Batwatch is a simple monitor for a solar panel battery charger, using an Atmel ATtiny13V.
http://www.xs4all.nl/~dicks/avr/batwatch/index.html
Some working notes about the use of a microchip PIC 16F676 to analyse and measure the effectiveness of the garden solar light.
http://www.dougrice.plus.com/rt004/sr3/Logger.html
The idea is simple, the solar panel converts sunlight into a trickle of electricity. The electricity is used to run a white LED. It would make for an excellent science fair project, and would also serve as a good introduction to solar powered circuitry. It may also have some practical uses, such as shedding some light into a dark part of your house.
http://www.solorb.com/elect/solarcirc/pv2led1/index.html
It regulates the power flowing from a photovoltaic panel into a rechargeable battery.
http://www.solorb.com/elect/solarcirc/scc3/index.html
This almost trivial circuit may be used to charge a pair of AA or AAA sized rechargeable battery cells from sunlight. The circuit has been used to keep a Palm Pilot and walkman radio running perpetually. This is an unregulated charger, proper charging is achieved by placing the unit in the sun for a known amount of time, this time varies according to the battery type.
http://www.solorb.com/elect/solarcirc/aacharge/index.html
Tired of always spending money on flashlight batteries only to have them fail just when you need them? Try this simple circuit out. The white LEDs are quite bright, they provide enough light to illuminate a small room at night.
http://www.solorb.com/elect/solarcirc/solarfl/index.html
The goal of this project was to produce a self contained reading lamp that could be used by students in developing countries for reading at night.
http://www.solorb.com/elect/solarcirc/srl1/index.html
This contains a photovoltaic charge controller and a low voltage load disconnect circuit. It can be used to handle all of the power functions for small 12 Volt solar powered devices.
http://www.solorb.com/elect/solarcirc/spc2/index.html