Photo Voltaic Solar
Solar water heating systems almost always require a backup system for cloudy days and times of increased demand. Conventional storage water heaters usually provide backup and may already be part of the solar system package.
A backup system may also be part of the solar collector, such as rooftop tanks with thermosyphon systems. Since an integral-collector storage system already stores hot water in addition to collecting solar heat, it may be packaged with a demand (tankless or instantaneous) water heater for backup.
Installing a Solar PV System
The heart of a Solar PV system is the grid-interactive inverter. The inverter takes electrical power generated by solar cells, converts it from direct current(DC) to alternating current (AC), and supplies it for household electrical consumption. Excess power generated during the daytime hours is fed back into the utility power grid. When the amount of power generated by the solar panels is insufficient for the home's needs,the system draws needed energy from the utility power network (or from an optional battery bank.