Solar photovoltaic power generation principle and system composition

Solar photovoltaic power generation is based on the principle of photovoltaic effect, the use of solar cells to directly convert solar energy into electricity. Whether used independently or connected to the grid, the photovoltaic power generation system is mainly composed of solar panels (components), controllers and inverters, which are mainly composed of electronic components, but do not involve mechanical parts.

The working principle of solar photovoltaic power generation

Solar photovoltaic power generation relies on solar cell modules, using the electronic characteristics of semiconductor materials, when the sun shines on the semiconductor PN junction, due to the P-N junction barrier area produces a strong built-in electrostatic field, and thus produces non-equilibrium electrons and holes in the barrier area or produces non-equilibrium electrons and holes outside the barrier area but diffused into the barrier area. Under the action of the built-in electrostatic field, each moves in the opposite direction, leaving the barrier region, resulting in an increase in the P region potential and a decrease in the N region potential, thus generating voltage and current in the external circuit, converting light energy into electrical energy.

Second, solar photovoltaic power generation system composition

1. Solar cell modules

A solar cell can only produce about 0.5V of voltage, which is far lower than the voltage required for actual use. In order to meet the needs of practical applications, solar cells should be connected into modules. A solar cell module contains a certain number of solar cells that are connected by a wire. For example, the number of solar cells on a module is 36, which means that a solar module can produce about 17V voltage.

The physical unit sealed into a solar cell connected by a wire is called a solar cell module, which has certain anti-corrosion, wind, hail and rain prevention capabilities, and is widely used in various fields and systems. When the application field requires high voltage and current and a single component cannot meet the requirements, multiple components can be composed of solar cell arrays to obtain the required voltage and current.

2. Dc/AC inverter

A device that converts direct current into alternating current. Since the solar cell emits direct current, and the general load is AC load, the inverter is indispensable. Inverter according to the operation mode, can be divided into independent operation inverter and grid-connected inverter. Independently operated inverters are used in independently operated solar cell power generation systems to power independent loads. Grid-connected inverters The solar cell power generation system used for grid-connected operation feeds the electricity emitted into the grid. Inverters can be divided into square wave inverters and sine wave inverters according to the output waveform.

3. Design of power distribution room

Because the grid-connected power generation system has no battery and solar charge and discharge controller and AC and DC distribution system, if conditions permit, the grid-connected power generation system inverter can be placed in the low-voltage distribution room of the network, otherwise as long as a separate low-voltage distribution room of 4 to 6 square meters can be built.