The placement of solar panels on your property can be the difference between generating a little and a lot of energy. Solar panel installers can survey your home to find the right location, but maybe you just want to quickly get this answer without having to hire anyone.
The Solar Panel Suitability Checker by Solar Panels UK is a free app that lets home or business owners find the best spot on their property or building's roof for solar panels by simply clicking the "use current location" button. The app uses the iPhone's GPS to zoom in on your home with Google Maps and then uses a performance graph overlay to show the zones where solar panels would perform best or if they would be suitable at all.
The app only gives general suitability information right now, but as CleanTechnica reports, the company is already working on a second release that would incorporate sun time data based on your GPS location and the slope of your roof to give the estimated kWh of energy generation for each zone. That's a lot of useful information for free.