What is solar energy and how does it work?
By now you may well be more familiar with solar panels and the practicalities of owning them. But you might not have given as much thought to the reason why they work so well: solar energy.
What is solar energy?
Solar energy is heat and light produced by the nuclear reactions in the sun’s core and emitted into space. A significant amount of this heat and light reaches Earth.
Solar energy is one of the most abundant energy sources in the world, with the amount reaching us equalling far more than we need. NASA notes that around 342 watts of solar energy fall on every square metre of Earth per year, which is approximately 44 quadrillion watts of power.
Because of this, solar energy can be used for solar power, which is used to generate electricity, and solar thermal energy, which is used to generate heat. It can be used at scale, making it a sustainable alternative to fossil fuels, which release carbon dioxide and trap heat in the atmosphere, warming the global temperature.
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How does solar energy work?
The way solar energy works depends on the technology used to harness it. Here are some examples.
In photovoltaics (PV), energy from the sunlight which shines onto a solar panel is absorbed by the PV cells in the panel. These cells are placed between materials which have semiconducting properties, which means they conduct electricity in some circumstances but not others.
The cells create electrical charges, which move in response to the electrical field in the cells and generate a direct current. The current sends electricity into a solar inverter, which converts the electricity to an alternating current so it can be used in the home. Excess electricity can be stored in a battery system, or fed to the National Grid if you don’t have one.
Concentrated solar-thermal power
Concentrated solar-thermal power (CSP) uses mirrors to reflect and concentrate sunlight onto a specific point, known as a receiver. The sunlight heats the fluid in the receiver, creating thermal energy which can power turbines to generate electricity. CSP is often used on an industrial scale, but solar-thermal panels can be installed on a roof and connected to a cylinder where hot water can be stored and used in the home.
Because CSP systems use mirrors, they have to be protected from outside elements like dust and inclement weather, which can damage the surfaces.
Passive solar design
Buildings which incorporate passive solar technology are designed to collect heat from solar energy and use it to warm up the property. This heat is stored in materials in the building, which are referred to as thermal mass, and distributed throughout when the sun goes down. Thermal mass could be concrete, brick, stone or tile. A large window is needed so the sunlight can enter the building, as well as a shade to prevent overheating during the summer months.
Solar process heat technology
Larger buildings, like those used for commercial instead of residential purposes, can use solar process heat technology, such as space heating. Solar energy can be absorbed using a solar ventilation system, which is normally a metal panel on a south-facing exterior wall. There are holes in this panel, so air can pass through and enter the ventilation system, which heats the air and saves on heating bills.
Solar process heat technology can also be used for cooling buildings, with thermally activated cooling systems (TACS). They are expensive to invest in upfront, but cool the air in warmer climates. A solar absorption system uses thermal energy from the sun to evaporate coolant into the air, while a solar desiccant system uses the energy to generate desiccants which dry and therefore cool the air.
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Advantages of using solar energy
- Solar energy is a renewable resource, which means it won’t run out. As discussed above, Earth receives more sunlight than we could ever use.
- Aside from the initial installation of the system you choose, there aren’t any fuel costs when using solar energy because it’s a natural resource.
- Solar energy doesn’t release any greenhouse gases or other hazardous substances, making it safer and more environmentally friendly than non-renewable energy sources.
Disadvantages of using solar energy
- Solar energy depends on the weather, so performance will decrease if cloud coverage is very opaque and there is no solar light passing through.
- Installing solar panels can have a high cost upfront, although you will normally see a return on your investment within five to seven years, while systems can last 20-30 years.
As you can see, there are many benefits of using solar energy for domestic and commercial purposes alike. Interested in using solar energy for your own home? At Otovo, we run a network of reliable, local installers, all of whom are certified by consumer protection organisations and regularly audited to ensure consistent quality. Please don’t hesitate to get in touch with us if you have any questions.