14   6.5 10.4 16.5 26.2 41.7 52.5 66.3 83.5 105 133 16   5.7 9.1 14.5 22.9 36.5 45.9 58.0 73.0 92.0 116 18   5.1 8.1 12.9 20.4 32.5 40.8 51.6 64.9 81.9 103 20   4.6 7.3 11.6 18.3 29.2 36.7 46.4 58.4 73.8 93.1 25   3.6 5.8 9.3 14.7 23.4 29.4 37.1 46.8 59.1 74.5 30   3.1 4.8 7.7 12.2 19.5 24.5 30.9 38.9 49.2 62.1 35   2.6 4.2 6.6 10.5 16.7 20.9 26.5 33.4 42.2 53.2 40   2.3 3.6 5.8 9.2 14.6 18.4 23.2 29.2 36.9 46.5
Connecting the Charge Controller After you connect the Solar Panels to the input terminals of the Charge Controller using the above chart, you can use the same size wire to connect the Charge Controller output to the batteries since these wires will carry no more current than the solar panel wires and will probably be located pretty close to the batteries anyway. Connecting the Power Inverter The power-inverter is next. Both the Power Inverter and the Batteries require the largest wires in the system. During operation, the AC produced by the Power Inverter draws considerable amps from the batteries. Not only are very large wires required, but they should not exceed 6 feet in length to reach the batteries. These wires are like the large battery cables in cars. Use the largest size possible. An AC appliance drawing 10 amps (like a microwave or vacuum cleaner) will require 100 amps at 12 volts DC. Even large cables will get warm. Don't skimp here.

Connecting the Batteries The batteries are last. They will also require very large cables like the large battery cables in cars. The full current to the loads and also the full charging current flow thru the entire battery bank. Connect all the batteries with large high quality cables. 

Battery wiring diagrams
The following diagrams illustrate how to get increased current (more power) by using parallel wiring and how to increase voltage levels by using series wiring. You can do both using series and parallel wiring in combinations.
Use parallel wiring to increase current (power).
	This diagram shows a simple parallel circuit to increase current or power. Assume that we are using 12 volt batteries. The power of all 3 batteries add to give us the effect of a battery 3 times as powerful but the voltage stays the same at 12 volts. Parallel wiring increases current but the voltage does not change. This is the wiring used when jump starting a car for example.
Use series wiring to increase voltage
This diagram shows a simple series circuit to increase the battery voltage level. Assume that we are using really big 4 volt industrial batteries.
The voltage of all 3 batteries add to give us the effect of a battery 3 times the voltage or in this case a very large 12 volt battery. In this circuit the current is the same as the current in just 1 of the batteries. But since the 4 volt industrial batteries are very large, we have in effect created a huge 12 volt battery.
Use series & parallel wiring in combination
This diagram shows a combination series and parallel circuit to increase both the battery current and voltage level at the same time. Assume this time we are using 12 volt batteries.
The left to right series connection add the two 12 volt batteries to make 24 volts. And, since we did this 3 times and then connected each group of 2 (now 24 volts) in parallel we end up with one very large 24 volt battery. It has twice the voltage of a single 12 volt battery and 3 times the current or power because all 3 groups are wired in parallel.
The sky's the limit So, using series wiring, you can build up the voltage to the level you need and using parallel wiring you can increase the current or power. For example, you could setup a 24 volt battery bank by connecting two 12 batteries together in series or create a 48 volt battery bank by connecting four 12 volt batteries in series. Then just repeat this until you get the power you want and put all those now 24 or 48 volt groups in parallel. Batteries for solar power systems are available in 2, 4, 6, and 12 volts, so any combination of voltage and power is possible.

DISCLAIMER : Alway make sure that all of your equipment is properly fused and grounded for safety. Also, be sure to read and follow the advice and instructions that come with your equipment. While projects have actually been constructed and tested under actual operating conditions, we do not guarantee that they will meet all electrical codes in all locales. Nor do we suggest that our advice supercedes the recommendations of a licensed electrician. Hey, we're just trying to help!