A solar photovoltaic (PV) power generation system is a power generation system that directly converts light energy into electrical energy without a thermal process. Its main components are solar cells, batteries, a controller, and a photovoltaic inverter. Its characteristics include high reliability, long service life, no environmental pollution, and the ability to generate electricity independently or connect to the grid.
Composition of a solar photovoltaic power generation system
A photovoltaic power generation system typically consists of a photovoltaic array, a battery bank (optional), a battery controller (optional), an inverter, an AC distribution cabinet, and a solar tracking control system. High-concentration photovoltaic (HCPV) systems also include a concentrating component (usually a concentrating lens or a reflector).
The functions of each component in a solar photovoltaic power generation system are as follows:
1. Photovoltaic array
A photovoltaic (PV) array, also known as a photovoltaic (PV) array, is a DC power generation unit composed of several photovoltaic modules or panels assembled in a specific manner and supported by a fixed structure. When there is light (whether from sunlight or other light sources), the cells absorb light energy, and opposite charges accumulate at the ends of the cells, generating a "photovoltaic voltage." This is the "photovoltaic effect." Under the influence of the photovoltaic effect, an electromotive force is generated at the ends of the solar cells, converting light energy into electrical energy, thus completing the energy conversion.
2. Battery pack (optional)
The function of a battery bank is to store the electrical energy generated by a solar array when exposed to sunlight and to supply power to the load at any time. The basic requirements for the battery bank used in solar power generation are: ① low self-discharge rate; ② long service life; ③ strong deep discharge capability; ④ high charging efficiency; ⑤ low maintenance or no maintenance required; ⑥ wide operating temperature range; ⑦ low price.
3. Battery controller (optional)
A battery controller is a device that automatically prevents batteries from overcharging and over-discharging. Since the number of charge-discharge cycles and the depth of discharge are crucial factors determining a battery's lifespan, a battery controller capable of controlling overcharging and over-discharging of the battery bank is an essential piece of equipment.
4. Photovoltaic inverter
An inverter is a device that converts direct current (DC) to alternating current (AC). Inverters are essential when solar cells and batteries provide DC power, while the load is AC. Inverters can be categorized by operating mode into off-grid inverters and grid-connected inverters. Off-grid inverters are used in independently operating solar power systems to supply power to the load. Grid-connected inverters are used in solar power systems operating in conjunction with the grid. Inverters can also be categorized by output waveform into square wave inverters and sine wave inverters. Square wave inverters have simple circuits and low cost, but they have high harmonic content and are generally used in systems below a few hundred watts and where harmonic requirements are not high. Sine wave inverters are more expensive but can be used with a wider range of loads.
5. Tracking System
Because the angle of sunlight changes constantly throughout the year, with the seasons and the sunrise and sunset, the solar panels must always be facing the sun for the power generation efficiency to reach its optimal state.
Universally used solar tracking control systems worldwide require calculating the sun's angle at different times of day throughout the year based on the latitude and longitude of the installation point. This sun position at each moment of the year is then stored in a PLC, microcontroller, or computer software. In other words, tracking is achieved through computer data theory, relying on calculating the sun's position. This requires data and settings specific to the Earth's latitude and longitude regions. Once installed, it is difficult to move or disassemble; each time it is moved, the data must be reset and all parameters adjusted.
