Virginia Debates Impacts of Solar Panels on Stormwater Runoff | Climate change

The new director of Virginia’s top environmental agency seemed to be stating the obvious when he told a conference in late March that “water doesn’t go through” solar panels.

But his statement that solar panels should be regulated as impermeable surfaces — followed by a memo from the agency that the new policy would take effect immediately — signaled a major policy pivot. It also sent jolts to the solar industry, which quickly erected power generation facilities across the state to meet state and private company renewable energy goals.






Solar panels are erected on a field in Campbell County, Virginia in March 2021. (Kipp Teague/CC BY-NC-ND 2.0)


Two weeks later, on April 14, the Virginia Department of Environmental Quality responded to industry concerns in a second memo. The agency said it would give projects more time to comply and said stakeholder feedback would be considered in shaping how the policy will be enforced.

Typical examples of impermeable surfaces are roads, parking lots and roofs. These types of land cover prevent water from seeping into the ground as it would through a natural surface. When rain falls, more of it runs off these hardened surfaces and at higher speeds, causing erosion and carrying pollutants into waterways. Polluted stormwater is a major problem for the Chesapeake Bay and its rivers.

Regulating solar panels as waterproof can be complicated.

“The way it was presented was like it was a decided science. I don’t think the industry would agree with that,” said Harry Godfrey, executive director of Virginia Advanced Energy Economy, a coalition of businesses seeking affordable clean energy. “To treat ground-mounted solar panels, for runoff purposes, like you’re treating a new road or a big-box store, hydrology just doesn’t work that way.”

Many states have chosen to regulate panels as permeable. They say the volume and rate of runoff the panels contribute to is somewhere between farmland and parking lots and is highly dependent on the type of ground cover under the panels. Additionally, agencies have been tasked, often by state legislatures, to regulate the solar industry in a more holistic way that considers its potential to help wean localities off fossil fuel-based energy sources. .

As one green building lawyer put it, referring to Maryland’s position on solar panels, these states “are not trying to change the laws of science, but rather seek through public policy to give priority to environmental stewardship”.

Mike Tidwell, director of the Chesapeake Climate Action Network, said he viewed the change in solar panel regulations in Virginia as an insult to the state’s renewable energy sector. And he said it’s especially problematic for Northern Virginia’s data center epicenter for companies like Amazon and Google, which have doubled their 100% renewable energy commitments.

“I think the [Gov. Glenn] The Youngkin administration is out of step, and that will have practical economic consequences for the state,” he said.

Youngkin appeared alongside Google officials in Reston on April 19 as the company announced plans to invest an additional $300 million in Virginia this year. A Google blog the same week said the company plans to run all of its facilities with “carbon-free energy” by 2030. Amazon also announced plans to power its operations with 100% renewable energy from 2025.

Virginia has already taken a similar approach to other states on solar panels. The Virginia Department of Environmental Quality’s past practice was to consider only solar panel support posts and beams, which connect to the ground, as impermeable areas, the March 29 memo said.

“However,” the memo continues, “this approach has the potential to underestimate the volume or rate of post-development runoff from solar arrays, which in turn has the potential to negatively impact watercourses or downstream properties”.

DEQ director Mike Rolband had a nearly 40-year career in resource protection before Youngkin appointed him to the post earlier this year. He laid out some of the stormwater issues he says have been associated with solar development during remarks at the Environmental Symposium in Virginia on March 29, the day the memo was released.

“There are all kinds of issues with runoff from solar installations,” he said. “The fundamental problem is that for several years a decision has been made that solar panels are permeable. This is a problem for people downstream [because] it does not follow erosion and sedimentation protocols. It hurts people, and we want to fix it.

Solar panel operations in the state have been cited for stormwater violations, but some say those cases don’t represent the majority and using best practices can prevent them.

In 2018, heavy rains spurted muddy water from the grounds of a new 200-acre solar panel project in Essex County and into Muddy Gut Creek, a tributary of the Rappahannock River.

A local TV station headlined “Green Solar Farm Turns Essex County Watershed Brown”, with video of murky water flooding part of a road and residents appalled by the runoff. DEQ later fined the Essex Solar Center and the company behind the project $245,000 for violating stormwater and erosion control laws as part of the a decree of consent.

Even in a well-managed solar installation, there is some debate as to whether the panels have a significant effect on runoff volumes.

A 2011 study by the American Society of Civil Engineers found that solar panels have no significant effect on runoff volumes as long as certain ground covers and buffer strips are in place. If the ground under the panels is bare or covered with gravel instead of grass, this would increase the need for stormwater management.

“The kinetic energy of flow flowing from the panels was found to be greater than that of precipitation, which could cause erosion at the base of the panels,” the study found.

The solar industry has a working group that researches best practices to reduce the impacts of stormwater on installations. As it stands, DEQ’s policy change could require solar installations to acquire 20% more land for projects to offset impervious surfaces, which would have “a significant impact”, David Murray said, Director of Solar Policy for American Clean Power.

DEQ’s first memo indicates that the state’s federal program for the bay also considers solar arrays as impervious areas for the purposes of water quality modeling as part of the Chesapeake Cleanup Plan. This means, as Rolband put it, “the rest of Virginia will have to compensate” for their extra runoff.

Bay Program spokeswoman Rachel Felver confirmed that for modeling purposes, solar panels are considered “impermeable, building and otherwise” in current land use data. In Virginia they are reported as “unconnected” waterproof to account for spacing between panels.

“However, impermeable land use does not specifically model solar arrays, and we are still trying to understand how states are reporting stormwater management actions and practices associated with solar farms,” she wrote in an email.

Program modellers plan to discuss these inputs further at a technical working group meeting in early May.

Maryland, Pennsylvania, and New Jersey have policies that consider solar panels permeable under most conditions or exempt panels from being considered impermeable for stormwater management purposes.