Electricity can be generated from the sun using "solar" photovoltaic (PV) panels. They don't have to be receiving direct sunlight in order to work - any daylight will generate electricity. However, full summer sun will generate significantly more power than an overcast day in winter and the more the panels receive, the more cost effective they will be. The panels should always be positioned to face somewhere between South East and South West to maximise sunlight received. PV panels come in a range of sizes. Incentives to invest are provided through the Feed-In Tariffs (FITs). See further below for more details.
Different Uses for PV Technology
Individual PV cells have an output of around 0.5V and are connected together to make panels, or modules, of varying sizes then used in a range of applications. Very small PV panels made up of just a few cells are used in lots of things including battery chargers, watches and calculators. Larger installations, or arrays, such as those used in a domestic setting are made up of a number of panels each capable of generating between 200-230W (depending on manufacturer and specification) connected in series. These arrays can be either 'stand alone/Off-grid' or 'grid connected'. Such systems also require an inverter to convert the electricity generated from DC (Direct Current) to 240V AC (Alternating Current).
In off-grid systems the electricity is either used directly or stored in 12Vbatteries, the more power generated then the more and the larger the batteries needed. Examples of off-grid systems include parking meters, traffic signs and outbuildings
Grid connected systems can run from as little as one kilowatt to many gigawatts in size. The maximum capacity for a domestic array that qualifies for the FITs is 4kWp. These systems can be roof mounted or free standing. For grid connected systems, bill payers will need to set up an agreement with their electricity supplier, whereby they'll earn money on all electricity generated and on that electricity exported (export tariff of 3.1p / kWh {kilowatt hour}). There is also the benefit of saving on imported electricity through using some of the PV generated power.
Cost Effectiveness
Costs for PV installations vary hugely, depending on the capacity of the system. Solar battery chargers, for example, begin at about £10, while small off-grid panels range from about £250 - £1,000. Prices for a typical domestic installation would be around £8,000, for c.20m2 of solar panels. This would generate around 2,300kWh a year, roughly two-thirds of typical domestic electricity use. The Feed-In Tariff scheme for PV installations was intended to give a return on investment of some 5 - 8% for well sited installations, giving a payback period of some 6-10 years. You should, of course, have highly energy efficient appliances and low energy lighting to minimise your power usage. Where you can sensibly do so, using appliances in the day whilst generating power is better than using them at night or in dull cloudy conditions when you would be buying in electricity .
Feed-In Tariff scheme
The government has announced another consultation on the FITs scheme which is around the need to reduce the payment for domestic systems from the present level of 43.4p/kWh for a system upto 4kWp down to 21p/kWh. the review is due to finish on 23rd December 2011 whilst the changes will affect any system not completed and registered with an energy supplier by midnight on the 11th December 2011.
The FITs scheme only rewards installations made by accredited installers of accredited products. Details are available at the website www.microgenerationcertification.org which gives details of both the accredited installers and products for a range of renewables technologies.
Investors earn an income from the FIT on every unit (kilowatt hour) of electricity generated, but also an additional 3.1p/kWh on electricity exported. Where electricity is used when the panels are generating a saving is made by not importing electricity.
Under these new proposals the payback period is likely to be around 19yrs whilst payments are guaranteed for solar PV installations for 25 years.
For further information on installers contact us directly.
Useful Contacts:
Please note that this list of organisations is not exhaustive.
The British Photovoltaic Association
Energy Saving Trust
www.energysavingtrust.org.uk/Generate-your-own-energy/Solar-electricity
Centre for Alternative Technology
