If the solar lights you have around your garden or home are dim or dark, it may be that the plastic panel over the light’s collector has weathered and now the sun’s rays can’t reach it to fully charge them. A quick fix is, using an all-purpose cleaner, to remove any dirt and then dry. A longer term solution is to spray with a UV resistant clear spray paint such as Rust-Oleum American Accents Ultra Cover 2X Gloss Clear. This will fill in any scratches and pits in the plastic to get the lights shinning again.