What is solar photovoltaic system?

Solar photovoltaic systems use solar cells encapsulated in panels called solar modules to capture the sunlight and convert it into electricity. The solar modules produce direct current (DC) from the suns radiation. If the connected loads required alternating current (AC), the DC electricity from the solar modules is converted to AC electricity by an inverter.
There are different types of solar modules and the most common types in the PV market today are called crystalline modules. These modules are made of crystalline silicon, and they have an efficiency of about 15-20 %, which means they convert 15 - 20% of the sunlight they received into useful electricity. There are also other types of solar modules called Thin film modules. These modules have much lower efficiency than crystalline modules, but they cost much less than crystalline modules.

How to store solar electricity?

There are different technologies used to store solar electricity to use it when the electricity production of the PV system is limited, such as nights and raining days. In the developed countries, most PV system installations are connected to the main electricity grid, which is used as storage system. The electricity from the PV system is used by the connected loads, and the surplus is feed into the public grid. The grid company sells this electricity to their customers, and the owner of the PV system takes all electricity he needs from the grid when the PV system is not producing enough electricity. This type of solar PV system is known as grid-connected solar PV system.
If the solar PV system is not connected to the public grid, the energy is stored in rechargeable batteries. The energy demand of the connected loads is then covered by the batteries when the PV system is not producing enough electricity, like nights and raining days. This type of solar PV system is known as stand-alone solar PV system.