The simplest system And the cheapest Solar Rooftop for residential homes. is to generate electricity during the day and use it immediately, called On Grid. Home lighting system, which is the simplest system. And the cheapest of Solar Rooftop, this system is suitable for daytime use only. But if you want to use Keep a backup for use during the night as well. Battery must be used in conjunction with it, called Hybrid, which will have a higher price than On-Grid.