Solar Regulator Charging System - Wire Sizing Calculator

This calculator will help you understand the factors involved in sizing wires for a solar regulator charging system. Before you start you will need to know

• the running voltage of your system
• the rated power of your solar panels and load
• the three pair cable length runs for all wire sections to the regulator shown below

You'll need to use the sizing calculator to size each wire length as follows:

Solar to Regulator Wire

For this length voltage drop is not critical as the regulator can deal with voltage variations, however the power loss should be kept to less than ~3-5%.

Battery to Regulator Wire

For this length voltage drop is critical as the regulator supplies very specific voltages to charge your battery. A large voltage drop in this wire would affect the charging voltages your battery receives and hence may affect battery life. You should keep this wire short, with voltage drops less than 0.25V for 12V system (or 0.5V for 24V). You also need to size this length of wire so that it can handle the maximum drawing load on the battery if you are planning on connecting the load through your regulator and not direct to the battery.

Load to Regulator Wire

For this length you should consider power loss and the Ampacity of the wire as some loads can draw a substantial current from a battery.

§ For the Solar to Regulator wire run use 1.3 × the rated wattage power of the solar panels. For the Battery to Regulator and Load to Regulator wires use the maximum power draw of your load.
* Distance to the regulator - the calculator will multiply this distance by two to get the total positive and negative copper wire length.
† This is the cross sectional area of the copper wire.
‡ Ampacity: is the maximum amount of current a wire (installed in an open ventilated area) can carry before sustaining progressive deterioration. Warning! A section of wire running through highly insulating materials (such as pink bats /glass wool ect...) will have a much lower Ampacity!

You can also size your solar panels using our off-grid solar panel sizing calculator. You can also size your solar charging regulator by using our solar regulator sizing calculator.

Disclaimer: This free to use calculator is provided as is. While we have endeavoured to make this calculator as accurate as possible we take no responsibility for accuracy of the assumptions, data or advice it provides. This calculator should be cross checked with other information and should not be used as the sole means in making your purchasing decisions.