Here are some neat projects for your study, free learning material. Solar Oven Cooker, Anemometer Circuit, Simple Data Logger.
Highlights are How to Measure the Power Output of Solar Panels and the Time Controlled Relay Switching Kit.
They also sell a Battery Amp Hour Meter and a Crystal Diode set which contains 1N34A diodes, 1N60 and D9B for learning electronics. They are Germanium Diodes.
An interesting Energy solution is the Hand Cranked DC Generator Plans. It describes how to build a hand operated electric power generator using a standard DC gearhead motor.
Solar Tracker Circuit Kits helps you servo position your Solar Cell Array, you can build a device which will automatically follow the sun across the sky.