How Do Solar Panels Work?

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The global demand for electricity is continuously increasing. More and more resources are being invested into finding new energy sources rather than relying on our finite fossil fuel supply. One of these sources is sunlight.

As of 1954, sunlight can be converted into usable electricity via solar panels. Solar panels are becoming increasingly popular as technology advances and are now widely accessible across the globe. The materials that make up solar panels are changing as technology advances - but the answer to the question "How do solar panels work?" remains the same.

How Do Solar Panels Generate Electricity?

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Solar panels are used to convert our planet’s most abundant energy source, sunlight, into electricity that we can use to power our appliances. This process can be broken down into four key steps:

1. Sunlight shines onto a solar panel, which is made up of many smaller units called photovoltaic (PV) cells. PV cells contain semiconducting materials, such as silicon, which can convert light into electricity.

2. Sunlight is made up of very small particles of energy called photons. Atoms within the semiconductors absorb photons, which excite one of their electrons. This excited electron becomes a free-flowing electrical charge. This is known as the photovoltaic effect.

3. The free-flowing electrons within the semiconductor are forced to flow in a specific direction, producing a direct current (DC) of electricity which can be drawn off for external use.

4. The DC passes through an inverter which turns it into alternating current (AC) electricity. This is the form of current that is needed for most household appliances.

Solar Panel Structure

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The structure of a solar panel is relatively straightforward.

A solar panel is made from a sheet of photovoltaic cells that are organised into different configurations depending on their efficiency and performance requirements.

These PV cells are held together during manufacture with layers of a highly transparent polymer film made from ethylene vinyl acetate (EVA).

Solar panels are designed to be placed outside so that they can be exposed to sunlight. Hence, the top and bottom surfaces are covered with high strength tempered glass and moisture-resistant polymer back sheets respectively.

What is Solar Energy?

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Solar energy is a form of energy produced by the sun. The sun is basically a giant nuclear fusion reactor that is constantly producing energy in the form of photons. These photons then travel to Earth.

The amount of solar energy the Earth receives is vastly greater than the current energy demand. In fact, the amount of sunlight that reaches the Earth’s surface in 90 minutes could fulfil the world’s energy consumption for an entire year. It is no surprise that research is focused towards a ‘solar revolution’ which could one day see all our homes powered by sunlight alone.

The amount of energy that a photon has corresponds can be determined by its position on the electromagnetic (EM) spectrum. Some examples of high energy photons emitted by the sun include gamma rays, X-rays, and ultraviolet radiation (UV rays). In contrast, the heat that we feel from the sun comes from lower energy photons which make up infrared radiation.

The majority of light that makes it to Earth lies in the visible light region. Photons of visible light lie in the middle of the EM spectrum. They have an energy which lies in between photons of infrared radiation and UV rays. Most solar panels are designed to absorb as much visible light as possible. However there are panels in development which can make use of UV or infrared light.

When testing solar cells or solar panels, it is important to mimic the solar energy recieved on Earth as closely as possible. Solar simulators, like the Ossila LED Solar Simulator, provide a standardized spectrum replicating the solar spectrum, in order to test the efficiency of solar cells.

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