A new study finds that houses within a half-mile of a utility-scale solar farm have resale prices that are, on average, 1.5 percent less than houses that are just a little farther away.

The research from Lawrence Berkeley National Laboratory helps to refute some of the assertions of solar opponents who stoke resistance to projects with talk of huge drops in property values. But it also drives a hole through the argument made by people in the solar industry who say there is no clear connection between solar and a drop in values.

The authors analyzed 1.8 million home sales near solar farms in six states and found diminished property values in Minnesota (4 percent), North Carolina (5.8 percent), and New Jersey (5.6 percent). The three other states—California, Connecticut, and Massachusetts—had price changes that were within their margins of error, which means the price effects were too close to zero to be meaningful. The paper was published in the journal Energy Policy.

The authors accounted for differences in property features, inflation, and other factors in order to isolate the effect of proximity to solar.

Ben Hoen, a co-author and research scientist at the Lawrence Berkeley lab, said the numbers are clear but additional research is needed to understand what’s happening on the local level to lead to these price effects.

“We have a sense of the ‘what,’ but we don’t know the ‘why,’” he said.

For example, he doesn’t have a thorough explanation for why the price differences are higher in some states than others.

The researchers chose this group of states because they were, except for Connecticut, the top five in the country for the number of solar installations of at least 1 megawatt as of 2019. They included Connecticut because it is an example of a state with a high population density near solar projects.

Hoen emphasized that the results show a period in time, with transactions that occurred from 2003 to 2020, and may not reflect prices right now.

Also, he noted that the paper’s analysis doesn’t take into account any of the financial benefits of solar for landowners and communities, which may include payments from the developer and a decrease in local taxes.

The study is being released at a time of rapid expansion in the number and size of solar projects, which is a key part of the country’s push to reduce the emissions that contribute to climate change.

The scale of growth in solar development has been met with an intensifying resistance in local communities where some people argue that the projects are ugly and pose a threat to property values and human health. Solar opponents amplify these concerns on social media.

Of all the arguments against solar, the idea that it will hurt property values has been among the most potent, based on prior reporting by Inside Climate News about the local debates. At public hearings and in comments filed with regulators, some residents talk about how they fear reductions of 40 percent or more.

This story originally appeared on Inside Climate News.