Harnessing solar energy for electricity is referred to as photovoltaic energy generation. The principle behind the operation of solar panels is the photovoltaic effect, and the electrical energy produced from solar radiation is called photovoltaic energy.
A single PV cell typically produces 1-2 watts of photovoltaic energy. To achieve higher voltages, PV cells are connected in series; for higher currents, parallel connections are made.
PV arrays can be connected to a utility grid or set up as a standalone or off-grid system. When connected to a grid, other equipment, such as batteries or inverters, are required.
Photovoltaic energy generation refers to harnessing solar energy for electricity
Sun is the ultimate source of energy; if we could harness solar energy completely, then there would be no energy crisis. Harnessing solar energy for electricity is referred to as photovoltaic energy generation. The principle behind the operation of solar panels is the photovoltaic effect, and the electrical energy produced from solar radiation is called photovoltaic energy. Let’s take a closer look at the photovoltaic effect and its associated energy.
Photovoltaic Energy and the Photovoltaic Effect
Photovoltaic energy is the largest renewable energy source available. It is clean energy, obtained by converting solar radiation into electricity. Photovoltaic energy is a direct current in nature. To utilize solar energy in our day-to-day use, the photovoltaic energy from solar panels is converted into alternating current using inverters.
Solar panels use the photovoltaic effect to produce photovoltaic energy; conversion is based on the photovoltaic effect. So, what exactly is this effect? The photovoltaic effect is the phenomenon that converts the solar radiation falling on a solar panel into voltage or current. Depending on the irradiation, the voltage generated in the photovoltaic cell or solar cell varies.
How Does the Photovoltaic Effect Work?
Photovoltaic cells are semiconductor devices containing both P-type and N-type materials forming a PN junction. Similar to a PN junction diode, an electric field is established across the junction due to the movement of electrons towards the positive P side and holes to the N side.
When light falls on the PV cell, the photons, which are the electromagnetic energy bundles present in the solar radiation, are absorbed by the cell. The energy associated with the photon gets transferred to the charge carried in the PN junction. In this way, light excites the electrons to the conduction band and starts a free flow of electrons until the light waves are present. This is the process that is happening inside each PV cell that generates photovoltaic energy.
To utilize the photovoltaic effect, PV cells are fabricated from monocrystalline, polycrystalline, or amorphous silicon. They can also be made from thin films of semiconductor materials, cadmium telluride, or cadmium sulfide. A new trend in solar cells is to use perovskite materials, as they offer high conversion efficiency at a low cost. The table below gives the conversion efficiency of different types of PV cells.
This table shows the conversion efficiency of different types of PV cells
A single PV cell typically produces 1-2 watts of photovoltaic energy. To achieve higher voltages, the PV cells are connected in series; for higher currents, parallel connections are made. The larger units of PV cells are called PV modules or panels. Modules connected together are called arrays. The arrays can be connected to the utility grid or can be set up as a standalone or off-grid system. When connected to the grid, other equipment, such as batteries or inverters, are required.
The Advantages of Using Photovoltaic Energy
The advantages of using photovoltaic energy include:
- It is renewable, inexhaustible, and non-polluting. Since it is clean energy, there is no release of harmful gases, such as carbon monoxide or nitrogen dioxide.
- The generation of photovoltaic energy is noiseless and suitable for residential areas.
- PV cell installation is easy, making it a suitable choice for residential areas, remote locations, and sparsely inhabited areas.
- The most expensive part of setting up a photovoltaic energy generation unit is purchasing and installing solar panels; operation and maintenance costs are minimal.
The Disadvantages of Using Photovoltaic Energy
The disadvantages of using photovoltaic energy include:
- The conversion efficiency of PV cells is low.
- Harnessing sunlight for photovoltaic energy generation is limited by the intermittent nature of sunlight. Generation is not possible at night or when the weather is cloudy. The shade of trees or buildings also prevents irradiation from falling directly on the solar panels.
- The fragile nature of PV cells makes them vulnerable to damage.
- Photovoltaic energy is DC in nature, and an additional inverter system is required for DC to AC conversion.
- Transmitting solar energy long distances is not efficient.
- To utilize photovoltaic energy when sunlight is not present, batteries are required. This increases the cost of the PV system.
Where Can Photovoltaic Energy Be Used?
Applications of photovoltaic energy include:
Grid-connected PV systems - In a grid-connected PV system, photovoltaic energy is converted into AC voltage and is integrated into the grid.
Isolated or off-grid PV systems - For powering traffic signs, telecommunication towers, emergency phones, or meters, off-grid PV systems can be used.
Powering remote locations - Installing a PV system in a remote location is more cost-effective than extending transmission lines to such areas. A PV system can be utilized to power residences, health centers, irrigation pumps, off-shore oil platforms, lighthouses, desalination centers, and more.
Space applications - Photovoltaic energy is the primary source of power for artificial satellites, the International Space Center, and space rovers.
Military applications - PV-powered electronic equipment is used by soldiers on the field or on remote bases.
PV-powered vehicles - The placement of PV panels on the roof of vehicles can provide DC power for motors in automobiles and for charging batteries. An aircraft can be supported by PV power by including lightweight PV modules on the wings.
Photovoltaic energy is an excellent solution to sustainable and environmental-friendly energy demands. Cadence’s software can assist in the design of both on-grid and off-grid PV systems.