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Clean Power

Published on September 3rd, 2020 | by Tina Casey

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Why Is Everybody Suddenly Talking About The World’s Largest Solar Tree?

The Intertubes have been practically ablaze with talk of the world’s largest solar tree, recently unveiled by the CSIR Central Mechanical Engineering Research Institute in India. The gizmo certainly looks stunning, festooned as it is with 35 solar panels branching out from a central tower. However, looks are not everything, and now the question is whether or not CSIR-CMERI will find takers for their new invention.

solar trees farming sustainable

Everybody is talking about solar trees because they fit right in with the emerging solar-plus-farming model (photo courtesy of Ministry of Science and Technology).

A Solar Tree For Fossil-Free Farmers

For part of the answer to that question, we turn to CSIR-CMERI and the Ministry of Science and Technology, which issued a press release about the new solar tree last month.

“The installed capacity of the Solar Tree is above 11.5 kWp [kilowatts peak]. It has the annual capacity to generate 12,000-14,000 units of Clean and Green Power,” said CSIR-CMERI Director Harish Hirani.

That doesn’t sound like much to write home about, but then again, the solar tree is aimed squarely at the market for solar energy in the agricultural sector, and it is tailored to the needs of farmers in India.

“The Solar Trees were designed in a manner to ensure minimum Shadow Area, thus potentially making these Solar Trees available for widespread usage in Agricultural activities such as High Capacity Pumps, e-Tractors and e-Power Tillers,” explained the Ministry of Science and Technology.

In other words, the farmer loses a minimum of arable land (more on that in a sec), while avoiding the cost and volatility of fossil fuels.

In addition, the new solar tree is designed to be grid-connected, potentially enabling farmers to generate income by shunting off any excess energy.

We’re thinking a storage component would gild the clean power lily, so that may be forthcoming.

Solar Trees For EV Charging, Maybe

Considering the small footprint of the solar tree relative to its striking design, the concept may also find a home at any number of businesses looking to burnish their green brand.

In particular, we’re thinking that solar trees would make an eye-catching complement to electric vehicle charging stations at company parking lots and corporate campuses.

Ford tried something along those lines back in 2014, though that effort involved micro wind turbines at EV charging stations.

As for solar trees and EV charging, looking at you GM. The company just inked a deal with the fast-charging specialist EVgo for 2,700 public EV charging stations deploying solar power.

Come to think of it, the convenience store sector could be another area of opportunity. For example, BP is installing battery-boosted EV charging stations at  ampm stores in five US states, and there are many thousands more locations in that line of business.

The solar tree design could also be a good fit for off-grid EV charging locations where a minimal footprint is required for environmental or logistical reasons.

Solar Panels & Farms Can Co-Exist

Circling back around to agricultural applications, there is plenty of buzz afoot in the US and elsewhere about the loss of farmland due to solar development.

The new solar tree could help mitigate those impacts, at least on a relatively small scale. According to CSIR-CMERI, the solar tree consumes just 1% of the land compared to a conventional solar array, while providing for 100 times more solar power.

That’s all well and good as far as the ground footprint goes, but the shade footprint is another matter.

The solar tree is engineered to minimize shade by allowing for plenty of space between the solar panels, so that should help conserve more land for growing crops between and under the trees.

Also helping matters along would be further developments in the field of agrivoltaics, in which shade-tolerant crops are grown in and among solar panels.

Here in the US, most of the activity has focused on mixing solar arrays with grazing areas for livestock, or creating pollinator habitats.

Food crops have been a bit slower on the uptake. However, momentum is building for accelerating the farm-to-lightbulb pipeline, partly because researchers in the regenerative agriculture field are beginning to quantify the advantages of solar panels for soil and water conservation.

More Solar Trees For More Solar Farmers

So, how far along is this solar-plus-farming movement? Pretty far, it seems. Speaking of BP, the company recently bought a big stake in the Tennessee solar developer Silicon Ranch, which is already offering a “Regenerative Energy” package for farmers.

Here, let’s have Silicon Ranch explain:

Regenerative Energy™ is an outcome-driven, verified, certified product that combines clean electricity generation with carbon sequestration, ecosystem restoration, and rural revitalization. Regenerative Energy™ projects are built and operated in alignment with natural systems and approach solar farming holistically. A transformative new standard of excellence for the solar industry, Regenerative Energy™ aims to improve the way the solar industry manages land by normalizing regenerative agriculture practices on solar farm sites.”

Got all that? Good! The basic idea is partly that shade from solar panels reduces evaporation, enabling soil to retain more moisture. In addition, the crops underneath can provide a cooling microclimate that helps boost solar cell efficiency.

Another part of the equation is that ground-mounted solar arrays will take cropland out of circulation, but not forever. Farmers looking at long term land preservation can dedicate part of their acreage to solar panels on a rotating basis, giving the soil a chance to rest and replenish.

The Food-Water-[Solar] Energy Nexus

Here in the US, the National Renewable Energy Laboratory is a fan. Last year NREL researchers published the results of a solar-plus-farming study in the journal Nature Sustainability.

Though relatively limited in scope, the study yielded some promising results for farmers working in dryland conditions.

“The reduction in direct sunlight exposure beneath the PV panels led to cooler air temperatures during the day and warmer temperatures at night, which allowed the plants under the solar arrays to retain more moisture than the control crops that grew in open-sky planting areas,” the researchers noted.

Among the findings for plant growth:

  • Total chiltepin [a type of pepper] fruit production was three times greater in the agrivoltaic system compared to the control.
  • Water-use efficiency for the jalapeño was 157% greater in the agrivoltaic system.
  • For the cherry tomato, water-use efficiency was 65% greater and total fruit production doubled in the agrivoltaic system.

“The co-location of PV and agriculture could offer win-win outcomes across many sectors, increasing crop production, reducing water loss, and improving the efficiency of PV arrays,” the researchers enthused. “Adopting such synergistic paths forward can help build resilient food-production and energy-generation systems.”

The CSIR-CMERI solar tree fits right into this model. The NREL study also indicates that the CSIR-CMERI engineers could potentially increase the surface area of their solar panels while still enabling farming to take place under their solar trees.

We’ll see about that. Meanwhile, the NREL findings could help provide US farmers with more leverage to take advantage of revenue-generating solar panels. That lifeline is important now more than ever as the COVID-19 outbreak has increased the ongoing stress of keeping a small farm afloat.

Keep an eye on New Jersey, where things are waxing hot and heavy over new state legislation that could blanket the state with utility-scale solar arrays.

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Photo: Solar Tree courtesy of Ministry of Science and Technology.

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About the Author

specializes in military and corporate sustainability, advanced technology, emerging materials, biofuels, and water and wastewater issues. Tina’s articles are reposted frequently on Reuters, Scientific American, and many other sites. Views expressed are her own. Follow her on Twitter @TinaMCasey and Google+.



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