They are most commonly made from plastic or aluminum, and come in a variety of colors; with black and white bing the most widely available. In common with all such solar powered lights, they consist of a rechargeable battery (usually of the NiCad variety), a solar panel and several low power LED lights.
Since they require no wiring, installation is a simple matter of fixing the cap light to the top of the post with some screws, and should take no more than a few minutes to complete. Most lights are designed to fit standard 4″ x 4″ posts, though some come with adapters for smaller posts. It should be noted that the amount of light produced by most models is quite low – these lights are not intended to provide a lot of illumination, but are meant to provide decoration and serve as a useful marker.
Since solar powered post cap lights obviously require sunshine to recharge the battery, it’s important to locate them in an area where thet will receive a reasonable amount of sunlight. Positioning them in very shady areas is not a good idea.
Fortunately this type of lighting won’t break the bank, with models available for under $10. One thing to be aware of is that very cheap ones may not be completely weather-proof; if water enters the unit condensation may form, reducing the light’s efficiency.