The load controller is discussed in more detail in Chapter 12. It optimizes and conforms to the transfer of photovoltaic energy generated by the modules in order to match consumption needs. It also protects the battery against excessive overcharging and overdischarging.
Banks of batteries accumulate the electric power generated during the day, making it available whenever necessary. They usually consist of lead-acid deep-cycle batteries, preferably sealed and possibly with no need of water replacement (although those batteries are more expensive), with a nominal voltage rated at the dc-link voltage. Further details of battery banks, maintenance, and sizing are provided in Chapter 11. A battery bank also requires a healthy monitoring system to indicate the state of charge and to support the maintenance.