Solar energy is one of the fastest and most sustainable ways to reduce your carbon footprint and make a positive impact on the environment. It's also becoming more affordable as technology continues to improve and the federal government offers tax credits and rebates for renewable energy installations.
In addition to electricity, solar systems can also power your home's heating, cooling and water pumping needs. In areas with net metering, you can feed excess power back into the grid when your panels produce more than you use.
Photovoltaic cells are a key component of solar panels. They are also used to power calculators, watches and lighted road signs.
A PV cell is a semiconductor material that absorbs sunlight and generates electricity. When the light hits the semiconductor, it knocks loose a number of electrons from its atoms.
The stray electrons then drift freely inside the cell. This enables the formation of an electric field between the positive and negative sides of the semiconductor.
The strength of this electric field determines the amount of electricity that can be produced by the solar cell. This is called a “fill factor” and the higher the fill factor, the more efficient the cell.
Concentrating solar power
CSP is an alternative energy system that uses mirrors or lenses to concentrate a large amount of sunlight onto a receiver, converting the concentrated light into heat. The heat is then used to power steam turbines and other devices that produce electricity.
Some industrial processes can also be directly decarbonised using heat (also known as solar thermoelectricity). This form of power is more versatile than other thermal-based plants, such as geothermal or coal.
Concentrated solar power can be built in a variety of configurations, including linear concentrator systems and parabolic troughs. Linear systems have a number of collectors that are aligned in parallel rows. Parabolic troughs, on the other hand, have long parabolic reflectors that focus sunlight continuously onto a receiver tube.
Solar furnaces are a collection of curved mirrors and mirrored surfaces that capture the sun’s rays and reflect them to a single point where the energy gets focused. This is a great way to harness the suns power and use it in several different ways - for instance, to create electricity or cook food.
There are a few limitations with the way that solar furnaces work, but they are not insurmountable. If two mirrors are pointing at a focus, they won’t generate enough energy to cook a meal or heat up a room, but once you have ten or more, it will start to get closer to those levels.
One of the world’s largest solar furnaces, Odeillo in France, is 54 metres high and 48 metres wide and features 63 heliostats (mirrors). It was built between 1962 and 1968 and started operating in 1970.
Solar power towers
Solar power towers, also known as heliostat plants, use a large number of flat mirrors to concentrate sunlight on a receiver at the top of a tall tower. The heat-transfer fluid heated in this receiver is then used to generate steam which, in turn, runs a turbine generator to produce electricity.
In early designs these plants utilised water to directly generate steam, but this has now been replaced by molten salts. This enables the plants to store the sun’s energy and to continue generating electricity even when there is no sunlight.
A typical solar tower uses hundreds to thousands of heliostats to reflect sunlight onto the tower mounted receiver at the top of the tower. The heat is then transferred to a liquid storage tank. The molten salt is then heated to a high temperature, typically above 500°C, and then stored in the tank until it is used to generate steam which runs a turbine.
Solar Impulse II
Solar Impulse II is a solar-powered plane that is covered from nose to tail with 17,248 photovoltaic cells. These cells collect energy from the sun to power the four propellers that keep the aircraft flying at night.
This solar-powered airplane was built to show people that there is a better way to travel. It aims to promote clean energy and help make the world more sustainable for future generations.
The project began with a simple idea: could a flying machine be built using only solar energy?
The team needed to improve performance, modify the cockpit ergonomics, build leak-proof electrical circuits and increase battery capacity. They also wanted to keep the airplane as light as possible.