Sunday read: Building PV for the future

From pv magazine ISSUE 01 – 2021.

Politically, the Paris Agreement has acknowledged the need to pursue efforts to limit global temperature rise to 1.5 C. For more than a decade, solar PV plants have played a major role in decarbonizing our economies. But the emerging challenge is to go beyond just reducing carbon emissions – real efforts are also required to capture them. According to a recent IPCC report on Climate Change and Land, soil carbon sequestration and reforestation practices are two of the biggest carbon removal opportunities.

Regenerating soils underneath ground-mounted PV panels has the potential to capture carbon emissions. Even agrivoltaics – the coexistence of agriculture and electricity production, if environmentally sustainable practices are implemented – has the potential to remove CO2 from the atmosphere, in addition to fostering food production resilience.

This year the EU has formulated its biodiversity strategy. It is aimed at building our societies’ resilience to climate impacts, forest fires, food insecurity, and disease outbreaks. Recent research from the German energy market innovation association BNE has shown that large-scale PV plants, if designed to be compatible with nature, deliver positive effects on biodiversity, compared to most conventional and monocultural uses.

Dual use

Agrivoltaics has increased exponentially from around 5 MW in 2012 to roughly 2.9 GW in 2018, with national funding programs in Japan, China, France, the United States, and now South Korea. Releasing the pressure on land is even more fundamentally important, as future needs for carbon-neutral electricity increase due to the electrification of transport, coupled with rising demand for afforestation to capture carbon emissions.

There are a wide range of examples for land use beneath PV panels. These include simple sheep grazing for natural vegetation management, annual crops, perennial planting, horticulture, and even aquaponics coupled with PV, where both fish and plants are cultivated in water shaded by a PV system.

The economic opportunity scale is governed by both potential savings and additional expenditures – a balance that depends on a multitude of project specifics. For example, added costs might come from elevated structures, due to concerns about dealing with increased wind speed at height, burying cables in the case of cattle grazing, and planting hedges to naturally preserve the soil. Additional costs can also be incurred by incorporating specialized technologies such as bifacial modules, in order to allow the sun to penetrate or even filter out the light spectrum relevant to PV and the crops beneath. On the cost-savings side, the structures can double up as greenhouses to control heat, provide protection from birds, and cool or control irrigation. And as with all PV innovations that reach economies of scale, costs are likely to decrease over time.

Designing an optimal system for both solar PV and agricultural uses will impact the amount of energy produced by a solar plant. Often systems are built with an increase in spacing between the panels, reducing total energy production. The tilt of the panels may not be optimally designed to maximize electricity, but rather to minimize or control shading of the undergrowth. Even vertical bifacial modules could be beneficial in this emerging competition for the sun.

While in some parts of the world, increased shade is beneficial, every ray of sunlight is required in other regions. In the end, it is the bottom line figure from the returns of both the electricity as well as the agriculture that needs to be assessed and optimized together.

While agrivoltaic tariffs in many countries are the same as those for ground-mounted PV, France has a long history of supporting greenhouse solar PV projects with special tariffs. Criticism of unused greenhouses for agricultural purposes or misclassification of land has highlighted the need for improved selection and permitting for sustainable projects only.

Under current regulations, the business case for agrivoltaics is characterized by higher revenues from electricity on the one hand, and lower returns from agriculture and the lack of revenues for potential ecological roles on the same piece of land on the other hand. This is particularly challenging and it creates tension between the energy and farming sectors.

Multiple roles

The least-known fact about ground-mounted PV projects is their carbon sequestration potential from regenerating soil underneath the panels. This is thanks to the reduced need for insect control or tractor movements, and it is likely to be even better without annual crop farming. Carbon uptake in enriched soil can be achieved by increasing plant varieties that have deeper roots, adding organic materials, and changing crop rotations, among other opportunities.

PV projects are becoming increasingly recognized as a potential contributor to improved biodiversity outcomes. Multiple studies have shown that as the unused area underneath PV panels regenerates and rewilds, biodiversity returns to the fields, attracting smaller wild animals and plant species. After evaluating 75 PV parks in Germany, the BNE concluded that PV parks have a fundamentally positive effect on biodiversity, especially for insects, reptiles, and birds.

A leading example for environmentally sustainable PV project development is being done by Wattmanufactur, a small German company that designs and constructs PV parks with ecological criteria considered right from the start. Its subsidiary, Osterhof Ökologisches Flächenmanagement, is a service provider for ecological PV park management. It maintains on-site habitats including ponds for amphibians, bird and bat houses, trees, and hedges. The company aims to integrate agricultural practices such as beekeeping, sheep grazing, and haymaking via sustainable grass cutting practices.

The BNE recently published a checklist of best practices for PV developers and owners to incorporate environmental factors and other sustainable practices to enhance biodiversity. Many German solar players, such as BayWa r.e., juwi, and Enerparc, have already committed to adopting these practices. In the absence of a strong legal framework to enhance biodiversity in and around PV parks, industry leadership in this area is timely.

Different responsibilities

Owners, developers, and financiers are looking beyond the economic return of solar PV projects, in order to accept their responsibility in building in climate and ecosystem resiliency. Imagine a future in which every PV player commits to playing their part, with careful application of this responsible approach in every phase, in order to ensure that either the quality of the soil is enhanced to allow for carbon removal, the biodiversity is improved, or the crops are sustainably optimized. This is what industry leadership looks like – moving faster than politicians can – to address ecological challenges here and now. Are you ready to be part of it?