Electricity from the Sun
Solar electricity is generated by harnessing the sun’s radiant energy. Solar radiation consists of photons, or particles, which carry the sun’s radiant energy. When they hit solar cells, the photons transfer their energy to electrons in the material of the cells. These electrons, energised by the photons, form an electric current in the conductors of the solar cells.
Solar panels consist of solar cells connected in series and/or in parallel, enclosed by a panel frame with a solar-permeable protective glass in front of the cell. Solar panels are available in many sizes and for many applications.
Various solar cell connections can be used to generate the desired voltage and current. The voltage of a solar panel is the sum of the voltages of the solar cells connected in series. The total current generated by a series connection is the sum of the currents of the cells connected in parallel.
The solar panel produces direct current electricity, which is different from the alternating current that flows in the general electricity grid.
In practice, the DC electricity produced by the panel can be used in the following ways:
- Direct current can be used in DC electrical appliances, such as household appliances (commonly used in areas not connected to the grid).
- Direct current can be converted into alternating current by an inverter and used in appliances that use alternating current, such as household appliances or hot water heaters (common in grid-connected buildings).
- If the DC electricity cannot be used in electrical equipment for a short period of time, it can be stored in batteries and discharged for use as DC or AC electricity. In grid-connected sites, the battery is equipped with an inverter that converts the stored direct current into alternating current when discharged.
Electricity can also be fed into the grid, but you should try to use the electricity you produce yourself. Only alternating current can be fed into the grid, in which case the system also includes an inverter.
An inverter is a device that converts direct current into alternating current and optimizes the terminal voltage of the panels so that the panels produce the highest possible power. An inverter must be purchased as part of a solar power system whenever the system is installed in a location that is connected to the national grid.