Solar outdoor and security lighting

A typical inexpensive solar path or motion light has a 1–5 W panel, a small nickel-metal-hydride or lithium cell, and no charge management to speak of. In June it works: fifteen hours of daylight fills the cell and the light runs all night. In December, Denver gets a little over nine hours of daylight, the sun is low, the panel is often flat or pointing at the house, and a dusting of snow ends the day’s charging entirely. The cell gets shallower every day until the light flickers on for an hour and quits.

Cold finishes the job. Nickel-metal-hydride cells lose capacity as temperatures drop, and the lithium cells in better lights should not be charged below freezing, which a light mounted on a north wall in January never rises above. Add UV that yellows the plastic lens and the panel cover within two or three Colorado summers, and the two-year lifespan most people report is the physics, not bad luck.

The lights that last share a few traits. A separate panel on a cable, so the panel goes on a south-facing tilt in the sun while the light goes where it’s needed. A lithium iron phosphate battery with a rated low-temperature cutoff, or at least a battery large enough to carry two or three dark days. Motion-only operation rather than dusk-to-dawn, which cuts the nightly energy budget by a factor of ten. And a glass panel face and a metal housing rather than plastic. Rough market prices for lights in this class run $60–$300 apiece; prices vary.

Mount the panel above the snow line and at a steep tilt — 50–60 degrees faces the low winter sun and sheds snow — and give it a clear view south. For pathway lighting, accept that solar path lights are a summer amenity in Colorado and plan for them to dim in winter, or go low-voltage hardwired, which is the next section.

If your house already has rooftop solar, the simplest reliable outdoor lighting is a 12-volt landscape transformer (100–300 W is typical) plugged into an exterior outlet, running LED path and accent fixtures on buried low-voltage cable. Motion-sensing LED security floods at 20–50 W wire to a standard exterior box. None of it needs a permit beyond what the exterior outlet required, and none of it has a tiny battery to freeze.

The energy is small enough that the rooftop array barely notices. A 30 W flood on dusk-to-dawn runs roughly 4,000 hours a year, about 130 kWh, which is less than a tenth of what a single residential panel produces annually in Colorado. A landscape transformer with a dozen LED fixtures on a timer is in the same range. When we size a system we work from your annual usage, so if you plan to add outdoor lighting, tell us and we’ll include it.

The situation that genuinely favors standalone solar lighting is distance: a barn 400 feet from the house, a gate at the county road, a driveway with no power anywhere near it. Low-voltage landscape wire loses too much over that run and trenching a 120-volt line costs real money — often into the thousands over a few hundred feet, depending on soil, rock, and the electrician. A standalone solar area light with a 20–60 W panel, a proper battery box, and a motion sensor solves the barn-door problem without a trench, at rough market prices of a few hundred dollars per fixture; prices vary.

If the outbuilding is going to get power anyway — for a shop, a well, a gate opener, or cameras — the trench is the better long-term buy and the lighting rides along for free. Many rural Colorado counties and several towns are certified dark-sky communities or have outdoor-lighting codes, so choose shielded, downward-facing, warm-color fixtures on motion sensors regardless of how they’re powered; your neighbors and the local elk will both notice.

Hardwired lights go dark when the grid does, and a grid-tied solar array without a battery goes dark with it. Standalone solar lights keep working through an outage, which is a modest point in their favor for a mountain home during a wildfire shutoff. A permanent home battery keeps the exterior circuits on as well, along with the well pump and the refrigerator, which is why customers in shutoff areas usually end up there rather than with a yard full of small solar fixtures.

We install grid-tied rooftop and ground-mount solar, batteries, and EV chargers on Colorado homes; we don’t sell or mount solar lights, and we don’t run landscape wiring. What we can do is size a system that covers your outdoor lighting and, with a battery, keeps it lit when the power is out.