We asked Kate Vadhia, bursar of Mayfield Primary to tell us about the school's experience with photovoltaic (PV) cells, and were impressed with her enthusiasm. Mayfield had the system installed in November 2007 , after a difficult period when most of buildings had to be rebuilt after a fire. She remembered the grand opening, with parents, governors and staff sharing their delight at the prospect of reducing their carbon footprint by generating renewable energy at the school.
Other energy saving measures at the school, include lights which automatically turn on and off on a motion sensor basis and sunpipes which enable better use of natural daylight, and also windcatchers which provide climate control without the need for air conditioning http://www.monodraught.com/. The school has also reduced their heating bills by reducing the target temperature and hours of heat.
The 4 kWp PV system was provided by the solar4schools program (http://www.solar4schools.co.uk) which made use of grants from the governments Low Carbon Buildings Program (http://www.lowcarbonbuildingsphase2.org.uk/) and the Co-op Green Energy for Schools program (http://www.co-operative.coop/ethicsinaction/climatechange/climate-change-projects/green-energy-for-schools/) to buy and install PV cells from Solar Century (http://www.solarcentury.com/). This was two years ago - the package was then worth £20,000 and though grants are harder to come by these days the costs have come down too, by up to a quarter.
Mayfield was delighted to be selected and the installation was no trouble at all. A surveyor from Solar Century identified the best location, on a flat roof with little shading, and the fitting took only a day or two. Some lightning conductors had to be rearranged but that was the only cost not covered by the grants.
A real time display outside the main office shows the power being generated - on a sunny winters day we saw 720W though in May you could expect to see 5 times that - but unfortunately the sensors are still not linked into the schools IT network so this data is not available in the classrooms. If it was, then the teachers would be able to make more use of it in their lessons.
Whether or not anyone is looking the cells continue to work, silently and without maintenance. So far the cells have generated around 7200 kWh over the two years, enough to supply 3% of the school's electricity consumption. The cells have been tilted to maximise annual production, taking most advantage in the summer when the sun is high, between May and August. During the holidays the school is often busy with special events but even when it is not the electricity is not wasted, but fed into the grid.
Overall the system is no trouble at all and makes significant savings on their electricity bills. Kate told us the school is very happy with the system and would be delighted to have more.