Where are the sunniest places in Minnesota?

A team of seven graduate students at the University of Minnesota has found the answer, down to the square meter.

The result is an innovative Web-based “solar suitability” tool designed to help renewable energy companies choose suitable sites for solar panels. The award-winning application also has potential uses in transportation, natural resource management and urban planning.

“It’s groundbreaking,” said Martin Morud, president and founder of TruNorth Solar, an Edina-based solar energy company, and one of the early adopters of the technology.

The application was built by students in the geographic information science (GIS) master’s program on the U’s Minneapolis campus. They started with a massive amount of 3-D aerial mapping data, then used a supercomputer to calculate solar radiation at every point in the state. Their work takes into account shade trees and tall buildings that affect a site’s solar potential, which is known as “insolation.”

On the Minnesota solar suitability analysis Web map (maps.umn.edu/solar), anyone can type in a street address for a free estimate of whether a rooftop or back yard gets enough sun for solar panels or a solar hot water system. Each point on the map is rated from poor to optimal based on the estimated amount of solar.

Morud, who installs solar arrays of all sizes, helped advise the development team, and is using the data in his business. For some commercial projects, he said, it’s possible to zoom in and select the best solar panel locations to avoid shade from rooftop air conditioning units.

“It was incredible to see a group of engineers at the U ask the question, ‘How can you utilize this?’ ” Morud said. “They had a desire to make it applicable for the industry.”

First statewide solar data

Minnesota is the first state to be entirely mapped for its solar potential, said Dan Thiede of the U’s Clean Energy Resource Team, a project that promotes energy efficiency and renewables.

Some companies, including Minnesota-based Sun Number, offer solar ratings for properties in the Twin Cities and other metropolitan areas. But Thiede said many people and institutions in greater Minnesota are interested in solar power, so he suggested the idea of a statewide solar mapping project last January to Len Kne, associate director of U-spatial, the mapping service at the university.

At the time, Kne was advising some graduate students who wanted to do a GIS project. Mapping the state’s solar potential struck a chord with them. As work got underway, Kne started calling the students the Solar Dream Team — a name that proved fitting when in July they won the $10,000 first prize in a climate app competition sponsored by Esri, the Redlands, Calif., company behind ArcGIS and other mapping technology.

“We wanted to do a project that would benefit the GIS community and the planet — and this was a perfect fit,” said Andrew Walz of Roseville, who is working on his master’s degree in GIS.

Esri founder and President Jack Dangermond, who earned a master’s degree in urban planning at the U, said his company launched the app challenge after he met with President Obama and discussed the use of mapping technology to address climate change. He said about 300 developers offered apps. A dozen became finalists.

“These kids were obviously enthusiastic about doing something that really mattered,” Dangermond said of the U solar project. “And it was a practical tool that everyone from the private sector, to government, to homeowners could actually use.”

The U team, which includes four students who just completed their master’s GIS degrees, is making the source data and programming code available free. That opens the door for researchers, government planners, utilities or energy developers to conduct analysis tailored to specific needs.

Students have been getting inquiries about other uses of the data. They include mapping roads to find sunny stretches where less road salt might be needed in winter, or studying the value of shaded stream banks in protecting cold-water-loving trout.

“These are very different uses that we didn’t expect,” said Ben Gosack, a team member who just finished his GIS master’s.

The answer to the question about the sunniest places in Minnesota is not so unexpected. Southern Minnesota, and especially the prairie farm belt, tends to be the most optimal area.

Just look at the landscape. “It is a flatter space, further south with fewer trees,” Kne said.