Solar Cells and Rechargeable Batteries

Abstract

Electronics systems rely on power, and for most portable systems this will be provided by batteries, and quite often these will be rechargeable batteries. We can take portable power systems a step farther by using solar cells to provide the operating power or to recharge the batteries. Solar energy conversion is not all that efficient and can be affected by the sun’s position in the sky, shadows, and clouds; however, there is often plenty of light energy available for small solar cells used in charging small batteries, storage capacitors, or driving low-power systems. Recharging batteries is a complicated subject, and each manufacturer and type of battery can require different charging profiles, i.e., how the voltage and current are balanced over time.1 Most manufacturers provide very detailed information about how to optimally charge their batteries, and electronics manufacturers have responded with specific ICs that have been developed to provide the correct charging profiles. The variations in the needs of different types of batteries make it important that you check with the manufacturers of the specific components to ensure that the batteries are not damaged when recharged. This becomes particularly important when fast charging batteries. In this chapter we will be concentrating on the generation of electrical power using solar cells, and using this to charge batteries and provide power to other electronics devices and instruments.