What is solar energy? Definition and examples
Solar energy refers to capturing the energy from the Sun and subsequently converting it into electricity. We can then use that electricity to light up our homes, streets, and businesses, and power our machines as well. We can also use the term solar power with the same meaning.
The Sun’s energy is in the form of solar radiation. Solar radiation makes the production of solar electricity possible.
China is the world’s largest generator of solar energy. Today, it has a solar energy capacity of 130 gigawatts.
According to BBC Future Now:
“China has more solar energy capacity than any other country in the world, at a gargantuan 130 gigawatts. If it were all generating electricity at once, it could power the whole of the UK several times over.”
How does solar energy work?
A photon is a basic unit that makes up all light; it is a bundle of electromagnetic energy.
When photons strike a solar cell, they loosen electrons from their atoms. If we attach a conductor to a cell’s negative and positive sides, we have an electrical circuit.
When the electrons flow through the circuit, they generate electricity.
Solar panel – solar cell – solar array
Solar panels (solar modules) consists of many solar cells. When there are many panels wired up together, we have a solar array.
The amount of electricity a solar panel produces depends on three factors:
- Its size.
- The efficiency of the solar cells within that panel.
- How much sunlight hits the solar panel.
Solar energy – renewable energy
Solar energy is renewable energy. Renewable energy is energy whose source never runs out. We can never use up the energy source completely.
Solar energy, wind energy, and geothermal energy, for example, have renewable sources of energy in a human timescale. The energy from the Sun, in our personal timescale, never runs out. Wind is always there, and heat from below Earth’s surface (geothermal energy) is continuous.
Biomass – energy from plants and other organic material – is also renewable. Humans have been burning wood to heat their homes and cook their food for thousands of years.
Generating electricity when it’s cloudy
Solar power electricity systems or photovoltaics (PV) do not need direct sunlight to work. Even on a cloudy day, they can still generate electricity.
Solar energy – benefits
The UK’s Energy Saving Trust lists these four benefits for households that use solar energy:
- Sunlight is free. Therefore, as soon as you have paid for the initial installation, your electricity costs are virtually free.
- The UK government has a Feed-in Tariff scheme. The scheme pays people for the electricity they generate, even if they use it. Many countries across the world have similar schemes.
- Sell electricity to the grid. The electricity grid will pay households for the electricity that they export through the UK’s Feed-in Tariff scheme. Similar schemes also exist in other countries.
- Lower carbon footprint. Solar energy is a green renewable energy. It does not release carbon dioxide and other gases that contribute to climate change.
A typical PV system for an average household, for example, could save approximately 1.2 to 1.7 tonnes of carbon annually.
Global temperatures are currently rising at progressively accelerating rates. If we do not take drastic action soon, we may have a serious problem by the middle or end of this century.
The Sahara desert could generate more electricity than the world needs just with solar and wind energy.