The classification and composition of PV system

The classification and composition of PV system

Photovoltaic system is a system that converts solar energy into electricity using solar cell modules and other auxiliary equipment. Solar energy is inexhaustible environmental resource. More and more attention has been paid to its utilization, which has the advantages of sufficient clean resources, safety and long life. The main form of solar energy utilization is PV power generation, which represents the development direction of solar energy and is the most attractive energy utilization technology in the 21st century.
The classification and composition of PV system
According to the classification, the components of PV system are different, including:solar cell module (PV panel), inverter, battery, charging controller, load, distribution box, EMS, diesel engine, power grid.We will introduce you the conventional classification of PV system in this article, and then the hybrid PV system, which is one of the conventional type of PV system,will be described in detail.

The conventional classification of PV system

The conventional classification of PV system is: grid-connected PV system, off-grid PV system, hybrid PV system (energy storage system).

Grid-connected PV system

The grid-connected PV system mainly has two types of mode, one is “spontaneous self-use, surplus electricity access”, the other is “full access”. Generally, the distributed PV power generation system mainly adopts the mode of “self-use and surplus power online”. The electricity generated by solar cells is preferentially supplied to the load. When the load is not used up, the surplus electricity is sent to the power grid.

The grid-connected PV system mainly has two types of Internet access mode,

The configuration basis of system selection :

1.components: open circuit voltage, power, current

2.inverter: MPPT voltage range, output topology, voltage level

3.according to the demand capacity, select the specifications and number of components. Then through the series and parallel assembly of components, select the appropriate inverter.

4.distribution box, cable and other auxiliary materials selection.

Off-grid PV system

The off-grid power generation system converts solar energy into electric energy under the condition of illumination, and supplies power to the load through the solar inverter and charges the battery at the same time. In the absence of light, the battery supplies power to the AC load through an inverter. It is very practical in areas without power grid or frequent power outage. Generally used in remote mountainous areas, no power areas, islands, communication base stations and street lamps, etc.

The off-grid PV power generation system is very practical in areas without power grid or frequent power outage

The configuration basis of system selection :

  1. component: the open circuit voltage, power, current
  2. Inverter:battery voltage, output voltage level
  3. charging controller: battery voltage level, charging mode PWM/MPPT, input voltage range
  4. according to the power size and electricity demand, choose the appropriate inverter, and then in the configuration of battery pack, choose the appropriate charging controller and components.
  5. distribution box, cable and other auxiliary materials selection

The hybrid PV system

The hybrid PV system can be divided into  on/off PV energy storage system, grid-connected PV energy storage system and Micro-grid energy storage system.

On/off PV energy storage system

The PV array converts solar energy into electricity under the condition of illumination, and supplies power to the load through the solar control inverter and charges the battery at the same time. When there is no light, the battery supplies power to the solar controlled inverter and then to the AC load. Compared with the grid-connected power generation system, the system increases the charge and discharge controller and battery. When the power grid fails, the PV system can continue to work, and the inverter can switch to off-grid working mode to supply power to the load. And off-grid PV power generation system is widely used in frequent power outages, or PV spontaneous self-use can not spare electricity to the Internet, self-use electricity price is much more expensive than the grid price, the peak price is much more expensive than the trough price.

The hybrid PV system can be divided into grid-connected PV energy storage system, off-grid PV energy storage system and Micro-grid energy storage system

Grid-connected PV energy storage system

Grid-connected energy storage PV power generation system can store excess power generation and improve the proportion of self-use. The system consists of PV modules, energy storage converters PCS, batteries, grid-connected inverters, current detection devices, loads and so on. When the solar power is less than the load power, the system is powered by solar energy and the grid together. When the solar power is greater than the load power, part of the solar energy supplies power to the load, part of the energy storage converter will be used to store the electricity.

Micro-grid PV energy storage system

Micro-grid PV energy storage system is a new type of network structure, which is composed of distributed power supply, load, energy storage system and control device. The dispersed energy can be converted into electricity locally and then supplied to local load nearby. Micro-grid is an autonomous system that can realize self-control, protection and management.

Grid-connected energy storage PV power generation system can store excess power generation and improve the proportion of self-use

It can be connected to the external power grid or run in isolation. Micro-grid is an effective combination of multiple types of distributed power sources to achieve a variety of energy complementarity and improve energy efficiency. It can fully promote the large-scale access of distributed power and renewable energy, and realize the high reliable supply of various energy forms to the load. It is an effective way to realize the active distribution network and the transition from traditional power grid to smart power grid. The Micro-grid system consists of PV modules, grid-connected inverters, PCS two-way converters, intelligent switching switches, batteries, generators, loads and so on. The PV module converts solar energy into electric energy under the condition of illumination, supplies power to the load through the inverter, and charges the battery pack through PCS two-way converter. In the absence of light, the battery supplies power to the load through PCS two-way converters.

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