Solar energy is plentiful and essential for life here on earth. The sun is 1 million times bigger than planet earth and by far the biggest source of energy available to us today. In fact, if the human race used only solar energy for all its energy needs (assuming 100% absorption of solar radiation) it would only take 88 minutes of solar radiation to meet our total energy requirements for a whole year!
Solar energy is renewable and clean and there are a number of ways we can harness it for use in our homes and buildings, naturally maximising the solar gain or generating our own energy using solar thermal or photovoltaic (PV) panels.
Most frequent in Passivhaus design, considering the orientation and design of new buildings and the window positioning can maximise the benefits of solar gain for heating, using direct sunlight during the winter months as a baseload.
Solar PV panels convert light into electricity due to the photovoltaic effect. This is when sunlight (photons) causes the electrons within a certain material to move, generating an electric field to be harnessed. The energy from the solar radiation is carried by the photons and transferred to the electrons within a silicon material, it is this input of energy to the electrons which causes them to become excited. The excitation causes the electrons to break free from their parent material and travel between positive (p) and negative (n) semi-conductive zones within the PV cell. It is the movement of the electrons between the p-n zones which generates an electric current to then be harnessed.
Solar Panels can also be used for heating and hot water, where instead of an electrical process happening due to a process caused by sunlight, the panels directly absorb the heat omitted by the sun transferring it through a heat exchanger to the thermal store - most commonly an accumulator tank.
Alternatively, the electricity provided by solar PV can be used to supply an electric emmersion heater within a hot water accumulator tank.