Solar Electric Fencing

One of the biggest problems facing users of electric fencing is that the power unit (the energiser) is often a long way from a mains power supply. As a result, users have to rely on heavy 12V deep cycle batteries which have to be moved once every few weeks to be charged. Given that a typical battery can weight between 15 and 30kg, carrying one across a field is not a great prospect.

As a result, more and more people are incorporating solar panels into their fence systems, generating a local source of energy and eliminating the need to recharge the batteries. Some modern fence units are factory fitted with a small solar panel, but they are easy to retrofit to an existing fence system:

First calculate the amount of power that the fence energiser consumes in a day, by multiplying the current draw (in amps or milli-amps) by 24 and then multiplying that by 12 to get the power consumption in watt-hours (Wh). To ensure that the solar panel produces enough energy all year round, we use a calculation of 70% energy production for 5-hours a day. Starting with your 'Wh' number, divide this by 0.7 and then divide the result by 5. The result will be the minimum solar panel size you need.

To help with calculating the size of the solar panel needed for your electric fence system, you can use the tables at the bottom of this page, or use our new Electric Fencing Solar Panel Size Calculator

Each solar panel has a specification called the 'short circuit current' given in amps (A). If this number is less than 2% of the capacity of your battery (amp hours / Ah) then you do not need a charge controller. If it is more than 2% you should ideally use a charge controller between the battery and the solar panel, or get a bigger battery.