In a survey it was estimated that over 80% of UK farms would have solar PV systems installed on their open-top outbuilding roofs by 2013 with some even installed on angled brackets on available space on their farmland. About 20% would consider leasing their land for the latter which would be considered an approach suitable for a large-scale solar farm. In either case, the solar installation is being used to generate electrical power to as a generation income model that will benefit from government subsidies in the form of the Feed-in Tariff (FIT) Scheme
The space required for a mid-sized solar PV farm roof installation is around 400-500 square metres. A typical 60kWp (kilowatt peak) system producing 51,000 units of electricity a year would meet most on-site demands of an average farm and cost in the region of £170,000-£200,000. Roof mounted schemes are more popular because they use existing surface area that is not currently adding value to the business rather than land that could be used for food production. Ideally, the roof should be South facing and tilted at 30-50degrees, which most farm roofs are not but it is unlikely to result in significant reduction in performance.
Through the FITs scheme, farmers could earn around £16,000 income a year, plus save nearly £2,000 in electricity bills. However, there is a sense of urgency as the Government is currently conducting a review of the FITs scheme to prevent larger projects of more than 50kW capacity from taking the lion’s share of the £360m budget.
Farmers are well placed to benefit from solar PV systems because of the large amount of roof space available on farm buildings and their situation in open spaces reducing problems of shade. Although most new PV technologies are developed to be effective even on cloudy days, if shaded (even partly) performance will be greatly reduced.
The kWp of a solar PV system is the value of power generated under full solar radiation – at noon on a sunny day, for example. It is defined as 1000 watts per square metre. In the UK, a 1kWp system will generate around 750kWh per annum. The benefits of solar PV system are dependent upon how many kWh it can generate per kWp. To be eligible to benefit from the FITs scheme, systems connected to the grid have to be accredited under the Microgeneration Certification Scheme and so does the installer. Installations greater than 50kW capacity must be accredited to Ofgem via the Renewables Obligation process).
Grid connected systems allow you to use some of the electricity you generate with the rest being fed directly into the National Grid. By so doing, you are guaranteed an extra 3p/kWh (export tariff), although it may be possible to negotiate higher rates depending upon your supplier. A generation meter would be required and this would monitor the total amount produced and how much is exported and how much is used locally. You have to have one of these if your installation capacity is greater than 30kW.
One of the most high-profile, large scale, private solar power plants was officially launched to the world by Glastonbury festival king, Michael Eavis, in November 2010. 1,116 solar PV panels were installed on the roof of his cow shed (nicknamed The Mootel) at Worthy Farm, site of the annual Glastonbury festival. The installation is used to meet a proportion of the festival’s annual energy needs (which on a busy night amounts to 15 megawatts of power) and generates enough electricity to power 40 homes annually, although it will all be used privately by the site or fed back into the grid to generate a renewable power system income of around £60,000 a year.