Access control is a burst load on a site with bad sun exposure. A sliding gate motor can pull 5-15 A for a few seconds, then sit idle for hours; the panel meanwhile is mounted on a wall that is shaded by the very building the gate protects. Sizing this correctly means working from surge current and daily cycle count, not from a nameplate watt figure.
Load profile of a gate or barrier
| Equipment | Behaviour | Design implication |
|---|---|---|
| Gate motor (sliding or swing) | 5-15 A surge for 2-10 s, several times a day | Battery must carry surge; panel only replenishes energy |
| Barrier arm | 3-8 A surge, frequent cycles | Higher cycle count than a gate, lower energy per cycle |
| Controller / keypad / reader | 0.1-0.5 A continuous | Dominant continuous load over 24 h |
| Intercom with camera | 2-5 W continuous | Often forgotten in the budget |
| Safety sensors and beacons | Small but constant | Adds up, and cannot be cycled off |
A residential sliding gate with 20 cycles a day typically lands around 120-300 Wh/day including the controller and intercom — modest, but with a surge that a small gel battery cannot deliver without voltage collapse.
Why gates fail on solar
- Undersized battery for surge: the pack has enough Wh but too little discharge current, so the motor stalls and the controller browns out
- Panel in permanent shade: a panel on a north-facing wall under a tree produces almost nothing; the design fails regardless of size
- No low-voltage disconnect: the motor keeps trying until the battery is flat, then the site is dead for days
- Cable too thin: voltage drop on a long run from battery to motor causes spurious faults
Siting the panel
The single most common design error is placing the panel where the gate is, not where the sun is. Options, in order of preference:
- Panel on a pole or roof with clear southern (or northern) exposure, cable routed to the gate control box
- Panel on a separate small mast beside the gate, above the shade line
- Panel on the gate structure itself, accepting reduced yield and adding array margin
Keep the cable run from panel to controller as short as practical, and use a larger cross-section if it exceeds 10 metres — the voltage drop on a 12 V system is punishing.
Battery choice
LiFePO4 is the better default here: high continuous discharge for the motor surge, flat voltage under load, and no need to ventilate an enclosure the way flooded lead-acid does. Size on two numbers: usable energy for the cloudy-day run, and continuous discharge rating at least three times the motor’s running current.
Design checklist
- Measure actual motor current, including inrush, with a clamp meter
- Count daily cycles and add the continuous loads
- Choose battery on surge rating, not only watt-hours
- Add low-voltage disconnect set above the controller’s minimum
- Verify sun exposure at the panel position in winter, not summer
- Fit a manual release so the gate works when the battery is flat
FAQ
How big a solar panel do I need for an electric gate?
For a typical residential gate at 150-300 Wh/day, a 100-200 Wp panel with a 1-3 day autonomy battery is common. The battery’s discharge rating matters more than the panel wattage.
Can I run a gate motor directly from a solar panel?
No. The motor needs a current source that can deliver a surge on demand, which is the battery. The panel only replaces the energy used.
Why does my gate stop working in winter?
Shorter days, lower sun angle and panel shading from buildings or trees combine to cut harvest. A winter check of the actual panel position usually explains it.
Send us your motor model, cycle count and a photo of the panel position. Request a sizing proposal, or see solar power for security systems.