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☀️ Calculate Your Solar Panel & Battery Size
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Solar Panel Calculator for Fence Energizers
Choosing the right solar panel for your electric fence energizer is critical to keeping your fence powered, especially in remote areas without access to grid electricity. As a general rule, you’ll need about 10 watts of solar panel power for every output joule of your energizer. For example, a 3-joule energizer typically needs a 30-watt solar panel.
Use the steps below to calculate the right panel size based on your energizer, battery, and location.
Step 1: Calculate the Amp-Hours (Ah) You Need Per Day
Start by finding out how much power your energizer consumes.
Formula:
Watts = Voltage × Amps
Watt-hours = Watts × 24 hours
Amp-hours = Watt-hours ÷ Battery Voltage
Example:
- Voltage: 12V
- Current: 0.29A
- Watts = 12V × 0.29A = 3.48W
- Watt-hours = 3.48W × 24h = 83.52Wh
- Amp-hours = 83.52Wh ÷ 12V = 6.96 Ah per day
This means the energizer will use approximately 6.96 amp-hours of energy from the battery each day.
Step 2: Find the Peak Sunlight Hours for Your Area
Peak sunlight hours vary by location and season. These are the average hours per day when sunlight is strong enough to generate usable power.
Example:
Blairsville, PA receives approximately 3.68 peak sun hours per day.
Use your regional average to calculate the panel size needed.
Step 3: Calculate the Solar Panel Size Required
Now divide the amp-hours needed per day (from Step 1) by the average peak sun hours (from Step 2).
Formula:
Amps needed from panel = Ah needed ÷ Sun hours
Example:
6.96 Ah ÷ 3.68 hrs = 1.891 A
Next, determine the solar panel wattage needed to generate that amount of current.
Formula:
Watts = Volts × Amps
Example:
12V × 1.9A = 22.8W
Add 20% to compensate for real-world inefficiencies:
22.8W × 1.2 = 27.36W
Result: Round up to a 30-watt solar panel.
Battery Tips for Solar Fence Systems
Use a deep cycle battery for your solar-powered fence setup. These batteries are designed for long, steady discharges and frequent recharging — perfect for energizers.
Best Practices:
- Never discharge below 40–50% of the battery's rated capacity.
- A 3-joule energizer can operate for about 8.6 days without sunlight using only half the battery's capacity.
- For best results, pair your energizer with a properly sized solar panel and battery to ensure consistent performance.
What to Do With the Results
Once you know the panel wattage required, choose a solar panel that meets or exceeds that value. You should also match your system with a compatible battery rated to handle several days of backup operation. If needed, add a charge controller to avoid overcharging your battery.
Find the Right Solar Panel for Your Fence Energizer
Once you've calculated your daily energy needs, choosing the right solar panel becomes simple. This durable, polycrystalline panel is available in multiple wattage options to match energizers of different output sizes. Whether you're powering a small pasture or a multi-wire perimeter, you can select the panel size that fits your setup.
Pre-wired for easy installation and backed by a 5-year warranty, it’s built to perform in rugged farm environments. Match your energizer’s output to the appropriate panel size and power your fence reliably — even in remote areas.
Need Help Sizing Your Setup?
Have questions about your energizer, panel, or battery setup? Our team is happy to help you find the right products for your fence system.
Call us at 1-800-KENCOVE for fast, friendly service and expert advice.
