Dunster castle in Somerset in the UK, has been protecting Britain from the threat of invading armies for nearly 2000 years – and now, with rising sea levels posing the main threat to Britain, the castle owners have installed solar panels, so that the building can play its part in protecting Britain against climate change.

The castle is the first National Trust Grade I listed building to introduce renewable energy in this way, and the 24 photo-voltaic panels on top of the castle battlements will provide a significant source of renewable energy to the castle, the equivalent of the energy consumed by two ordinary family homes, and will reduce the castle’s carbon footprint.

Dunster Castle has set itself a three year goal of reducing the carbon footprint at the castle. Saving energy, along with reducing water consumption, increasing recycling, promoting green transport and many other initiatives, will play a crucial part in this. The PV cells themselves will generate 5,500 kilowatt-hours (kWh) per year of electricity, which will save almost 3000 kg of CO2 a year, that‘s the equivalent of traveling almost 14,000 miles in an average car.

Due to regulations that affect all historic Grade I listed buildings, the solar panels did have to sensitively installed by ensuring that the panels don't damage any part of the castle and are not visible from ground level. The design is also fully reversible, should new technologies develop in the future.

Rob Jarman, Head of Sustainability for the National Trust, said: 'The Trust is determined to severely reduce our overall use of energy and to generate our own energy needs from renewable sources on our estates. These PV panels will demonstrate how we can harness renewable energy even from hugely important conservation sites without affecting their special character'.

Other renewable energy projects by the National trust include Gibson Mill, a historic Yorkshire mill that is now powered entirely by solar panels, biomass boilers and water powered generators.