The big problem with putting solar panels on crops is shade. The University of Jaén has found a solution

In search of fulfilling the decarbonization goalswe are filling the field with solar panels. Giants like China can do it combining other activities well, but in the case of smaller countries, things change. Spain is an examplewith a field irrigated by crops that is also being plagued by panels. Now, a research team from the University of Jaén has found the key to continue deploying solar panels without interfering with crops.

A panel with minimal shading that does not compromise its energy generation.

The agrovoltaics. Different reports have pointed out how the temperature will increase by 1.5 to 3.2 degrees If we continue the same as until now. For this reason, the European Union marked the milestone of 30% of its energy comes from renewables by 2030 to, in 2050, achieve climate neutrality. Wind is important, but what almost all countries are embracing is photovoltaics.

The price of the plates has fallen to the ground thanks to the China overproduction and it has begun to be deployed massively. The problem is what we mentioned: it takes up a lot of space, which opens a direct conflict with the farmland. There, agrovoltaics is becoming established as a solution to place panels that do not interfere with the cycle of some crops, and mixes with beekeeping and the livestock. But if we want to continue expanding photovoltaics, panels that provide less shade are needed.

Panels and photosynthesis. That is where the solution devised by the University of Jaén comes into play. In a study Published in Science Direct, researchers detail a technology that allows a panel to efficiently generate electricity, while allowing crops to receive enough light to perform their optimal photosynthesis cycle.

To do this, the team has taken into account two technical parameters: the average visible transmittance and the average photosynthetic transmittance. In practice, they indicate the amount of light useful to the plants that reaches them after passing through the panel, and they point out that different studies estimate that, for most crops, the minimum value should be around 60%. In that spectrum, plants produce normally.

Status of the “transparent” panels“The photovoltaic industry has been working on this for some time. There are two approaches:

• Non-wavelength selective panels: They are those that absorb a large part of the solar spectrum and achieve transparency by reducing the color of the material or leaving gaps between the cells. With them, transparency is not adequate.
• Wavelength Selective Panels: They are those that absorb, above all, ultraviolet and near-infrared radiation, but allow a large part of the visible light to pass through. It is what the plants need and, in this case, the transparency of the panels is greater and more suitable for crops.

RearCPVbif. In the two groups the industry is testing very different technologies, from polycrystalline silicon to organic cells and color-sensitized panels, but the Spanish team’s approach is somewhat different. The semi-transparent photovoltaic modules They are the STPVs, but what is proposed by the University of Jaén is a system called RearCPVbif, or “Bifacial Rear Concentrator Photovoltaic.”

Unlike conventional semi-transparent designs, this technology concentrates and redirects reflected light towards the back of the bifacial cells, generating an increase in electrical production without reducing optical transparency, which is what allows light to reach the plants. It is an STPV, but with rear optical concentrators.

In statements to PV-MagazineÁlvaro Varela-Albacete, co-author of the research, points out that STPV technology is being underused and that, with these rear concentrators, there is “a substantial increase” in energy generation without compromising optical transparency. “And how much is the transparency factor? 60%, according to the study, so it would be suitable for most horticultural crops.

Next steps. In the study they also mention that they have taken into account that a crucial aspect for agricultural viability is thermal behavior, indicating that, in their tests, the cell temperature was below 70 degrees. This is important so that the panels do not create a “greenhouse” that affects crop patterns.

And most importantly: this technology has already attracted attention. Numerous promising studies are published throughout the year, but their application is not always clear. In the case of this ReadCPVbif technology, the co-author of the study, Eduardo Fernández, points out that they are already engaging in conversations with different organizations to accelerate the development of the technology.

Now, the route hour includes an evaluation of the benefits for crop growth, with different test campaigns on real crops. In any case, it aims to be a particularly relevant technology in the intensive horticulture that occurs in regions of Spain such as Almería, where apart from the sea of ​​plastic, also the photovoltaic sea is rising. If the two things can be combined, it would be a great step for both sectors.

Images | University of Jaen, Σ64

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