A solar home system (SHS) is a standalone offgrid installation of solar and electric power devices. The installation is standalone and not connected to the electricity grid.
The photovoltaic (PV) modules convert the energy of the sun into electrical power upon impact. The electricity is of the form direct current (DC).
In order for the electricity coming from the PV module to be harnessed it has to be stabilised. This is achieved by a device called a charge controller. A charge controller connects to batteries and the load. The charge controller regulates the follow of electricity in the solar home system. A very important function of the charge controller is to monitor the charging of the battery. More precisely it monitors the state of charge (SOC) of the battery.
The loads in the SHS are basically dc loads. Nowadays, there are a variety of dc devices which can be connected to a SHS such as lamps, mobile phone chargers, fans, radios, television sets, USB devices, etc…
When designing a SHS one has to find the balance between the load, the PV modules, the batteries and the charge controllers.