Ranging from a simple mechanical generator , to complete electrical systems using renewable sources, such as solar or wind energy, to supply power to your home. The basic backup power system is a fossil fueled generator. They are relatively reliable, inexpensive and simple to install. Mechanical generators are acceptable for occasional emergency use, but as a long term solution efficiency becomes an issue. More sophisticated backup power systems incorporate a DC to AC inverter .
Inverters are preferable to mechanical generators in many respects.
They are extremely efficient. They are available in a variety of sizes, from small compact units tailored to the demand of a single load to large powerful models to supply the electrical needs of an entire household. The inverter, in and unto itself, is not a complete system. A charging source. In utility connected systems the inverter operates as a backup to the utility supply.