Standalone Solar Home Systems (SSHS)
In an SSHS (also called off-grid system), the photovoltaic (PV) module is charging a battery via a solar charge controller. The controller makes sure the battery is charged properly (i.e, at proper constant nominal voltage – 12V) and protects it against overcharging. DC load (Direct Current appliances), if any, can be connected directly to the solar charge controller.
For instance, one 140W PV module oriented full south produces an estimated 215 kWh of electrical energy per year (see chart).
In the sunniest day of the year in January, an average of around 740Wh of energy is stored in the battery.
In the least sunny day of the year, an average of around 470Wh of energy is stored every day in the battery.
At 12V, an 180Ah battery can store up to 2,160Wh of energy (12 x 180), i.e, 3 days of the sunniest day production.
All this energy readily available in the battery can be converted to AC (Alternative Current) power via the use of a sine wave inverter, thus supplying AC electricity to AC appliances at a nominal voltage of 220V.
This very simple concept system makes the installation quick and easy, and the maintenance almost free.
Example of demand profile calculator: