Rooftop solar: It’s contagious

Someone is considerably more likely to install solar panels on their home if others in their area have already installed them, according to new research from Yale and New York University.

The research was done by studying different clusters of solar panel installations in California from January 2001 to December 2011. The researchers found that residents are much more likely to install solar panels if they are already installed in their zip code, and particularly if they are installed on their street.

“We looked at the influence that the number of cumulative adoptions — the number of people who already installed solar panels in a zip code — had on the probability there would be a new adoption in that zip code,” said Kenneth Gillingham, the study’s co-author and assistant professor of economics at the Yale School of Forestry & Environmental Studies. “Our approach controls for a variety of other possible explanations, including clustering of environmental preferences or marketing activity.”

The results were pretty significant, just 10 extra solar installations in a zip code made it 7.8 per cent more likely that someone would install them themselves. And with just a 10 per cent increase in the number of people within a zip code to have solar installations, there will be a 54 per cent increase in the number of those going solar.

“These results provide clear evidence of a statistically and economically significant effect,” said Bryan Bollinger, the other co-author and assistant professor of marketing at New York University Stern School of Business.

The study also clearly shows what led to the increase: visibility and word-of-mouth. “If my neighbor installs a solar panel and tells me he’s saving money and he’s really excited about it, it’s likely I’ll go ahead and do the same thing,” said Gillingham. “Then there are others who’ll install because they don’t want to be one-upped by their neighbors.”

The new research was just published in the journal Marketing Science.

Clean Technica (http://s.tt/1qs36)