Rooftop solar: It's contagious | RenewEconomy

Rooftop solar: It’s contagious

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A new US study has found that solar power is catching – if your neighbor has rooftop panels, you’re more likely to get them, too.

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by Nathan

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 (

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  1. John D 8 years ago

    Funny thing – my neighbour ordered his panels a bit before i decided to order mine.

    It is a major argument in favour of using feed in tarifs and subsidies to get things going.

  2. McMillan 8 years ago

    Did you know that the whole quart where I live is now using some kind of solar panels? It all started after I built a diy solar panel heater using scrap metal parts and pop cans. It`s very simple, yet very powerful soalr panel, detailed diy instruction can be found here:

  3. Clive 8 years ago

    Conspicuous consumption? I think it probably also has to do with the marketing of solar panels. If an installer is installing in a neighborhood, it makes sense to market to the other occupants of the neighborhood as well. Especially seeing as you have a model home to show and talk about.

    This is all good news! Tie this to the fact that grid parity pricing is getting a lot closer in the US as electricity prices increase and I think that there should be an acceleration in PV power as there has been in other parts of the world in the next few years.

    The biggest challenge here still is the Balance of System (BoS0 Costs of installation still. This refers to the cost of installation excluding the panels. See the article for more information on the environmental benefits of installing PV solar on your roof. Saving money isn’t the only reason to go solar.

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