Small off-grid solar home systems can provide electricity where there is no electric grid.
Very small systems provide DC power only, usually 12 VDC. Systems with inverters also provide AC power, but can also provide DC power as well (mainly for lighting).
Electricity is generated during the day and stored in batteries for use at night for lighting and appliances, but the electricity can also be used during the day.
Typical applications:
- Lighting (LED, low-energy fluorescent)
- Radio and TV
- Low-energy fans
- Charging mobile phones
- Laptop computers
- Energy-efficient / low-energy refrigerators
A small off-grid solar system providing DC power for lighting and AC power for other appliances. During the day the PV modules charge the batteries, and provide AC power for appliances. At night, the batteries provide all the power, for both lighting and AC appliances.
DC appliances need to be used in DC-only systems and the range of DC appliances now available (especially lighting) is extensive. DC appliances are generally more energy efficient than AC appliances – they need to be because they are designed to run on batteries. AC appliances are more widely available and usually lower cost than DC appliances. Decisions need to be made on a case-by-case basis.
It is important to appreciate both the potential and the limits of what can be powered using PV off-grid systems. The battery bank, not the PV array, is the main limiting factor as regards the size of an off-grid PV system. It will usually need to be replaced several times during the working life of the system.
The following appliances are generally not suitable for small off-grid systems because they consume too much power: cookers, water heaters, electric heaters, electric kettles (any appliance that produces heat), air-conditioning units, large halogen security lights.