In June 2010 we thought we'd look at a simple cheap solar-powered garden light to see if they are any use. They don't give out a huge amount of light and there is an embedded environmental and energy cost even if they don't need mains or batteries. We splashed out on two of these.

These are very simple and cheap and physically small and light, possibly using a supercapacitor inside rather than a battery, powering a single cool-white LED pointing out the base of the unit through a clear plastic prismatic diffuser. The light given out is fairly weak but pleasant accent lighting; it wouldn't much help, for example, with navigating the garden at night.

Each unit consists of a small 'amorphous' brownish solar cell on top, a black plastic body with a thin metal covering sheet, and a removable diffuser and spike for planting in the earth. Under the diffuser/spike is a switch to turn the light off, thus presumably saving its juice for another day or if packed away.

My 19-month old boy managed to disassemble and break one unit fairly easily requiring the LED's leads to be resoldered to the board, but all-in-all the unit seems robust for normal uses!

These could be nicely adapted to make solar-powered lights for a doll's house, or for children's night-lights with some extension of the LED leads (one seems to last about 4 hours when fully charged).

All were dead after a year.

(More photos.)