Stand-alone solar electricity systems or solar home systems (SHS) are used when no electricity grid is available. A battery is needed to ensure the availability of electricity at night or at periods with little bright sunlight. Solar Home Systems are often used to cover the electricity needs of a household. Small systems (commercially available as a SHS kit) cover the most basic needs (lighting and sometimes TV or radio), larger systems can also power a water pump, wireless phone, refrigerator, electric tools (drill, sewing machine, etc) and a VCR. The system consists of a solar panel, a control unit, battery storage, cables, the electric load and a support structure.
1. solar panels
How much PV do I need for my house?
If you wanted to completely replace your current electrical purchases from the utility with a PV system, you could look at your kWh usage on your electric bills for a year, calculate a daily average, and divide that by the number of average daily sun hours for your location.
(3600 kWh/yr divided by 365 days/yr equals approximately 10 kWh/day, divided by 5 sun-hours per day (for locations in Murcia , South of Spain, equals 2 kW. This would indicate that a 2-kW system would, over the course of an average year, produce enough energy to replace the power you are currently using.
However, if you design an energy efficient home, you could cut the annual electricity usage dramatically, reducing the size of the system. In the real world, the majority of home systems range from 1 kW to 2 kW. Where you live, if you are on the grid or off, and how you live, will dictate the size of your system, and its ultimate cost and value.