An Electric Fence with Solar

Electric fencing can be installed with basic hand tools and no prior fencing experience. And by adding a solar-powered fence energizer, you’ll make installation even simpler by eliminating the need for any grid connection. Not only that, using a fence energizer allowing you to put the unit where needed without any consideration for a grid connection. You won’t have to worry about the animals if the utility grid goes down. Solar-powered fencing may provide an attractive solution when compared with trying to install a fence energizer that runs on 120-volt alternating current (AC), especially for remote or very large fencing systems that suffer from a lack of utility outlets near the fence line.

The Basics

A properly installed electric fence won’t cause serious harm to animals (or people!) that happen to come in contact with the energized wires. While most electric fencing consists of only a few bare wires strung between some lightweight insulators, it’s an animal’s learned fear of the fence — not the strength of the wire — that keeps the animal contained.

You must use the correct wire spacing and fence design for the animals you’re trying to contain.Some electric fencing systems use wires that are woven into a brightly colored flat tape or rope. This type of electric fencing material makes it easier for animals to recognize what happens when they get too near and thus remember to steer clear. Larger animals, such as horses and cattle, may be more manageable when using wider electric fencing tape because it’s easier for them to see than bare wire.

One of the newest forms of electric fencing is electrified netting. This fencing material works to contain smaller animals — goats, chickens, turkeys, rabbits, and even cats and dogs — better than wider-spaced electric fence wire.

Solar Fence Energizers

Electric fencing requires an energizer to deliver pulsed charges to the conductor, usually at or less than one high-voltage pulse per second. Some units list their output in volts, while others use joules (the international unit of energy measurement).

The best measurement of an electric fence energizer is how many joules of energy it delivers per pulse. A joule equals 1 watt-second of power output, or, more precisely, the amount of work required to generate 1 watt of power for 1 second.

However, if you use multiple smaller energizers, any single failure would mean only one of the fenced areas would become non-energized. Remember that these ratings apply to the total length of wire used, not necessarily the length of the fence. So a 6-joule energizer that can energize 100 miles of fence wire would provide enough power for a 5-wire fence that’s 20 miles long (or a 4-wire fence that’s 25 miles long, and so on). A solar-powered energizer with an output of 0.5 to 1 joule should easily meet the needs of most small-scale homesteaders, providing enough power to energize miles of fence wire or enclose up to 50 acres of pasture.

Most self-contained solar energizers consist of a weatherproof enclosure with a small solar panel attached to the top on an adjustable mounting.

Solar energizers with a larger capacity may require a bigger solar panel and battery, mounted separately from the energizer. The flexibility of the separate battery and solar panel will be especially useful if you need to reposition the solar panel away from the shade of nearby trees or would like to mount the panel on a raised pole.

Fence energizers powered by an external 12-volt battery typically cost half the price of energizers with a smaller built-in battery and solar panel. A solar fence energizer has a low power drain on the battery because the output power is pulsed on and off, rather than remaining continuously energized. This cycling allows time for the power circuits to increase the 12-volt battery voltage to more than 5,000 volts, which is then discharged in short pulses. In addition, this pulsing effect provides more shock value to an animal in the form of multiple “stings,” rather than a single continuous discharge.

If you’re already using a grid-connected energizer, converting to solar power will be very easy. It will require replacing your 120-volt AC energizer with a self-contained solar energizer with its own battery and solar panel. Unlike your existing grid-connected energizer, your solar energizer can be located almost anywhere with ample sun.

Installation

If you plan to assemble your own custom system, make sure your fence energizer is designed for the voltage of the external battery you want to use. A sealed recreational vehicle (RV) or marine battery will provide many more days of operation during long periods of cloudy weather than a model with a smaller internal battery. Maintenance-free deep-cycle batteries are designed for continuous charge and discharge cycling. Car batteries have much thinner plates to reduce weight and aren’t designed for this constant cycling.

When selecting a solar panel to keep your energizer battery charged, make sure it’s rated for 12-volt charging. Typically, the nameplate will list a 21-volt DC open-circuit voltage and a 17-volt charging voltage. A solar panel rated at 6 to 10 watts should be able to maintain the battery for an energizer rated at 0.3 to 0.5 joule, while a solar panel rated at 12 to 20 watts should be able to maintain the battery for an energizer rated at 1 to 2 joules. Which you choose will ultimately depend on the size of your fenced area, your climate conditions, and your latitude.

Grounding

Anytime an animal comes in contact with an energized fence wire, they’re completing an electrical circuit. Unfortunately, one of the most neglected areas of electric fence installation is properly grounding the system.

The ground rod is typically a copper-clad steel rod driven into the earth next to the energizer. Grounding is a major part of the electrical path from the animal back to the energizer, and must be installed correctly, otherwise this electrical circuit won’t be complete. Fenced areas that stay slightly damp year-round may only require one ground rod, while very dry climates may require multiple ground rods (typically spaced at least 10 feet apart) to achieve adequate ground contact.

Testing and Maintenance          

After you’ve installed the fence, ground rods, and solar-powered fence energizer, and properly positioned the solar panel, it’s time to test. This task will be best performed using a high-voltage fence tester. As you walk along the fence line, check the output of each wire and note any section of wire that’s not energized or that has a low voltage level.

If any objects, tree branches, or tall weeds come in contact with an electrified fence, they can drain off voltage and significantly lower the shock value, or even short all the voltage to the ground. Walk your fence line regularly and keep all weeds and tall grass at least 5 feet away from either side of the fencing. You’ll also want to check around the solar panel to make sure that weeds or bushes haven’t grown tall enough to shade any part of it.

As with any electrically energized equipment, be sure to follow the manufacturer’s installation and safety instructions.  You can even attach new solar-powered electric fencing to existing wood or metal fencing using the proper insulators. With a reasonable level of maintenance, your solar-powered fencing system should provide many years of trouble-free performance.