Solar power works by converting energy from the sun into power. There are two forms of energy generated from the sun for our use – electricity and heat.
Both are generated through the use of solar panels, which range in size from residential rooftops to ‘solar farms’ stretching over acres of rural land.
Key words about solar energy
*Solar cell – Solar cells convert the light from the sun into electricity. Many solar cells can be put together to make a solar panel. Solar cells are made from a material called silicon.
*Solar panel – Solar panels are used to produce electricity. They can be found on buildings but can also be used on a solar farm to harvest the power of the sun. Solar panels are made from lots of solar cells.
*Silicon – Silicon is a chemical element found in the earth’s crust. Silicon is used in computer chips, solar cells and in other electronic devices.
*National Grid – The National Grid is the name given to the network of pylons and power lines that transport electricity to our homes, schools, offices and businesses.
Is solar power a clean energy source?
Yes, solar power is a renewable and infinite energy source that creates no harmful greenhouse gas emissions – as long as the sun continues to shine, energy will be released.
The carbon footprint of solar panels is already quite small, as they last for over 25 years. Plus, the materials used in the panels are increasingly recycled, so the carbon footprint will continue to shrink.
When was solar power discovered?
Solar energy was used by humans as early as the 7th century B.C. when humans used sunlight to light fires by reflecting the sun’s rays onto shiny objects. Later, in 3rd century B.C., the Greeks and Romans harnessed solar power with mirrors to light torches for religious ceremonies.
In 1839 and at the age of just 19, French physicist Edmond Becquerel discovered the photovoltaic (PV) effect while experimenting with a cell made of metal electrodes in a conducting solution. He noted that the cell produced more electricity when it was exposed to light – it was a photovoltaic cell.
In 1954 PV technology was born when Daryl Chapin, Calvin Fuller and Gerald Pearson developed the silicon PV cell at Bell Labs in 1954 – the first solar cell capable of absorbing and converting enough of the sun’s energy into power to run everyday electrical equipment.
Today satellites, spacecraft orbiting Earth, are powered by solar energy.
How exactly is electricity from solar energy produced?
Solar panels are usually made from silicon, or another semiconductor material installed in a metal panel frame with a glass casing. When this material is exposed to photons of sunlight (very small packets of energy) it releases electrons and produces an electric charge.
This PV charge creates an electric current (specifically, direct current or DC), which is captured by the wiring in solar panels. This DC electricity is then converted to alternating current (AC) by an inverter. AC is the type of electrical current used when you plug appliances into normal wall sockets.
Solar Panels
Solar panels are made up of individual cells that have layers of special semiconductor materials that are arranged in positive and negative layers (similar to the setup of a battery). Light energy from the sun shines on solar panels and hits the layers of semiconductors with photons (what makes up sunlight) in order to create a flow of electrical energy. The energy from the photons frees electrons within the semiconductor material which creates direct current (DC) electricity. Wiring connected to the positive and negative sides of the cell harness that electrical current using wires that are connected to the panel which carry the electricity to an inverter. Here the electricity can be converted into alternating current. Solar panels can link together to provide either all or a portion of the power needed for a home or business to run.
What’s the difference between solar PV panels and solar thermal panels?
There are two main types of solar energy technologies—photovoltaics (PV) and concentrating solar-thermal power (CSP).
Solar PV panels generate electricity, as described above, while solar thermal panels generate heat. While the energy source is the same – the sun – the technology in each system is different.
Solar PV is based on the photovoltaic effect, by which a photon (the basic unit of light) impacts a semi-conductor surface like silicon and generates the release of an electron. Solar thermal is less sophisticated and simply the direct heating of water (or other fluids) by sunlight. For domestic use, solar thermal panels are also installed on a roof facing the sun, heating water stored in a hot water cylinder and so providing hot water and heating. On a larger scale, solar thermal can also be used in power stations.
What are solar farms?
Solar farms, also known as solar parks or solar fields, are large areas of land containing interconnected solar panels positioned together over many acres, to harvest large amounts of solar energy at the same time. Solar farms are designed for large-scale solar energy generation that feed directly into the grid, as opposed to individual solar panels that usually power a single home or building.
Can solar power be generated on a cloudy day?
Yes, it can – solar power only requires some level of daylight in order to harness the sun’s energy. That said, the rate at which solar panels generate electricity does vary depending on the amount of direct sunlight and the quality, size, number and location of panels in use.
Who are the largest producers of solar power worldwide
As of 2022, China is the largest producer of solar powered electricity generation in the world. The US comes in second, followed by Japan, Germany and India.
Solar Energy in Kenya
The 50 MW Garissa Solar Power Plant
The Garissa Solar Plant is the largest grid connected solar power plant in East & Central Africa. This is the first time that Kenya has developed a major solar power plant to harness its abundant solar energy resource to diversify the power generation mix and reduce energy costs. Currently this project is contributing about 2% of the national energy mix and has significantly led to a reduction of energy costs in the country thereby promoting the development of clean, reliable, sustainable and affordable electricity.
