How does a Solar Photovoltaic (PV) power system work?

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When Sun rays fall on photo-voltaic modules, they produce DC electricity which is converted to AC electricity by an  inverter then is fed into the main electric system of the building.

Now to understand this whole concept of Solar power plant we need to understand some basic concepts first.

Solar cell – The building block of PV Systems

A solar cell is a semi-conductor device which captures sunlight and convert it into electricity. The amount of electricity generated by a solar cell  directly depends on amount of sunlight falling on the cell. The electricity generated depends on the intensity of sunlight, the area of the cell, and the angle at which sun rays fall on the solar cells.

In common, all solar cells, irrespective of the technology and material used, have only two terminals, viz positive and negative terminals. The upper and bottom surface acts as positive and negative terminals and a P-N junction is sandwiched between the two surfaces. When we connect the upper and bottom terminals to a load, electricity flows due to voltage difference.

How Solar Cell Generates Electricity?

Sunlight falling on earth is basically a bundle of photons or very small energy packets. Each photon in a bundle has a finite amount of energy. In a solar spectrum, there are many photons of different energy.

When photons in the sunlight fall on solar cells, they are absorbed by the semiconductor material due to deficiency in the energy. Then free electron-hole pairs are generated. When we connect the solar cells to a load, the electrons(negative charge particles) and holes(positive charge particles) separate at the junction.

A potential difference is developed between the terminals and we get a voltage across the terminal. Voltage at the terminal is used to drive the current in the circuit. The current generated by solar cells is direct current in nature.

Solar PV electric panels do not require bright sunlight in order to operate, meaning that you can still generate electricity on cloudy days too, however in general the greater the intensity of light the higher the flow of electricity. Although, due to the reflection of sunlight, days with slight cloud can result in higher energy yields than days with a completely cloudless sky.

It is important to realize that you can only use your free solar electricity when it is being generated – so unless you also invest in batteries to store power for use in the evenings and at night, you will need to pay for your energy use as normal when the panels are not producing electric.

How the Electricity is Converted for use

Direct Current (DC) needs to be converted into alternating current (AC) so it can be used in a domestic building; this is performed by an inverter. The AC electricity then passes via the generation meter, which measures how much electricity has been created, and on to the consumer unit where it can be fed into the building load for use or exported back to the national grid via the electricity meter.

In off-grid standalone systems, where the solar system is not connected to the grid, batteries are used to store energy produced by the solar plant for future use.

 

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