Solar thermal heating for domestic hot water is the fastest growing renewable technology across Europe. Using radiation from the sun, a sophisticated solar collector is used to transfer the maximum amount of energy possible in to a fluid which runs through the collector and which is then used to indirectly heat water in a storage cylinder.
As solar thermal technology does not rely on sunlight but on solar radiation, it can work as efficiently in our climate to provide around 50-70% of annual domestic hot water requirements.
Using the sun as a renewable energy source helps the environment, leads to reduced energy bills and means less reliance on gas and electricity for water heating.
Basics of Solar Power
What is a solar cell and how does solar power work? Here you will find a simple introduction to the technology for the uninitiated.
What is a Solar Cell?
A solar cell or photovoltaic cell is a device which generates electricity directly from visible light by means of the photovoltaic effect. In order to generate useful power, it is necessary to connect a number of cells together to form a solar panel, also known as a photovoltaic module. . The nominal output voltage of a solar panel is usually 12 Volts, and they may be used singly or wired together into an array. The number and size required is determined by the available light and the amount of energy required.
Can the power be stored?
The amount of power generated by solar cells is determined by the amount of light falling on them, which is in turn determined by the weather and time of day. In the majority of cases some form of energy storage will be necessary.
It is possible to connect an array of solar panels to the mains to assist when the power required is greater than that being generated. The cost of this is offset by selling surplus power back to the electricity company when it is available.
This site, however, is concerned with self-contained systems where this is not possible. In this type of system the usual choice for energy storage is the lead-acid battery. The number and type of batteries is dependent on the amount of energy storage needed.
Power Control
No matter what, sometimes there will be too much power. Other times there won't be enough. The battery will be damaged if it is allowed to be overcharged or over discharged, so a controller is needed to protect it.
The smallest systems may have only a few 12 Volt lights, but in bigger systems 230 Volts will probably be needed. An inverter is used to transform the low voltage DC generated by the solar panels into mains voltage AC.
Rationalising your energy usage is the next step to building a successful solar powered system.
