Sunday 23 October 2011

Is Your Roof Efficient Enough for Solar Power?

When looking at alternative ways of powering your house, you may have considered the option of installing solar panels on your roof. Some of the drawbacks are obvious: initial costs for such installations are still high (though getting lower all the time), and the collective efficiency of your roof may not be as optimal as you’d like. But how can you determine what that collective efficiency is if you don’t have the solar panels there in the first place to gauge their intake? Now, thanks to the efforts of scientists at the University of Gothenburg in Sweden, there may be a way.

By developing a GIS (graphical information system) tool — SEES (Solar Energy from Existing Structures) — the scientists are able to calculate a roof’s potential solar power collection efficiency and determine if installing costly solar panels will be of long-term benefit or burden to the people living underneath.

Researcher Fredrik Lindberg says: “The roof structures of a town may be more or less suitable for the installation of solar panels, depending on such factors as how much a particular roof is shadowed by surrounding buildings and vegetation, the gradient of the roof, and the angle of incidence of sunlight. It is now possible for the first time to determine how much solar energy a particular roof will receive during the year.”

A roof can have excellent gradient and its direction can seem perfect, but shadows cast from other sources (buildings, vegetation, flying circuses, etc.) can put a damper on the whole project; SEES can calculate how much such shade (and other variables) will detract from overall solar power collection efficiency over the course of a year. Compiling the data from a whole neighborhood’s roofs and their potential for solar power collection is child’s play for SEES. It then provides a map that lays out the neighborhood’s strongest and weakest points and determines the overall kilowatt hour value per square meter.

“We have used Gothenburg as pilot town in the project, but the method can be used in all municipalities where the necessary data is made available. The users can judge the suitability of a roof for solar voltaic panels or solar thermal panels across a wide range, based on this,” says Lindberg.

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