Why solar is the default for remote cameras
Some of the best camera positions have no power outlet nearby: the front gate, the back fence, a barn, a shop shutter, a construction site. Running a cable to one of those spots often costs more than the camera itself, and landlords do not always allow drilling. A modest solar panel plus a battery keeps a camera running through the night and through cloudy spells, with no electrician bill.
Camera makers love to advertise "solar powered" bundles, but the included 5-watt panel usually assumes the camera sleeps most of the day and wakes only for short motion clips. A camera that records or streams around the clock burns far more. Under-size either the panel or the battery and the camera goes dark at 3 a.m. — usually on the one night you needed it. The sizing is simple arithmetic, and it rewards honesty.
How much power different cameras use
Everything starts with watts, and camera power draw varies more than most people expect:
| Camera type | Typical average draw | What it means in practice |
|---|---|---|
| Battery Wi-Fi camera | ~0.5 W | Sips power, wakes on motion, deep-sleeps between events |
| PoE / wired IP camera | ~6 W | Runs all day and night; infrared LEDs at night draw extra |
| PTZ camera | ~12 W | Pan, tilt and zoom motors push consumption up, especially on windy days |
If the camera's manual lists a wattage, use that number instead of the averages. A camera that records in 4K with its spotlight on every night can sit noticeably above the typical figures.
Step 1: Work out the daily energy
Daily energy is the foundation of every solar camera system: cameras multiplied by watts multiplied by 24 hours.
Daily energy (watt-hours) = number of cameras × watts per camera × 24
For example, two PoE cameras at 6 W each need 2 × 6 × 24 = 288 watt-hours per day. Everything that follows — panel size and battery size — is built on this one number, so measure it carefully rather than guessing.
Step 2: Size the panel
The panel must harvest the daily energy inside the available sunshine. Divide the daily watt-hours by peak sun hours, then divide again by 0.75 — a real-world derating that accounts for heat, dust, wiring losses and controller efficiency. A panel rarely delivers its nameplate rating, so this factor is not pessimism; it is engineering.
Panel watts = daily watt-hours ÷ (peak sun hours × 0.75)
Taking the 288 Wh example with 5 peak sun hours: 288 ÷ (5 × 0.75) = 76.8 W. Round up to the nearest standard panel size — 100 W. Rounding up is deliberate: an extra twenty watts of panel is far cheaper than replacing a camera system that dies every winter.
Step 3: Size the battery for cloudy days
The battery does the night shift and stretches the system through sunless days. Multiply the daily energy by the number of cloudy-day backup days you want, then divide by battery voltage times the safe depth of discharge. A lead-acid battery should only be drained to about 50% to stay alive; a lithium (LiFePO4) battery can safely use about 80% of its capacity.
Battery Ah = (daily watt-hours × backup days) ÷ (12 V × 0.5 for lead-acid)
With the 288 Wh example and two backup days: 288 × 2 ÷ (12 × 0.5) = 96 Ah of 12 V lead-acid battery. Switch to lithium, which tolerates 80% depth of discharge, and the same backup needs roughly 60 Ah — pricier per unit, but it survives about three times as many charge cycles. Two backup days is the standard starting point; regions with long overcast spells should size for three or four days and keep the panel oversized so the battery refills fully on the first sunny day.
Two worked examples
Example one, light load: four battery-style Wi-Fi cameras at 0.5 W average, in a location with 4 peak sun hours, sized for 3 cloudy days. Daily energy: 4 × 0.5 × 24 = 48 Wh. Panel: 48 ÷ (4 × 0.75) = 16 W, so round up to a 20 W panel. Battery: 48 × 3 ÷ (12 × 0.5) = 24 Ah, so a single 12 V 30 Ah battery covers it comfortably. The complete kit — one 20 W panel, one small battery, one charge controller — is genuinely pocket-sized.
Example two, heavy load: three PTZ cameras at 12 W each, 4.5 peak sun hours, 2 cloudy-day backup. Daily energy: 3 × 12 × 24 = 864 Wh. Panel: 864 ÷ (4.5 × 0.75) = 256 W, so a 300 W panel after rounding up. Battery: 864 × 2 ÷ (12 × 0.5) = 288 Ah of lead-acid, or about 180 Ah of lithium. Notice how the same formulas scale from a garden camera to a full perimeter system without changing.
Installation tips that make or break the system
- Point the panel toward the equator — south in the northern hemisphere — and tilt it to roughly your latitude for the best year-round harvest. A steeper tilt also sheds snow and dust.
- Oversize the panel by about 20% if the site is dusty or the panel sits behind glass, which steals a surprising amount of light.
- Always use a proper solar charge controller. Connecting a panel straight to a battery will overcharge and destroy it within months.
- Size for winter, not summer. December sun hours can be half of June's, and that is exactly when the camera matters most.
- Keep the panel out of partial shade. Even a small shadowed strip from a branch or antenna can cut a panel's output far more than the shaded area suggests.
- Mount the battery in a weatherproof box off the ground, somewhere it stays cool in summer and above freezing in winter — cold batteries hold noticeably less charge.
Common sizing mistakes
- Trusting the bundled panel. A 5 W panel works for motion-sleep cameras, not for 24/7 recording. Size from your real duty cycle.
- Forgetting the night-time infrared load. IR LEDs add real watts all night long; measure total draw, not just the daytime figure.
- Sizing from summer sun hours. Use the worst month's peak sun hours, or the system that works in July dies in January.
- One backup day. A single cloudy day is normal; two in a row is common. Plan for two days minimum, more in gloomy climates.
- Skipping the charge controller. Panels without regulation kill batteries — and a dead battery looks exactly like a dead camera.
Try it now: Security Camera Solar Sizing Calculator — size the solar panel and battery your cameras need from your camera count, local sun hours, and backup days.
Frequently asked questions
What size solar panel do I need for a security camera?
For a typical PoE camera drawing about 6 W, budget roughly 80–100 W of panel with 5 peak sun hours. A low-power battery camera drawing about 0.5 W can run on a 20 W panel. The exact figure depends on camera count, wattage, and local sun hours, so run your numbers through the sizing formulas above.
Can a solar panel power my security camera at night?
Not directly — at night the battery does the work. The panel charges the battery during the day; the battery Ah figure in your result is what keeps the camera running after dark. Size the battery for at least two cloudy days of backup.
How many cloudy days of backup should I plan for?
Two days is the standard starting point for most climates. In regions with long overcast spells, size for three or four days, and oversize the panel so the battery recharges fully on the first sunny day.