Solar power generation system
Solar power generation system is used to obtain solar energy, also known as Photovoltaie (abbreviated as PV) system. The word “Photovoltaic” comes from the Latin words photo (light) and voltaic (energy). Photovoltaic devices capture the energy in sunlight and convert it into electricity, which means they use sunlight energy. Do not confuse solar power generation systems with solar thermal utilization systems that use solar energy to heat other materials (such as water). As shown in the figure below, the power generation system and the heat utilization system are quite different in appearance and operation. Several different types of solar power systems are discussed below.
Off-grid (or stand-alone) solar power generation systems are designed to replace or supplement conventional power supply, and are usually used in rural or remote areas, where power supply is lacking due to the high cost of grid extension. The off-grid system uses solar power to charge the battery, and then uses the stored power when needed. Then, use the battery to supply power to household appliances such as lamps, water pumps, and refrigerators. The battery can directly supply power to low-voltage appliances (such as 12V DC lamps), or the battery voltage can be converted into equivalent AC power through an inverter connected to the battery. Used in conventional AC appliances (such as computers, televisions, radios, etc.).
The scale of the off-grid system can be as small as a system composed of a single photovoltaic module, battery, and controller, to a large, expensive system that is used in conjunction with complex control equipment and large backup generator sets.
Grid connected system
Grid-connected or grid interactive solar power generation system is the focus of this site. Unlike off-grid systems, grid-connected systems are not intended to replace the grid. Grid-connected systems usually appear in urban areas covered by the grid, and the electricity generated by the photovoltaic system is fed into the grid instead of being stored in batteries. In this system, the power grid is used as an energy storage medium. When the building needs electricity, the power grid can inject electricity. An important advantage of this system is that it does not need to provide all the power in order to fully meet the power needs of the building like an off-grid system. Buildings can be powered by photovoltaic systems, grids or a combination of the two, which means that the scale of the system can be large or small according to the owner’s needs. The surplus power of the photovoltaic system will be output to the grid, and system owners in many regions will purchase this part of the power.
The main components of the grid-connected photovoltaic department include photovoltaic display, inverter and metering system. In addition to these main components, cables, combiner boxes, protective equipment, switches, lightning protection and identification are also required.
Centralized grid-connected photovoltaic system
The existing power system consists of centralized power stations that use different energy resources such as coal, natural gas, and hydro-diesel, and supplies power to end users through transmission lines and distribution systems. The power station is directly connected to the transmission line, but the power consumption of the power station is in the actual location such as the factory, store and home where the end user is located.
The operation mode of the centralized grid-connected photovoltaic system is the same. Large-scale photovoltaic power stations are directly connected to transmission lines. The grid-connected centralized photovoltaic system can be as small as 50kWp, but in recent years, Europe has built a large-scale system of 60MWp. There are also companies planning to build grid-connected photovoltaic power plants of more than 1GWp, and many photovoltaic power plants will be built soon.
Distributed grid-connected photovoltaic system
This type of grid-connected photovoltaic system is the most common type of photovoltaic system distributed in the grid. There are two typical systems: commercial systems and residential systems.
Commercial systems are generally larger than 10kWp. They are built on buildings such as factories, commercial facilities, office buildings, and shopping malls. In a typical case, the power generated by this type of system is consumed by the internal load of the building, so the surplus power is not exported to the grid.
Residential residential systems refer to those systems installed in homes, which are generally smaller than commercial systems, and their typical scale is between 1 and 5kWp. The power generated by this type of system is first consumed by the load in the daytime house, and the surplus power is fed into the grid to supply power to nearby buildings.