Solar Powered Electric Fences

Electric fencing can be a cost effective and practical method of fencing for a wide variety of animals.

There are several brands and models available from rural agricultural stores which are battery powered as opposed to being powered by the 230V grid. The battery type units can then be powered by solar modules.

Due to the wide selection of energisers and accessories on the market, we no longer sell the energisers. However, we can supply you with a suitable solar panel and battery.

When you buy the energiser, only buy one as big as you require, e.g., if a 3 km unit will do the job, don't purchase one for 20 km, as they will need a solar panel several times larger and more expensive than you'd otherwise require. A 3 km energiser can be typically powered by a 2-5W solar module.

Several months ago one of our readers, Jules, submitted some hints about using electric fences which is reproduced below:

"I have used a number of different electric fence units, from small to medium large, to power up to several kilometres of fence, and I believe that they are an almost essential part of fencing. In theory, smaller units are fine for shorter fences, but in practice, shorting out from long grass/plants is an unavoidable drain in most situations. Medium and large units are available using 12V power and either an attached solar panel or a separate panel. The units with a built in solar panel are rather costly for what you get and the logical conclusion might be to run your fence off your 12V home battery bank/solar system. Provided all the connections are good, and the unit is operating properly, this causes no more trouble than a pulse across your TV screen with each fence discharge. There are however two major problems that inevitably crop up over a longer (several year) period:

a) As mentioned in your book (Energy From Nature), lightning is a hazard to electric fence units. Even if you do not have any direct strikes of lightning, a farm fence is a custom designed electricity catcher. It is of course possible to use diverters to earth (most) of a lightning strike and it is sometimes possible to detach a fence during a storm (though this could be dangerous in itself). The problem with lightning is that the voltages generated are just so huge that any form of protection has its limits.

b) Electric fence units are subject to more failure than most other electrical equipment. I'm not sure why this is, but I'd guess that the mixture of low voltage with strong pulses of high voltage is problematic. It is quite common to get some sort of feedback of high voltage from the output side of the circuit to the input. Some units seem to do this when in perfect working order and others can develop it as a fault where transformer insulation breaks down.

Both of the above failures can be very serious for sensitive electronic equipment like computers and solar regulators. The best and safest way to power an electric fence is from a separate panel/battery/earth system preferably housed in a shed away from your house. A reasonably cheap and very functional system can be put together with a second hand solar panel (and if you've been using solar for a while you might well have a spare), a decent car battery (or that size of deep cycle battery), and the highest output 12V fence unit you can stretch to."