An off grid solar system is not connected to the local utility; a household’s electricity is generated by solar panels, sometimes with a backup power source (like a diesel generator or wind turbines). Off grid solar power systems generate energy during the day and charge batteries which provide power at night.
Off grid electricity is common in rural areas far from the municipal grid — especially in remote villages in poorer countries.
Off Grid Solar Design
There are two types of off grid solar energy systems:
- direct-coupled systems consist of a solar array directly connected to a DC load. The energy is not stored in a battery and thus is only able to provide electricity during the day. Not all appliances can run on DC power.
- stand-alone systems use batteries to store excess energy and provide it at night. A charge controller regulates the flow of electricity from the array to the battery bank and the load. Inverters convert DC to AC electricity as most household appliances run on AC power.
Benefits of Going Off the Grid
- environmental: you will know that your home is powered in full or in part by clean, renewable energy, effectively lowering your carbon footprint.
- financial: while going off the grid has higher up-front costs than grid-connected solar, in the long-run the system will pay for itself. That means no more electricity bills! In remote locations, off-grid systems can be cheaper than extending a power line to the municipal grid.
- energy independence: your home will not be subject to power outages from the grid.
- lower energy use: many homeowners go off the grid for environmental reasons. People with such a concern often try to conserve energy by also reducing appliance use.
Disadvantages of Going Off the Grid
- off-grid systems must be carefully designed so that all components harmonize with the electrical load.
- potential for loss of power if your off grid residential solar power system fails.
- battery technology is still in development, and is not the most efficient way to store power. Batteries can also contain toxic chemicals.
How Do You Get Power at Night?
Deep-cycle batteries store energy from the solar modules to provide power at night, and can recover about 80% of the energy they receive. These batteries last five to ten years and can be recycled. Learn more about solar panel batteries.
Is it Expensive to Go Off the Grid?
The up-front cost of off grid solar electric systems is more than grid-tied systems, but in the long-run the system will pay for itself – especially if you concurrently reduce your electricity use. If you live in a remote location, going off the grid is often cheaper than connecting to a grid that is far away.
How Do I Know if My House is Suitable for an Off Grid Solar Panel System?
The main factor for both grid-tied and off-grid solar energy systems is the solar resource: most regions are suitable for solar energy generation. However, some locations may not be able to be fully solar powered and require a wind turbine or diesel generator. You can use the In My Backyard tool from the National Renewable Energy Laboratory to estimate how much electricity solar panels can generate on your roof.
If you use a lot of energy — for example, from computers or TVs – it may be difficult to generate enough energy to offset your use.