- Many solar parks in Tamil Nadu are relying on glyphosate-based herbicides for vegetation control, raising concerns about long-term health effects, groundwater contamination, and air pollution.
- Clearing the vegetation entirely contributes to the heat island effect, while sustainable practices such as solar grazing, weed-cutting machines, and agrivoltaics offer viable alternatives.
- Experts stress the need for stricter regulations to address the environmental and health risks of unregulated herbicide use in solar parks.
When a 40-acre solar park came up in Tamil Nadu’s Tiruppur district last year, residents of a colony bordering the solar park, were unaware of the potential consequences. Now, they are increasingly troubled by the strong smell and possible health risks of herbicides that the park is using for weed control.
“We smell the herbicide on spraying days and notice it every month. Even last month, the smell lingered. We have seen one of our locals in the village spraying herbicides in the park periodically to control weeds,” Vanathi, 45, a resident of Nallamapuram Colony, said, raising concerns about their effects on health and the environment. “We fear these chemicals will seep into our water. The effects may not be visible now, but we worry about lasting damage they could cause in the future,” said Vanathi. Her name has been changed to protect her identity.
Vanathi says the impact may be less severe indoors but the children who play outdoors could come in direct contact with chemicals as the solar park, located in in Kuttapalayam village near Kangayam town, is separated from the colony by just a steel-wire fence.
Karthikeya Sivasenapathy, whose Senaapathy Kangayam Cattle Research Foundation shares a border with the solar park, said, “When agricultural or grazing lands are converted into solar parks, glyphosate-based herbicides are often sprayed recklessly to control weeds beneath the panels, with no regulations or limitations in place.” Sivasenapathy, who is also the Secretary of the Environmental Wing of the ruling Dravida Munnetra Kazhagam (DMK) party, said that the environment wing of DMK has already highlighted the dangers of glyphosate use in solar farms through a letter to the state and central government, in September 2024, urging immediate intervention and safer alternatives.
The unorganised sectors often rely on herbicides to minimise maintenance costs, given the 25-year lifespan of solar parks,” said R. Chellappan, Founder and Managing Director of Swelect Energy System Limited, a solar power company. He said that Swelect Energy System Limited strongly opposes the use of herbicides or chemicals for clearing vegetation in solar parks due to environmental concerns. “We ensure that vegetation under our solar parks is removed solely through mechanical methods to prevent pollution.
A spinning mill owner in Tiruppur admitted to using herbicides in their solar farm to control vegetation beneath the panels. However, after applying the chemicals, they found that the vegetation dried out completely, causing increased sand and dust accumulation on the panels from the barren land, which reduced panel efficiency and made cleaning more intensive. Now, they have switched to mechanical clearing, allowing vegetation to grow to a minimal height without shading the panels. “However, some solar farms that we know have found it infeasible to regularly maintain vegetation. As a result, they have opted for automated panel cleaning, ensuring that there is no vegetation below and minimising dust accumulation,” they further said, on the condition of anonymity as it can harm their company’s reputation.
Mongabay India reached out to the land owner of the solar park in Kuttapalayam village, but there was no response.
A fear of long-term impact
As Tamil Nadu rapidly expands its solar energy footprint, a silent threat is taking root beneath the panels — one that could jeopardise public health and local ecosystems, experts said. The unchecked use of herbicides for vegetation control in solar parks is raising alarms among communities, who fear that the long-term consequences of the practice may outweigh the benefits of clean energy.
Tamil Nadu has aggressively expanded its solar energy capacity, ranking third in India for installed renewable energy and fourth for solar capacity, as per a state government report. Solar generation surged 53% in three years, from 7,203.11 million units (MU) in 2021–22 to 11,033 MU in 2023–24. However, as solar parks continue to spread across the state, the concerns surrounding their maintenance practices are intensifying.
Sivasenapathy, from the ruling party in the state, pointed out that around 70 houses with at least 300 residents in the Nallapuram Colony live next to the solar park, completely unprotected from the effects of herbicides. He raised concerns about nearby water bodies, “Runoff from the solar park flows into the nearest stream, a lifeline for humans, cattle, and other life forms. How can we undo the damage once it’s done?”
A.D. Dileep Kumar, CEO of Pesticide Action Network India, warned, “The volatile components of these herbicides could evaporate into the air, especially with rising temperatures due to climate change. Wind drift can carry these contaminants over long distances, polluting food, water, air, and entire ecosystems.”
“Even at low levels, contamination can cause chronic illnesses that are difficult to cure. The toxins gradually accumulate in the body, acting like slow poisoning,” Dileep Kumar warned while cautioning that herbicide runoff from solar parks could contaminate dam water, which supplies both local and urban residents, contaminating far-off places. While weedicides are seen as cost-effective, chemicals like glyphosate—classified as probably carcinogenic to human health—pose long-term health risks that are often overlooked and far outweigh short-term savings. “If you consider the long-term adverse impact, their use is not economical,” Dileep Kumar added.
Lack of government intervention
Over 74% of solar farms in India are built on land that affects biodiversity and food security. This includes 67.6% agricultural land, of which 38.6% suitable for seasonal crops and 28.95% for plantations or orchards. Additionally, 6.99% comprises natural habitats, such as evergreen, deciduous, and swamp forests, which hold significant biodiversity value.
Sundar Rajan, an environmental activist and member of Poovulagin Nanbargal, an environmental organisation in Tamil Nadu, highlighted that while solar energy is seen as a green initiative, it is not currently required to undergo environmental impact assessments (EIA) or follow an environmental management plan. He argued that these projects should be included in the EIA process to ensure compliance with biodiversity and pollution control laws.
Sivasenapathy cautioned that the situation could lead to another endosulfan-like tragedy, similar to what happened in Kerala, where unchecked pesticide use caused severe health issues, including birth defects before it was eventually banned.
Safer alternatives to herbicides
Environmentalists argue that alternative vegetation control methods should be prioritised. “Earlier, they hired around ten of us for weed removal, which provided some income, but now they’ve switched to a single worker who just sprays chemicals,” said Durga (name changed).
Dileep Kumar suggested that while manual removal may be tedious or expensive, using weed-cutting machines could offer a sustainable solution. “By employing these machines, solar parks can manage weeds without chemical contamination,” he noted.
One successful alternative is solar grazing, where livestock such as goats control vegetation. Sulochana Cotton Spinning Mills in Palladam, which operates entirely on renewable energy—94% from wind and 6% from solar—has a ground-mounted solar park with a capacity of four MW. Starting with 40 goats eight years ago, the herd has expanded to 360, replacing their entire need for grass cutters. “We are committed to conserving every bit of energy, even the small amounts consumed by grass cutters,” remarked R Sabhari Girish, Head of Sustainability of the Mills.
Chellappan further emphasised that similar to developed countries where solar panels are designed at a height to allow grazing, India should adopt a similar vision and move towards such sustainable practices.
Martin Scherfler, Co- Founder and executive director, Auroville Consulting, appreciated the approach of solar grazing on the vegetation beneath and around the panels, which creates a mutually beneficial system that naturally controls plant growth while reducing the need for manual or mechanical vegetation management. “When implemented sustainably, solar grazing can even help restore degraded lands,” he stated. Auroville Consulting is a sustainability organisation in Tamil Nadu specialising in policy advocacy, renewable energy, and ecological planning.
On the other hand, Dileep Kumar noted that barren soil without vegetation absorbs more heat, contributing to the heat island effect. Scherfler explained that vegetation naturally cools the environment through evapotranspiration, helping to lower panel temperatures and enhance efficiency.
“The efficiency of solar panels typically decreases with increasing temperature rather than increasing. By maintaining a cooler microclimate through vegetation, the overall system performance can be improved,” he added.
A scientific report published in 2021 indicated that in many countries, it is common practice to clear vegetation and use herbicides to prevent regrowth in solar parks, increasing emissions from land-use change (LUC). The report further highlights If all vegetation in designated solar park areas in India is permanently removed, the resulting LUC emissions from 2020 to 2050 would account for 2.5–3.5% of the total emissions produced by burning natural gas for electricity generation in the same period.
A growing trend in the renewable energy sector is agrivoltaics—the integration of agriculture with solar energy. “In this system, solar PV panels are typically elevated on stilts, and panel rows are spaced wider apart to allow sufficient sunlight for crops growing beneath them. In some cases, crops are cultivated in the interspaces between solar module rows, optimising land use,” explained Scherfler.
Pointing to the example of agrivoltaics in the world’s first solar-powered airport, Cochin International Airport, Dileep Kumar noted that the airport still grows vegetables beneath its solar panels. “This demonstrates how land can be used more effectively, creating additional income for the solar park owner. We should also place more emphasis on rooftop solar installations, reducing our dependence on land-based solar parks whenever possible,” said Dileep.
“Beyond operational benefits, vegetation under solar panels enhances soil health by improving soil carbon content and fertility, supporting better stormwater management, and preventing soil erosion,” Scherfler noted. Additionally, he stated that it contributes to biodiversity conservation by providing habitats for pollinators and other wildlife, further strengthening the ecological value of solar installations.
As a way forward, Dileep Kumar emphasised that biodiversity management committees at the local government level could intervene in this issue, sensitising both the government and the public. However, government institutions and legislation seem to be silently, or perhaps purposefully, supporting the continued use of these herbicides, he added.
Read more: As renewable sector grows, need for regulating it comes to the fore
Banner image: Goats graze beneath solar panels at Sulcohana Cotton Mills’ four MW solar park, reducing the need for herbicides and conserving energy used for grass cutting. Image courtesy of Sulochana Cotton Mills.
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