An electric fence energiser is one of the jobs solar is best at. It sends a short pulse down the wire about once a second and uses very little energy in between, so a small panel and battery keep it running in a paddock miles from a socket. The things that decide whether your fence actually works are the energiser's output, the length and condition of the fence, and - more often than anything else - the earth.
How a solar fence energiser works
A solar energiser is a normal battery energiser with a panel on top. The panel charges a battery during the day, and the battery runs the energiser day and night. Some are all-in-one units with the panel, battery and energiser in a single box you stake into the ground. Others are a 12V energiser that you connect to a separate leisure battery, with a solar panel kit to keep that battery charged.
Joules, distance and which animals
Two numbers matter on the box. Output energy in joules decides how hard the shock is and how well the fence copes with grass touching the wire. Rated distance tells you how much fence it can power, but it is measured on a clean single wire, so treat it as a best case - long grass, several strands and poor insulators all cut real-world range sharply.
| Use | Typical need | Solar fit |
|---|---|---|
| Strip grazing a horse paddock | Short fence, low to moderate output | All-in-one unit |
| Several horse paddocks | Longer fence, more output | 12V energiser, battery and panel |
| Sheep netting | Higher output, lots of vegetation contact | 12V system, sized generously |
| Large cattle or mixed farm fencing | High output, long distances | Mains energiser if power is available |
Manufacturers usually recommend a minimum voltage on the fence for each type of animal, and it is higher for sheep, whose wool insulates them, than for horses or cattle. A fence tester costs about £15 and is the only way to know what your fence is actually delivering.
What about a UK winter?
Energisers use little power, but they run 24 hours a day, including through long December nights. That is the one situation where a small built-in panel can struggle, particularly with a long or overgrown fence drawing more current. If your animals are out all winter, choose a unit with day/night mode, which slows the pulse or lowers the output when it is dark to save battery, or use the 12V route below with a bigger battery. Keep the panel clean and pointing south.
All-in-one or a DIY 12V system?
| All-in-one solar energiser | 12V energiser + battery + panel | |
|---|---|---|
| Cost | ~£140 | ~£140 |
| Output | 0.25J (example) | 0.6J (example) |
| Rated distance | 5km | 10km |
| Setup | Stake it in and connect | Connect three parts |
| Winter reserve | Small built-in battery | 50Ah leisure battery |
| Moving it | Easy, one unit | Heavier, three parts |
For about the same money, the DIY route gives you more than twice the output and a battery with far more winter reserve. The all-in-one unit is simpler and easier to move between paddocks. If you only strip-graze one or two horses, buy the all-in-one. For anything bigger, build the 12V system.
The earth, where most faults are
An electric fence completes its circuit through the ground, so a poor earth means a weak shock however good the energiser. Most "my energiser is not working" problems are earth problems. Use at least one proper earth stake, drive it deep into ground that stays damp, and add more stakes in dry summers or sandy soil. Check insulators for cracks, and keep grass away from the bottom wire, because every blade touching it drains power.
Safety and footpaths: electric fences next to public rights of way should carry yellow warning signs at regular intervals. Never connect an energiser to barbed wire, and never use a mains energiser that has not been designed for fencing.
Recommended kit
Everything below was in stock on Amazon UK when this guide was written.
My Animal Command solar electric fence energiser
A self-contained solar energiser that stakes into the ground, suited to strip grazing and one or two paddocks for horses or ponies. It is the most-reviewed solar energiser on Amazon UK, rated 4.5 stars from 673 ratings.
amazon Check Price on Amazon →XSTOP BA80 12V battery energiser
More than twice the output of the all-in-one for well under half the price, because you supply the battery and panel. Rated 4.0 stars from over 2,100 reviews. Pair it with the panel kit and battery below.
amazon Check Price on Amazon →Topsolar 20W solar panel kit with 10A controller
A 20W panel with a charge controller is plenty to keep a leisure battery topped up for an energiser drawing a few watts. Rated 4.4 stars from over 3,600 reviews.
amazon Check Price on Amazon →SuperBatt LM50 12V 50Ah leisure battery
The battery that keeps the fence live through a grey week. Deep-cycle leisure batteries cope with being drained and recharged every day, which a car battery does not. Rated 4.4 stars from 95 reviews.
amazon Check Price on Amazon →Rutland fence voltage tester
The only way to know what your fence is actually delivering, and the fastest way to find a short. Rated 4.5 stars from 240 reviews.
amazon Check Price on Amazon →Summary
- Energisers are an ideal solar load - small, steady and needed where there is no mains
- Treat the rated distance as a clean single-wire best case
- All-in-one units suit strip grazing and small paddocks; a 12V system suits anything bigger
- For the same ~£140, the DIY route gives more output and more winter reserve
- Most faults are earth faults - use deep stakes and a fence tester
- Put warning signs on fences next to public footpaths
If you keep horses, our guides to solar power for stables and tack rooms and horsebox solar panels cover lighting, cameras and charging at the yard and on the road.
Frequently Asked Questions
Do solar electric fence energisers work in winter?
Yes, but winter is the hardest time because the energiser runs through long nights while the panel gets little light. Choose a unit with a day/night mode, keep the fence clear of grass, or use a 12V setup with a larger leisure battery.
How far will a solar energiser power a fence?
The rated distance is a best case on a clean single wire. Several strands, long grass and poor insulators cut it sharply. Buy an energiser rated well beyond your actual fence length.
Is a solar energiser strong enough for horses?
For strip grazing and typical paddocks, yes. Horses respect a fence well once trained. Use a fence tester to check the voltage along the whole fence, not just next to the energiser.
Can I use a car battery for an electric fence?
It will work for a while, but car batteries are not designed to be drained and recharged every day and wear out quickly. A deep-cycle leisure battery lasts much longer.
Why is my electric fence weak?
Usually the earth. Drive earth stakes deeper into damp ground, add more stakes, and check for grass touching the wire and cracked insulators.