Solar Panels

There is enough energy from the Sun falling on the UK to provide more than enough energy for all our needs many times over. Globally that is about 20,000 times the amount of energy we currently consume in the form of fossil fuels. In the UK the amount of solar energy equates to about 200 and 1,000 watts per square metre. It is often quoted that you need a solar array smaller than Belgium to provide enough electrical power to meet the current global demand.

The technology for turning the light from the Sun into electricity comes in the form of solar panels. Photovoltaic crystalline panels create a current when exposed to light. A common misconception is that they need heat to work, the opposite is actually true and if they get too hot they will stop working effectively.

They do not need direct sunlight to work but will work more effectively in direct sunlight. Even in the UK where we get a lot of diffuse light from the Sun solar panels will continue to generate electricity. The effectiveness of these panels are improving all the time increasing the amount of power per square metre and the ability to generate power from low light conditions.

There are 3 main types of solar PV technology which are Mono-crystalline, Polycrystalline and Amorphous/Thin Film. There are newer developments such as coloured solar panels that can capture a wider spectrum of the Suns light. Sony is also developing dye sensitized solar cells that work on the same principle of absorbing different wavelengths of the light spectrum. The end result is that less silicon is used creating cheaper panels.

The types of solar products that are commercially available start with the standard photovoltaic panels that most people will recognise. These use either silicon crystals or thin film technologies. The most commonly available panels are crystalline and are manufactured from silicon wafer. The newer amorphous panels use a thin film of silicon on a substrate such as steel and so use less silicon.

Types of solar panels for your home

In the UK solar panels are available as panels and as tiles. Solar tiles although generally more expensive than panels have the advantage of being able to directly replace roof tiles. All retrofitted systems will generally be polycrystalline panels linked in series to form an array. Depending on the size of the array which is measured in kilowatts will dictate that number of panels you will need. Practical limitations such as suitable roof size will usually be the main factor limiting array size. A typical installation ranges from 2.2kWp to a large domestic system of about 3.7kWp.

Solar tiles

For new builds or when a new roof is being fitted to replace old tiling then solar tiles or solar slates can be used. These are designed to replace conventional concrete or slate tiles and be less obtrusive. They produce electricity just like panels but they also do the job of a standard roof tile. Roof tiles particularly the solar slates blend in with the line of the roof rather than being raised up from the roof surface like a solar panel.

How much does a solar panel cost?

As a homeowner looking for a solar power system it will probably not be the type of solar technology you are interested in but the solar panel cost. The cost of solar panels varies depending on the make and model and where you buy it from. It will also make a difference as to whether or not you are buying the panels separately or they are included in the price of an installation.

At the moment solar is still not a cost effective solution at about £5,000 kWp. There are currently many more cost effective technologies that are starting to filter through and we will be seeing the cost per kilowatt fall to match and even surpass that of fossil fuels. Currently with the best widely commercially available panels you can generate about 200 watts per square metre.

Typical solar panel cost in the UK

Solar panel cost per m2 = £640

Cost of a typical 150w panel = £800

As a consumer solar photovoltaic systems have only recently been made cost effective for homeowners because of the FIT's scheme that the government has introduced. You could buy the components and build your own system but you would not be able to claim the feed in tariff payments. The installed cost of a solar power system is going to be higher than if you bought and installed it yourself. However if the panels and the installer is MCS certified then you would benefit from the tariff payments.