Security Camera Solar Sizing Calculator

Why solar makes sense for security cameras

Some of the best camera spots have no power outlet: the gate, the back fence, the barn, the shop shutter. Running cable there costs more than the camera itself, so solar kits have become the default answer. A small panel plus a battery keeps a camera running through nights and cloudy days, and the sizing is simple arithmetic — match the panel to the daily energy the camera burns, and match the battery to how many sunless days you want to survive.

The catch is honesty about the numbers. Camera makers advertise "solar powered" but their bundled 5-watt panels assume short clips and motion sleep. A camera recording or streaming 24/7 needs a panel several times bigger. Under-size either half and the camera goes dark at 3 a.m. — usually the night you needed it.

How the sizing math works

First, daily energy: cameras × watts per camera × 24 hours. A PoE camera draws about 6 W around the clock, so two of them need 288 watt-hours per day. Then the panel: divide daily watt-hours by (peak sun hours × 0.75). The 0.75 accounts for real-world losses — heat, dust, controller efficiency. With 5 sun hours, those two cameras need 76.8 W of panel, and you round up to the nearest standard size: 100 W.

Battery sizing is the autonomy math: daily watt-hours × backup days, divided by (12 volts × 0.5 depth of discharge for lead-acid). Two backup days for our example means 96 Ah of 12 V battery. A lithium (LiFePO4) battery can safely use about 80% of its capacity, so you could drop that to around 60 Ah — more expensive per unit, but it lasts roughly three times longer.

Worked example

Four battery-style Wi-Fi cameras, each sipping 0.5 W on average, in a place 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 → round up to a 20 W panel. Battery: 48 × 3 ÷ (12 × 0.5) = 24 Ah — a single 12 V 30 Ah battery covers it comfortably. Total kit: one 20 W panel, one small battery, one charge controller — a genuinely pocket-sized setup.

Practical tips

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 gets dusty or the panel sits behind glass. Always use a proper solar charge controller — connecting a panel straight to a battery will overcharge and kill it. And size for winter, not summer: December sun hours can be half of June's, and that's when the camera matters most.