A Hybrid power generator is a unit containing batteries and an inverter that can produce power at mains voltage. It would generally be connected to a diesel generator that is run for part of the day, with the hybrid supplying the load when the generator is not running.
The most efficient “load profile” for a hybrid power system leading to the largest cost-savings, is an asymmetric load; a fairly large load for a portion of the day, and a smaller load for the remainder of the day.
Essentially the cost savings are made by virtue of the fact that diesel generators are only between 20-30% efficient at converting fuel into electricity (the rest goes to heat, noise, frictional and electrical losses). So if you can double the load on generator, but only run it for half of the time, you have generated the same amount of electricity but you have halved the amount of ‘wasted’ fuel.
The inverter in the hybrid unit is the brain of the system and will monitor loads and control the generator. The system can also be monitored and controlled remotely via GSM/3G.