We’ve all seen them, but do we know much about these eco-friendly energy makers?

1. Solar cell technology started way back in the 1800s by the French physicist Antoine–César Becquerel. While experimenting with a solid electrode that was dipped in electrolyte solution, he was able to see a photovoltaic (PV) effect. He even saw a voltage develop when the sunlight fell on the electrode.

The earliest solar cells and panels that were created were extremely inefficient and the energy conversion received from the sun stood under 1%. In 1954, three American researchers, Gerald Pearson, Calvin S. Fuller and Daryl Chapin were able to develop a new solar panel that had the efficiency level of 6% when it came into contact with direct sunlight.

2. The country that has the most solar panels in the world is gloomy-skied Germany. A global leader in electricity generated through solar panels, it produces almost half of the world’s total solar electricity. Fifteen of the 20 biggest solar panel plants in the world are in Germany, in line with the decision by the German government to phase out all of its nuclear power plants by 2020. Germany’s photovoltaic solar electricity now forms almost 10-15% of the total electricity production in this country at peak times. Prices of PV systems have decreased more than 50% in the last five years. The German government aims to have 66GW of installed solar PV capability by 2030.

3. Photovoltaic (PV) cells are made from layers of semi-conducting material, usually silicon. When light shines on the cell it creates an electric field across the layers. The stronger the sunshine, the more electricity is produced.  Groups of cells are put together in panels or modules that can be mounted on your roof. The power of a PV cell is measured in kilowatt peak (kWp). That’s the rate at which it generates energy at peak performance in full direct sunlight during the summer. PV cells come in a variety of shapes and sizes. Most PV systems are made up of panels that fit on top of an existing roof, but you can also choose to fit solar tiles.

4. Solar electricity systems, also known as solar photovoltaics (PV), capture the sun’s energy using photovoltaic cells. These cells don’t actually need direct sunlight to work – they can still generate some electricity on a cloudy day. The cells convert the sunlight into electricity, which can be used to run appliances.

5. An average system is 2.9 kWp and will cost around £11,700 (including VAT at 5%). Most domestic PV systems cost around £3,500 to £4,500 per kWp installed, but shop around because costs do vary between installers. Panels built into a roof may look neater, but they cost more than those that sit on top.

6. Solar PV doesn’t need much maintenance once they are fitted, apart from keeping the panels clean and making sure trees don’t overshadow them. The panels should last 25 years, but the inverter is likely to need replacing during this period, at a cost of around £1,000. >

7. The Feed-in Tariff (FiT) was a big incentive in having solar panels fitted, but unfortunately the rewards are about to be slashed by half. The Department of Energy and Climate Change has announced that the FiTs, which currently pay 43.3p per kilowatt hour (KWh) generated, plus a further 3.1p for each KWh that is exported back to the National Grid, is set to be halved. People who have solar panels installed after December 12 this year will only earn 21p for each KWh hour generated. This means that it will take around 20 years to earn back the money from the installation, but you will still make and save about £640 per year from the electricity generated. If you had solar panels already, however, you will still receive the original tariff. This is because back in April 2010, the government pledged to increase the Feed-in Tariff in line with inflation for the next 25 years. The new proposed rate is still at consultation phase but looks hopeful.

8. Soaring energy prices are a big incentive for having solar panels set up. Once you’ve paid for the installation, your electricity will be powered by sunlight, which
is, of course, free. You will get some money back from the Feed-in Tariffs and you will cut your carbon footprint: solar electricity doesn’t release any harmful carbon dioxide (CO2) or other pollutants. A typical home solar PV system could save over a tonne of CO2 per year – that’s more than 30 tonnes over its lifetime.

9. Solar water heating can provide most of the hot water for your home, particularly in the summer months. Solar panels, called collectors, are fitted on your roof. They collect heat from the sun and use it to heat water stored in a hot water cylinder. Solar water heating panels can either be evacuated tubes or flat plate collectors. The cost of installing a typical solar water heating system is around £4,800 (including VAT at 5%). You may be able to receive payments for the heat you generate from a solar water system through the government’s Renewable Heat Incentive. This is the first financial support scheme for renewable heat of its kind in the world, and should be launched in October 2012.

10. The total amount of installed solar power in the UK has jumped from 26 megawatts (MW) before the FITs scheme started on 1 April 2010, to 77.8MW at the end of March this year, according to the Department of Energy and Climate Change (DECC). This increases the number of solar photovoltaic systems in the UK taking part in the FiTs scheme to 28,505, and as their price tag steadily drops, this figure is firmly on the rise.

The natural way
Renewable energy refers to fuel that is taken from natural resources and is naturally replenished. This means that it cannot run out over time, unlike energy from finite resources such as oil, coal and gas. Here is an overview of the main types of renewable energy:
 
Wind power: The power of wind has been used for many years to produce mechanical power for milling grain and pumping water. But thanks to wind turbines, it has now become one of the cleanest and safest ways to generate electricity. The resulting power is either exported to the grid for local use or to power a single, standalone unit.
 
Biomass: Any plant matter that is grown specifically for combustion to generate heat or electricity is called biomass. There are five categories of biomass, which include: virgin wood, high-yield crops, agricultural residues, food waste and industrial waste. Biomass is a carbon-neutral process, so if trees are felled for fuel, more trees are planted so that the carbon released during the combustion of the wood is reabsorbed by the new trees.
 
Hydropower: This refers to the energy contained in moving water, which is then harnessed to generate electricity. Since water is about a thousand times denser than air, even a slow-flowing stream of water can yield a considerable amount of power. The rain, tidal waves and streams can all contribute to hydro power and it accounts for around 2% of the electricity used by the UK.
 
Geothermal power: The form of energy that is stored in the earth. It occurs as a result of the sun shining and letting off heat energy, which is absorbed  into the ground. This power is usually harnessed with the help of a ground source heat pump. The pump extracts the energy from under the ground and allows it to be used.
 
Biofuels: These are any kind of liquid or gaseous fuels that originate from plants to be used for transportation. They are kind to the planet because although burning the fuels releases carbon dioxide into the air, growing plants do absorb a comparable amount of CO₂ from the atmosphere which means they are classed as carbon neutral.

Sarah says... ‘Energy efficiency should be top of the priority list for all homeimprovement work which is carried out these days.’

 Images: Getty