Energy Source.. The sun, our nearest star, provides an enduring supply of light energy to our planet. Radiation from the sun provides about 100,000 TW in a year to our planet, so the energy landing on our planet from one hour of sunlight is equivalent to all the energy used by humankind here each year! On average the power radiated from the sun per square metre of the surface of our planet is about 1 kW.
Energy Capture.. Solar panels exploit a process called the photo-voltaic effect (similar to Albert Einstein's photoelectric effect) and they convert light energy into charge separation, that is voltage. A PV panel comprises two layers of crystal which are enriched so that there is an electric field across them where they join. When a packet of light energy lands, it excites an electron out of an atom in the crystal which moves according to the direction of the electric field and out of the crystal layers around the circuit. Separating the charge in this way gives rise to a voltage difference which can light a lightbulb or charge a battery.
Energy Use.. Energy can be transformed between many different forms, making it useful for all kinds of functions in schools, homes and industry. Light from the sun is transformed into electrical energy which is stored as chemical energy in batteries. This energy storage builds up during the day, so that by night it is available for us to use as electricity to run the observatory and operate the telescope and observe the sky at night!
Size.. We have eight photovoltaic panels, each one is 1.5 metres by 1 metre. With this 12 square metres of collecting area, which all directly face the sun at solar noon we collect all the energy we need for the next night of observing. This would be enough collecting area of panels to supply two UK houses for 24 hours.
Output.. The energy from our solar panels is stored in big banks of batteries. The storage capacity of these batteries is 2000 Ah at a voltage of 24V. If ever we used up all the energy stored in these batteries this would be enough energy to lift up an 8-tonne truck two kilometres in the air!
Impact.. Our solar farm is a real live demonstration that we can power our sophisticated research equipment all the time with energy collected during daytime. The students at the school see and use the result of collecting light from our nearest star and storing it so they and we can observe other stars across the Galaxy by night.