The technology behind solar landscape and outdoor spotlights is simple, but the main problem with these lights is that they are made from inexpensive materials. The working parts -- including the solar panel and light bulb -- may not be replaceable, and if they are, it's usually less troublesome to simply buy a whole new fixture. If you understand how the light works, though, you can easily fix minor problems.
How It Works
A solar landscape light is a miniature version of a photovoltaic system that supplies electricity for a building, but it lacks an inverter because there's no need to convert the output from the tiny panel to alternating current. Instead, the panel, which usually mounted on the top of the fixture, connects directly to a rechargeable battery, and it's the battery that powers the light-emitting-diode lamp. When the LED doesn't light, it's seldom the fault of the LED itself -- LEDs can last for 50,000 hours. It's usually that of the battery or panel.
Bring Back the Light
Solar lights, like conventional ones, have an on-off switch; it's usually located next to the battery compartment. Make sure this switch is on. If the fixture is new, remove the plastic tab from the battery compartment.
Most landscape lights take one or two rechargeable AA or AAA batteries. Precharge replacement batteries in a wall charger, then remove the old batteries and put in the charged ones.
If your lights have seen more than one season outdoors, the panels may be dirty or frosted over. Clean the panels with soap and water. You can often make frosted panels clear again by brushing them with clear nail polish. If the plastic is soluble in lacquer thinner or acetone -- as many plastics are -- the polish will emulsify it, and it will re-form into a clear, frost-free material. If the material isn't soluble, no harm done! The nail polish won't affect it, and you can clean it off with nail polish remover.
Solar lights need several hours of sunlight every day to recharge the batteries. If yours are in a shaded spot, move them to a spot with more sun.
If none of these strategies is successful, the battery connections may be loose or corroded. You can disassemble the fixture to resolder or replace these, but because solar lights are so inexpensive, it's seldom worth the trouble. If you decide to do it, use silver solder -- not plumber's solder -- to reconnect wires to the battery, panel and LED terminals.