A basic off grid solar electric system consists of the following 4 key components:
- The solar panel is the basic component of a solar electric system. The module consists of photovoltaic cells that absorb sunlight and convert it into electricity. The entire process is self-contained – there are no moving parts and no materials are used up or given off. The cells are most commonly made from silicon, one of our most abundant resources on earth. The cells are connected together and encased in a protective shell behind a sheet of glass to form a module or panel. Each panel has a metal frame and is equipped with connectors and can be transported and installed safely and easily.
- The charge controller regulates the flow of electricity from the solar modules to the battery bank. The device senses battery voltage and amongst other things, ensures automatically that the batteries are not over charged. Charge controllers can also log information about the energy generated.
- The battery bank stores all electrical energy generated by the solar array and ensures that it is available at all times. A properly designed system ensures that the battery bank has enough reserve capacity to provide electricity on days when the sun doesn’t shine. If Eskom is available as a back-up source, some systems can automatically use energy from the grid when sunlight has not been adequate.
- The inverter is a device that converts stored electric energy from the battery bank into standard 230 Volt household electricity, ready to power devices like lights, computers, and other household appliances.
- Most inverters also contains a sophisticated battery charger, allowing a back-up source (Eskom or generator) to be utilized to charge the batteries if required.
A solar electric system is designed to supply a given amount of energy every day and it is thus very important to establish the daily energy requirement. In essence such a system can take over from Eskom to become your own private electrical factory!
Grid tied solar PV systems
Grid tied solar systems works a little differently and consists of only 2 key components
All the electric power generated by the solar panels feeds through a mains synchronized inverter directly into your distribution board and offsets the power you would normally consume from Eskom. It will of course only do this during sun hours! If the panels produce more power than what it being consumed at the time, the balance will flow back into the network and it will actually reverse the electricity meter (not all types of meters can do this though). Since no batteries are used, no independent energy can be stored for later use. This means that energy required at night will still be obtained from the network.
For more detailed information, see Solutions – Grid tied systems