These systems generally consist of a battery bank, a charge controller, a PV array, an inverter if the required output is AC, and sometimes, a tertiary power source such as a wind turbine or a gas generator. It is fairly complex and requires a high level of expertise to design and install these systems.
When your off-grid solar power system produces excess electricity during the day, it is used to charge the batteries. When the sun’s not shining, electricity is drawn from the batteries to power the home or business. The advantage is greater independence for you. The disadvantage is greater complexity and cost. And there is no backup power if weather doesn’t allow the panels to charge the batteries.
Off-grid systems are the only way to go if you live in a remote area where there are no utilities. They may also be appropriate where the grid is somewhat close to the site, but expensive to bring in. But, if you have the ability to connect to the grid easily, why wouldn’t you? First and foremost is the idea of independence from utilities. No more worries about rate increases. If the power goes out, your lights and refrigerator (and television and radio) are not affected. Second, due to the cost of an off-grid system, many homeowners find themselves forced to conserve energy rather than expand the system to generate more power. This is very appealing to the environmentally-minded.
We have installed a number of these systems where the grid is available but the homeowner has experienced unreliable power in the past or believes that he/she will be subject to power outages in the future. We also have a number of property owners installing it just for philosophical reasons, for the desire to be independent of the grid and the “gaming” to which utility companies and their power suppliers have subjected customers in the past.