Fence Solar Panel

Constantly charging or switching batteries is a headache that just adds more work to your already lengthy list of chores.

While buying a complete solar energizer can be expensive, it is cheap and easy to build your own. With the right solar panel connected to your fence energizer, you can match input with output and stop switching and charging your battery. This will decrease both the cost of your electricity and the amount of work it takes to maintain your fence, making electric fence as easy as a barbed wire fence.

Of course, you could go down to Peavey Mart and grab a cheap panel and end up fixing the thing as much as you charged your batteries. 

Or, you could keep reading and see exactly what you need to make sure your fence works with minimal effort.

Getting the right solar panel

Making sure you have the right solar panel for your fence and your sun conditions is going to take a little bit of math. But don’t worry. Even if you hate math, this will be straightforward. 

And, we’ll be right here, walking through each calculation to make finding the right energizer simple.

3 steps to finding the right energizer for your needs

Step 1: Calculate the amp hour (Ah) needed per day 

First, you need to understand the amp requirements for your fence. 

To do that, determine the wattage of the unit by multiplying the battery voltage, typically 12 Volts, by the energizer amps. 

Then, calculate how many watts hours you need by multiplying the wattage (or watt hours) you found in the last calculation by 24 (the amount of hours in a day). 

Now that you know your wattage (or watt hours), divide that by 12 (which is based on the voltage of the system, i.e. 12V) to get the amp hours.

Sounds confusing? Let’s take a closer look at this in action to make it easier.


Battery voltage x Energizer amps = Watts

12v x .29A = 3.48W

Watt hours = 3.48W x 24 hours = 83.52Wh

Determine Amperage Hours

A= W/V

Ah = 83.52WHr/12V = 6.96 Ah per day

Step 2: Determine peak sun hours for your location.

There are a lot of measurements of sunlight you can use, but different measurements require different calculations. We like to use peak sun hours, which we can help you find for your specific area, or you can look online.

For our example, we’ll take the average peak sun hours for Alberta, which is 3.3 hours.

Step 3: Calculate which solar panel will provide the Ah per day you need.

Now we’re finally getting somewhere. By dividing the amp hours you need (taken from the calculation in step 1) by the number of peak sun hours per day in your area, you can find the amperage you need. Then, it’s a fairly simple calculation to turn those amp numbers into watts to find the right solar panel for your system and your area.


6.96Ah (from step one) / 3.3Hr (from step two) = 2.109A

So, that means for this example you want a panel that produces 2.1A. 

From there, you can determine the wattage of the panel you need with a simple calculation.

Watt = Volt x Amps

? = 12V system x 2.1A we just found we needed.

That means you need a 25.2 watt panel 

These numbers are averages, which means you’ll have better and worse days. So, we recommend you always add 20% to your calculation to take into account the real-world conditions on your property.

20% of 25.2 is 5.04

25.2 + 5.04 = 30.24 Watt Panel, which you can round to a 30 watt panel.

*A note on batteries

All of these calculations depend on a battery that will take multiple charges over years without significant degradation. That’s why we recommend deep cycle batteries for solar-powered fence systems. Deep cycle batteries are designed to discharge over a longer period of time (up to 100 hrs) than regular car batteries and can be recharged hundreds and even thousands of times over their life cycle. 

If you really want to maximize battery life, avoid discharging your batteries beyond 40-50% of their capacity. When doing calculations take this into account so that you’re not constantly replacing batteries.