What is a Solar PV system?
A Solar Photovoltaic (PV) system is one which converts light directly into electricity on your roof with no waste and no emissions. This electricity is used throughout your home in the same way as the electricity you currently buy from your energy supplier. Solar PV difers from Passive Solar water heaters in that it actually produces electricity whilst a passive system is merely used to heat water or your home.

How does it work?
When light hits the silicon in a solar PV cell, electrical energy is created. This electricity flows through a cable and can be collected or stored at a central point, this can be located in your roof space or any other available space. At this point the electricity is converted from Direct Current (DC) to Alternating Current (AC) and carries on into your household electricity system. The electricity generated by your system can work hand in hand with your existing electrical supply to power your household appliances and lighting or you can chose to only use this energy and disconnect from the grid completeley. It is advisable that if you live in a country that has long winters or a large quantity of overcast days then you also invest in a subsidising system like a wind turbine. During the day you may generate enough electricity from your own system for all your electrical needs. However if you chose to remain on the grid, your needs will be supplemented by your electricity supplier. If during the day you generate more electricity than you need this excess will flow out of your home and back in to the main electricity grid. Off the grid electricity generation must be stored during the day for use at night.

Are you ready to fly solar?
There is absolutely no point in installing a solar system if your home is not already as energy efficient as you can make it.

With 27% of the UK's carbon dioxide emissions coming from domestic energy use, it is important that we consume the energy we need as efficiently as possible.

What systems are available?
There are two types of system available depending on how you chose to fit them. Integrated solar PV systems are available as roofing products which replace conventional roof tiles. This system is not suitable for some roofs and advice and planning may be needed before fitting this system. An integrated system is particularly suitable if you are building or re-roofing a property. If your roof does not need replacing, a framed system can be installed. This type of system is made up of a number of standard solar panels that fit into a frame which is then attached to your existing roof. These systems are neat, unobtrusive and can be fitted on flat or sloped roofs or even mounted on the ground.

What does this mean to me?
Every unit of electricity you produce reduces the amount of electricity bought from your energy supplier and therefore the amount of carbon dioxide released into the atmosphere. Currently domestic use is one of the highest users of electrical energy in the United Kingdom.

The electricity you currently buy from your energy supplier is sold to you in electrical units called kilowatts. Some suppliers may charge you less for units you consume during the night and more for units used during daylight hours. An electrical unit as itemised on your electricity bill is also known as a kilowatt hour (kWh). By investing in a Solar PV system you are buying a system which produces electrical units for use in your own home and will cut the amount of electricity that you currently are purchasing.

Am I really helping to reduce carbon emissions?
A solar PV system may vary in amounts of energy it produces depending on amount of available light, positioning of the unit ( a south facing roof is best) and efficiency of other factors like wiring. As a standard measure each unit is measured in size according to the number of electrical units it would produce in an ideal environment. The smallest system size usually installed on a domestic property is 1 kilowatt peak (kWp). In the UK, a 1 kWp system is expected to produce at least 750 electrical units -kilowatt hours - every year. The average household in the UK uses approximately 3,300 kWh every year. Therefore a 2 kWp system will produce nearly half of your yearly requirements and avoid around 650 kilograms of carbon dioxide emissions. With a life span of at least 25 years, a 2 kWp system will generate around 37,500 kWh and avoid approximately 16 tonnes of carbon dioxide emissions in its lifetime - enough to fill three hot air balloons.

What type of system should I buy?
The size and type of system suitable for your property depends on many factors including available roof area and your budget. Producing electricity directly on your property no matter how much will obviousley benefit you in the long run. With very low transmission losses, clean electricity will continue to be generated efficiently and reliably. It will help protect you from rising energy prices, protect the environment from carbon emissions and prove a sound investment.

As a rule of thumb You should try matching your system to your daily electrical requirements to make best use of the electricity you generate. You may also find it beneficial to try to plan for any future electricity requirements, such as more household appliances, given that your system will continue operating for at least 25 years and electricity prices are likely to rise in that time. Alternatively you may wish at a future date to install another system like a wind turbine to increase your capacity. Do not forget some systems do require planning permission.

Some key considerations before you install Solar PV?
The ideal roof pitch is approximately 35-40 degrees or less. PV can be successfully installed on a flat roof as there is much scope for ideal orientation. However on a pitched roof in excess of 35-40 degrees the area exposed to light will be restricted and this will affect your system's performance. You will need at least 10 square meters of un-shaded, exposed roof area facing predominantly south, with a horizontal angle of up to 40 degrees. Chimneys, roof lights or nearby trees can all shade your PV and need to be taken into consideration when deciding where best to position it.

A proffesional installer will be able to advise you on the best location and can be a good reason not to go it alone and install the system yourself. If you do decide to go it alone you may want to read up on it. Here is a good resource for that purpose.

Click here for more on installing your own solar energy system

When is a system completed?
A system must be commissioned, i.e. when it has been tested and shown to be operating correctly before it can be called completed. Once the system is generating electricity, a commissioning certificate will be issued by your installer. Your solar PV system is now fully functional and contributing to your property's electricity usage.

Other planning requirements
We have already mentioned that some alternative energy systems require planning permission. It is best to check with your local authorities if you are not sure. However other instances would include if the system is attached to listed buildings or those in conservation areas. Again if you are in any doubt, check with your local planning authority.

Selling your electricity on.
By producing your own electricity you can become a supplier yourself. As well as producing electricity for your own needs, there will be times when your system produces more than you need. In this situation, the surplus electricity can be fed into the local network. It is the responsibility of your installer to ensure your system is installed according to the existing electrical installation regulations. It is also their responsibility to contact the local Distribution Network Operator to advise that a new solar PV system is being connected in their area. The connection of solar PV systems to the electricity grid has become standard procedure and paperwork will likely be dealt with by the installer as part of the service.

Other Benefits.
As well as producing your own electricity there are other benefits to be gained from your system.

Buy back schemes
Many energy supply companies offer buy back schemes. This is when they purchase the electricity you produce for a fixed rate. As a customer you can change your supply company at any time allowing you to always secure the best deal for the purchase and sale of your electricity.

Registering for Renewable Obligation Certificates
You can also register as an independent energy generator and sell your own electricity in the form of Renewable Obligation Certificates (ROCs) to the Gas and Electricity Markets Authority, OFGEM. This is over and above the amount that you sell the unit for. Suppliers in the U.K. are required to obtain at least 10% of their electricity from renewable resources they can do this by purchasing ROC's or else face large fines. One ROC is equal to 1000 kWh or electrical units. Therefore, on average, for every 1 kWp you have installed you are generating sufficient electricity for one ROC. The ROC system will remain in place until 2027, which provides further security to those deciding to invest now in renewables. For more information on buy back schemes or registering as an electricity generator visit www.ofgem.gov.uk.

If you want to find out more about renewable energy go to www.easy-solar-energy.com