Essay by Eric Worrall
Farmers whose pastures are covered with solar panels have claimed an increase in wool production. But perhaps nobody has explained to farmers that if anything goes wrong their pastures could be contaminated with toxic heavy metals leached out of the solar panels, as the panels are eroded by the wind and rain.
Solar farm trial shows improved fleece on merino sheep grazed under panels
Sheep grazing under solar panels at farms in NSW’s Central West have produced better wool and more of it in the four years since the projects began, according to growers.
- Sheep grazing on solar farm trials shows an increase in wool quantity and quality
- There are calls for more research on the co-location of agriculture and renewable energy
- A NSW government review of agriculture and renewable energy has received 100 submissions
Local graziers have labelled the set-up a “complete win-win”, with the sheep helping to keep grass and weeds down so as not to obscure the panels.
In turn, the panels provided shade for the sheep and grass, and helped prevent the soil from drying out.
Wool broker Graeme Ostini, who has been grazing merino wethers at a solar farm near Parkes in a trial with the Parkes Show Society, said he had seen the benefits of running the animals under panels.
He said his sheep were slightly lighter stocked than the average in the district but were cutting an “amazing” amount of wool.
This claimed extra wool production, even if true, might come at a significant cost. According to a 2020 study, solar panels can leach dangerous heavy metal toxins, which could potentially contaminate the wool and meat produced by any sheep grazing under the panels.
Metal dissolution from end-of-life solar photovoltaics in real landfill leachate versus synthetic solutions: One-year study
Waste Management 114:351-361
Project: End-of-life Solar Photovoltaics
To investigate the after end-of-life (EoL) concerns of solar panels, four commercially available photovoltaics of 15 15cm2 size in broken and unbroken conditions were exposed to three synthetic solutions of pH 4, 7, 10 and one real municipal solid waste (MSW) landfill leachate for one-year. Encapsulant degradation and release, probability of metals exceeding their surface water limit, and change in pollution index of leachate after dumping of solar panels were investigated. Rainwater stimulating solution was found to be predominant for metal leaching from silicon-based photovoltaics, with Ag, Pb and Cr being released to 683.26 mg/L (26.9%), 23.37 mg/L (17.6%), and 14.96 mg/L (13.05%) respectively. Copper indium gallium (de) selenide (CIGS) photovoltaic was found to be least vulnerable in various conditions with negligible release of In, Mo, Se and Ga with value ranging between 0.2 and 1 mg/L (0.30%-0.74%). In contrast, minimal metals were released to MSW leachate compared to other leaching solutions for all photovoltaics. Positive correlation was observed between encapsulant release and metal dissolution with a maximum encapsulant release in silicon-based photovoltaics in rainwater conditions. Probability of exceedance of leached metals to their respective surface water limits for Al (multi and mono crystalline-silicon (c-Si)), Ag (amorphous photovoltaic) and In (CIGS) has shown the maximum exceedance of 92.31%. The regression analysis indicated that conditions of the modules and pH of the leaching solution play significant roles in the leaching of metals. The increase in leachate contamination potential after one-year of photovoltaics dumping was found to be 12.02%, 10.90%, 15.26%, 54.19% for amorphous, CIGS, mono and multi c-Si photovoltaics, respectively. Overall, the maximum metal release observed in the present study is 30% of the initial amount under the most stressful conditions, which suggests that short-term leaching studies with millimeter sized sample pieces do not represent the realistic dumping scenarios. Keywords: End-of-life, solar panel, photovoltaic, metal, leachingRead more: https://www.researchgate.net/publication/342671383_Metal_dissolution_from_end-of-life_solar_photovoltaics_in_real_landfill_leachate_versus_synthetic_solutions_One-year_study
To be fair, other studies have claimed the risk is negligible;
Potential for leaching of heavy metals and metalloids from crystalline silicon photovoltaic systems
Photovoltaics (PV) are a rapidly growing technology as global energy sectors shift towards “greener” solutions. Despite the clean energy benefits of solar power, photovoltaic panels and their structural support systems (e.g., cement) often contain several potentially toxic elements used in their construction. Determining whether these elements have the potential to leach into surrounding environments should be a research priority, as panels are already being implemented on a large scale. In this study, we analyzed soil taken from beneath photovoltaic modules to determine if they are being enriched by metals (lead, cadmium, lithium, strontium, nickel, barium, zinc, and copper) and metalloids (selenium) present in panel systems. The soil samples were collected from directly beneath c-Si photovoltaic modules and adjacent fields. Samples were analyzed by inductively coupled plasma optical emission spectrometry (ICP-OES). Selenium, strontium, lithium, nickel, and barium levels measured in soil samples increased significantly in samples closer to PV systems. There were no significant differences in lead or cadmium levels near vs. far from the PV systems. Despite concentration differences for some elements near vs. far from the panel systems, no elements were, on average, present in concentrations that would pose a risk to nearby ecosystems. PV systems thus remain a cleaner alternative to traditional energy sources, such as coal, especially during the operation of these energy production systems.Read more: https://www.researchgate.net/publication/339029474_Potential_for_leaching_of_heavy_metals_and_metalloids_from_crystalline_silicon_photovoltaic_systems
Pb (lead) and some Cr (Chromium) salts are highly toxic persistent environmental poisons. I think we all know about lead, but Chromium can also be a nasty toxin, depending on the oxidation state. Chromium (VI) salts are toxic and carcinogenic.
Maintenance could be a bigger issue than farmers realise. Simply bulldozing broken panels into the ground is not an option – according to the first study I quoted broken panels could leach up to 30% of their content of heavy metal toxins if they are buried. Even if farmers think they have a fixed price contract with the solar company, if the solar company goes bust the farmers could be left holding the baby, footing the bill for an expensive cleanup operation.
And you can bet if a farmer attempts to make an insurance claim because of contamination, every panel in their installation will receive a meticulous examination. Any unnoticed cracks and the insurance company would attempt to wriggle out of the claim, citing poor maintenance.
Frankly if I was a farmer I’d be looking at safer ways to improve profitability, than covering my land with solar panels which contain toxic heavy metals which could potentially leach into the pasture, regardless of how many assurances I had received about the alleged safety of such installations.