Outdoor solar lighting systems use solar cells, which convert sunlight into electricity. The electricity is stored in batteries for use at night. Manufacturers most commonly use nickel cadmium, sealed lead acid, and lead acid batteries.
Outdoor solar lighting systems will work in most areas of the United States. However, it is important to consider geographic and site specific variables when choosing a product. A solar lighting system will work well only as long as the solar cells receive the manufacturer's recommended hours of sunlight.
The "nightly run time" listings on most "off-the-shelf" products are based on specific sunlight conditions. Outdoor solar lights located in places that receive less sunlight than the solar cells need will operate for fewer hours per night than expected. Nightly run times may also vary depending on how clear the sky is on any given day. Operating times in the winter months may vary as much as 30%–50%. Unless the solar lighting system has been sized specifically for winter operation, it will not operate for the specified number of hours per night in a given location. Shading of the solar cells by landscape features (vegetation, buildings, etc) will also impact battery charging and performance. Watch for bird droppings, too. Insufficient battery charging will not only affect performance, it also may reduce the life of the battery.
Some solar lighting systems are self-contained units. You only need to place the lights in a sunny location. Others have the lights separate from a solar cell panel. Only the panel needs to be placed in a sunny location. Units vary in size from small eight-inch, red-glowing pathway markers to pole-mounted patio and high-beam security lights.
Before you buy an outdoor solar lighting system, check with the manufacturer to see if replacement bulbs or batteries are available. Some units do not provide replacement options.
Home outdoor solar lighting systems are often available in hardware, lighting, and discount stores as well as through environmentally oriented mail order companies.