Solar panels are a way of transferring the suns solar energy into electrical energy. Although there are many different types, these most commonly come in Monocrystaline modules made up of 36 separate circuits, wired in a parallel.
The amount of power produced by a solar panel is incredibly dependent on the weather. When beams of light, known as direct radiation means the solar panel can produce up to 80% more power than if the weather is cloudy, meaning the solar panel only receives diffuse radiation. Typically it should be expected for the efficiency of a solar panel to be around 14% -16%,
Shading is a serious factor when considering the installation of solar panels. Anything from a building to an Arial cable casting a shadow on a solar panel can cause it to nearly completely stop working. This is because of the electrical circuit in each module. Each module has 2 circuits running in parallel, which splits the module up into 2. If a shadow is cast upon one of these sides, it provides immense resistance and breaks the circuit, deeming the entire half panel useless. This can happen to both sides of a panel, even with the smallest of shadows. To prevent this from happening the solar panels must be positioned so that they never encounter shading. This means a detailed site investigation must be done around the site to make sure there are no building, trees or any other objects shade the panels. Furthermore, there are many different types of software that can produce solar models, with information on where the sun will go all through the year, and where it will shade. Solar calculators can be used to see how efficient the location of the solar panel is.
The hotter a solar panel gets, the lower its efficiency gets. This is because as the electrical mechanism gets warmer, so does the resistance, resulting in the currant increasing and the voltage decreasing which decreases the power output. The most effective panels are offset from the rood so there is air circulation around the whole panel. However, this means wind can get underneath and could blow the panel away. Typically, a meter of plain roof is left to help prevent this from happening, with extra strong fixings used.
Due to the sun rising in the east and setting in the west, for a static panel, it is most efficient to face it towards the south, at an angle similar to that of an average roof, which is about 35 degrees. However, panels can be put of a mechanical system that moves each panel in accordance with the sun. At the CAT centre in Wales, tests are currently being done to see if it is more efficient to have a static panel, a panel that follows the suns path, a panel that moves from east to west, and a panel that points to where it is lightest in the sky. It would be valuable to see what the results are to see if it can be incorporated within the school project.
An issue with solar panels is space. The best place for them to be positioned is on a roof, as it is out the way. However, this can complicate plans to have a green roof, or use solar thermal water heating, as well as having a roof garden. Calculations and research must be done to work out which system would have the most sustainable and positive effect for the school.
A school, especially a large multi-storey school like this given design, will use a lot of electricity. There is likely to be hundreds of computers, TVs, lights, speakers, kitchen utilities and other appliances a typical school has. A typical computer runs at about 850watts, which would need a whole solar panel that runs at 1.75kw (peak) to power it. In addition, solar panels only work when the sun is out, so at night especially another source of electricity must be used.
Because of the small power output of a solar panel, and the large usage of computers, it is in-practicable to consider using solar panels as the main electricity supply, as it would not cope with the schools usage. However, it is certainly a possibility to use solar panels to power the lighting, and maybe some appliances in the school.
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