Bifacial Solar Panels To Open Floodgates Of Agrivoltaic Potential

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The agrivoltaic field is racing along at a rapid clip in some parts of the globe, where farmers are eager to combine renewable energy from solar panels with pollinator habitats, grazing lands, and other agricultural activities. The economic case for these dual-use projects has yet to develop in some regions, but research in Chile indicates that new bifacial solar panels could help expand the practice around the world.

Agrivoltaics & Bifacial Solar Panels

Bifacial solar panels are a relatively recent development in the solar industry. The idea is to capture diffused or reflected sunlight that hits the back of the panel, rather than only capturing solar energy on the sun-facing side.

Due to the additional energy-harvesting materials on the back side, bifacial solar panels are more expensive than their conventional solar counterparts. Researchers also need to figure out how to capture additional energy from the backside, without intruding on the efficiency of frontside materials.

Bifacial technology has the potential to provide a more efficient use of available space for generating electricity, which is an important consideration for dual-use projects. In addition, costs have been coming down as the bifacial R&D field matures (see more CleanTechnicabifacial coverage here).

The agrivoltaic connection surfaced on the CleanTechnica radar back in 2020, when we noted that the solar developer BlueWave Solar was laying plans for a dual-use, solar-plus-farming project in Grafton, Massachusetts, consisting of a new agrivoltaic array with a total of 14 acres reserved for livestock grazing and vegetable crops.

“Taking advantage of yet another twist in the farm + solar saga, the solar panels will be bifacial, meaning their back side can convert solar energy reflected from the ground,” we noted. “Researchers are already exploring ways to enhance this ‘ground albedo’ effect with different types of ground coverings, including vegetation. That could lead to additional enhancements in solar cell efficiency on farmland.”

Bifacial Agrivoltaic Arrays Can Conserve Water, Too

Agrivoltaic arrays deploy raised solar panels and other design features to enable farming activities to take place within the array. The additional cost of the raised racks is offset by the value of grazing livestock, growing crops, or cultivating pollinator habitats on the land, in addition to the broader value of preserving farmland against destructive development.

Researchers are also building evidence that the combination of solar panels and farming shares features with regenerative agriculture, a set of sustainable land management principles based on the practices of indigenous cultures. Regenerative agriculture prioritizes soil health, which solar panels can assist by reducing evaporation and reducing windblown soil loss, too. The shade from the panels also creates a microclimate that can increase yields for some crops.

That brings us to some new research on the connection between vertical bifacial solar panels, agrivoltiacs, and water conservation.

The December issue of the journal Sustainable Energy Technologies and Assessments includes a close look at the use of vertical solar panels under the title, “‌Vertical agrivoltaics and its potential for electricity production and agricultural water demand: A case study in the area of Chanco, Chile.”

You can get all the details from the journal, but for those of you on the go the researchers compared a conventional solar array with a vertical, bifacial one.

As may be expected, they found that the conventional array generated more electricity, but the vertical array performed well on a holistic level, including water conservation. “The results highlight that vertical AV [agrivoltaics] can generate renewable energy while reducing the water demand of irrigated main crops of the region,” they explained.

“Results for the climatic year 2021 indicate that a north-tilted power plant produced more energy than a bi-facial vertical AV [agrivoltaic] plant, but the latter represents a significantly less [sic] impact on agricultural activities,” they emphasized.

In an interesting twist, the research suggests that the pattern of energy output from vertical arrays could actually be an advantage in regions where the grid is already over-saturated with solar power during peak midday generation periods.

“The analyzed vertical AV presents a lower impact to the grid due to the two peaks in daily power production that spread the generation over the day and does not contribute to the overproduction in the midday,” the researchers explained.

The researchers also noted that water conservation related to shading was enhanced by the wind-breaking effect of the vertical panels.

Agrivoltaics In Chile: Who’s Gonna Pay For All This?

The big question is whether or not agrivoltaics pays off economically, and the answer can be extremely complicated. The widely accepted formulation is to calculate the levelized cost of energy (LCOE), which provides a baseline for comparing the cost of different kinds of energy resources and energy projects.

However, when CleanTechnica attended the 2023 Ocean Energy Europe conference last month, we caught wind of a counter-argument bubbling up. At the conference, stakeholders in the wave and tidal energy industries made the case that LCOE is just one factor to consider, especially when other energy options are impractical.

A similar de-emphasizing of LCOE could go to work in Chile, where beekeepers are losing hives due to a prolonged drought, pesticides, fertilizers, and other factors.

The complementary fields of regenerative agriculture, organic farming and agrivoltaics could help ease the pressure on the nation’s honey industry. In addition to the importance of bees to the country’s agriculture industry, Chilean honey has also become a featured agricultural export for the country, as CleanTechnica learned during a Chilean agriculture event in New York hosted by the ProChile promotional branch of the country’s Ministry of Foreign Affairs.

With that in mind, let’s take a look at a research project that replaces the conventional LCOE calculation with a more holistic approach. The study was presented to a conference of the American Institute of Physics last year under the title, “Price for covering cropland with an agrivoltaic system: PV panels replacing shading nets in Chilean blueberry cultivation.”

The study explored the use of solar panels as an economical alternative to the disposable plastic nets typically used by farmers in Chile to protect their blueberry crops from overexposure to the sun.

“… the sole consideration of PV economics does not do justice to the synergetic effects that agrivoltaic can have on agriculture,” the authors emphasized. “Various researches have stated that agrivoltaic could serve as an alternative for crop protection in (semi)-arid and dry regions.”

The researchers developed new metrics that compare the agrivoltaic solution with the conventional practice, using a blueberry orchard in Ovalle in the Coquimbo Region of Chile as their model.

“…depending on the local cost structure of crop protection with plastic cover, agrivoltaic can create notable synergies when the plastic cover and thus corresponding costs can be avoided,” the researchers concluded. While plastic nets are inexpensive for a single year, replacement and installation costs continue over the following years. In contrast, solar arrays typically last for 20-25 years.

“We highlight the impact of reducing additional CAPEX and conclude that if additional CAPEX can be limited to about under 150 $/kWp, the price for crop cover with agrivoltaic systems can compete with the price for crop cover with shading nets,” they affirmed.

The researchers also cautioned that further research is warranted. We’ll be keeping an eye on new developments in Chile, where Germany’s Frauhofer Institute has been conducting a multi-site study. In the meantime, if you know of any new developments in the agrivoltaic field, drop us a note in the comment thread.

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Image: Bifacial photovoltaic panels collect solar energy on both sides, courtesy of NREL.