Why we should use our fields twice

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Photovoltaics produces 30 times more energy per hectare than energy maize for biogas. The Thünen Institute has done the math: silage maize yields about 23,000 kWh of electricity per hectare per year. A ground-mounted PV array yields around 700,000 kWh. Seven households versus 230 households — from the same hectare.

In Germany today, roughly 2.2 million hectares are used for energy crops — biogas maize, rapeseed for biodiesel, grain for bioethanol. That is more land than solar would need to cover Germany's entire electricity demand. We don't have a land problem. We have an efficiency problem.

But the question isn't: solar plant or agriculture. The question is: why not both?

What is agrivoltaics?

Agrivoltaics — also called agri-PV — is the dual use of farmland for food and electricity. The variants that now exist are more diverse than most people think.

1. Elevated systems

The solar modules hang five meters up in the air. Beneath them, the land is farmed completely normally — wheat, potatoes, celery, clover. Tractors and combine harvesters pass through without trouble. At the Heggelbach research site on Lake Constance, the Fraunhofer Institute measured: the combination of harvest and electricity boosted land-use efficiency up to 186 percent in the hot summer of 2018, averaging around 160 percent. One hectare effectively becomes 1.6 to 1.86 hectares.

The harvest losses from the shading? Small. In hot summers, even a benefit, because the plants suffer less drought stress.

2. Vertical fence systems

Bifacial modules stand vertically like fences between fields. They produce electricity from both sides — east in the morning, west in the evening — and take up practically no farmland. Agricultural use remains 100 percent intact.

Especially smart: these systems produce most of their power in the morning and evening, exactly when classic south-facing arrays deliver little. That smooths out the feed-in curve.

3. Solar greenhouses

Photovoltaic modules are integrated into the roof or facade of greenhouses. They generate electricity and at the same time protect the plants from hail, heavy rain and excessive heat. At the University of Tuscany, researchers have developed a prototype with rotatable modules — letting through more or less sunlight depending on the light needs of the plants.

4. Grazing under modules

A study by the University of Göttingen shows: on hot days, sheep prefer the shaded areas under solar modules. The grass underneath even has a higher crude protein content. The sheep keep the vegetation short, and the operator saves on mowing.

In Lower Bavaria, bison, Angus and Galloway cattle graze on a 50,000 square meter solar site. "Solar grazing," they call it — and it saves farms: one shepherd told agrarheute that without the PV system she would have had to give up her 20 ewes.

5. Peatland PV

Drained peatlands cause around 42 million tons of CO₂ equivalent per year — almost half of all greenhouse gas emissions from German agriculture, even though they make up only 7 percent of the agricultural area. The Fraunhofer project "MoorPower" (7 million euros in funding, running until 2028) is investigating the combination: rewetting peatlands and putting PV systems on top. Triple win: electricity, fewer emissions, more biodiversity.

6. Fruit farming under power

On Lake Constance, the Bernhard orchard integrates PV modules directly above its apple trees. The modules are semi-transparent (49 percent light transmission) and protect the fruit from sunburn and hail. At the Lake Constance fruit-growing competence center, six apple varieties and two pear varieties are being tested under PV — with the goal of also reducing pesticide use.

7. Aquavoltaics

Floating solar panels on fish ponds and aquaculture basins. The modules reduce evaporation, regulate water temperature and improve living conditions for the fish. Cooling by the water also boosts the efficiency of the modules.

8. Pollinator-friendly solar parks

Wildflower meadows between and under the modules, deliberately laid out as habitat for bees and other pollinators. Solar parks become islands of biodiversity in the middle of agricultural deserts.

9. Tracker systems

Single-axis trackers follow the sun across the day and boost yield by 20 to 30 percent compared to fixed systems. When needed, they tilt vertical so machines can pass through. Roaming shade that reduces heat stress on the plants.

10. Solar sharing — the Japanese original

In 2013, Japan was the first country to introduce a feed-in tariff for agri-PV. Modules on thin stilts above rice paddies, vegetable beds, tea plantations. Thousands of installations have gone up since.

And what is South Tyrol doing?

Nothing. Or almost nothing.

South Tyrol is one of the few regions where ground-mounted PV on agricultural land is heavily restricted. Agri-PV has so far only been permitted for research purposes. The justification: landscape protection.

At the same time, the region's own 2040 climate plan says: South Tyrol needs 1,400 additional megawatts of PV capacity to become climate neutral. Roofs and parking lots alone won't deliver that. At least 500 megawatts would have to come from agri-PV — that is what the Climate Club South Tyrol and EURAC say.

The logic behind it is a classic: only here is it beautiful, so others should do it. Parochialism in the literal sense. We'd rather import electricity from elsewhere than produce our own — even though the sun shines here 300 days a year.

If the generations before us heard that we get our energy from outside when we could make it ourselves, they'd call us crazy. These are the same people who farmed every square meter of slope so nothing went to waste. And us? We import electricity and call it landscape protection.

Agri-PV would barely change the landscape. Modules above apple orchards look no different from the hail nets that hang there already. Vertical fence systems on meadows are barely visible from the nearest hiking trail. And solar greenhouses are greenhouses.

In the mountain areas, where the growing season often lasts only five months, agri-PV systems could give farmers a second source of income — twelve months of electricity, five months of harvest, from the same field. Instead we watch the farms die.

The physics has long been settled

The technology is there. The research is there. The economic logic is there.

Every hectare of energy maize replaced by agri-PV produces 30 times more energy — and the farmer can still work the land. Every pasture where sheep graze under modules produces electricity and meat and wool and biodiversity all at once. Every rewetted peatland with a PV system saves thousands of tons of CO₂.

With full electrification — electric cars instead of combustion engines, heat pumps instead of gas boilers — total energy demand is roughly cut in half, because a large share of today's energy is lost as waste heat. Model calculations show: two to three percent of European agricultural land could be enough to cover the EU's entire energy demand from solar.

What's missing isn't the technology. What's missing is the speed of implementation.

Sources: - Thünen Institute: land efficiency of various energy generation systems (2023) - Fraunhofer ISE: APV-RESOLA project Heggelbach, land-use efficiency 186% - Fraunhofer ISE: MoorPower project (2024–2028), 7 million euros BMBF funding - University of Göttingen: study on animal welfare in sheep grazing under solar modules (2026) - DIN SPEC 91434: requirements for agri-PV systems (2021) - Climate Club South Tyrol / SALTO: "Regulate agri-photovoltaics in time" (05.05.2025) - Südtirol News: "Agri-photovoltaics leads to the goal" - agrarheute: "Sheep between solar modules" (26.02.2026) - energiezukunft.eu: "Wind power and PV significantly more efficient than energy crops" (2023) - pv-magazine.de: ground-mounted PV occupies 45,200 hectares (2025)

Image credits: all photos Wikimedia Commons, CC BY-SA 4.0

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