Googler Carl Elkin has been working on a particularly interesting 20 per cent project that leverages the power of Google Maps and Google Earth. Project Sunroof can tell, based on your address, if it's worth getting solar panels installed on your house.

It uses high-resolution aerial mapping (the kind Google Earth uses) to gauge the solar energy potential of your roof. Based on your address, Project Sunroof can estimate the hours of available sunlight per year and the square footage available for solar panels. It also provides an estimate of net savings.

This is currently being tested in the San Francisco Bay Area, Fresno, central California, and the greater Boston area where Google Earth has detailed imagery of the rooftops of individual houses. It's a clever idea but one that will require more high-quality aerial maps.

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