In southern Germany, a turquoise gravel lake has quietly become a power plant. Instead of building a classic solar farm on fields or rooftops, engineers have covered part of the water with long rows of upright solar panels that float on the surface.

The project sits in Bavaria at the Jais gravel pit and is described as the world’s first vertical floating solar plant. Developed by SINN Power, the system has an installed capacity of about 1.87 megawatts and is expected to generate roughly 2 gigawatt hours of electricity per year, enough to power several hundred homes while using only 4.65% of the lake surface.

Floating solar that sidesteps the land problem

Floating solar is simple to picture. Instead of mounting panels on soil, developers place them on rafts or modular floats so they sit on reservoirs, quarry ponds, or industrial lakes. A market study from the U.S. Department of Energy notes that this approach can unlock clean power in places where land is scarce or expensive, while also cutting evaporation from the water below.

Germany has strict rules for these projects. Under current interpretations of the Water Resources Act and related rules, floating solar systems can usually cover at most 15% of an artificial lake and must keep a buffer from the shore.

A study by the Fraunhofer Institute for Solar Energy Systems ISE found that the country has more than 6,000 artificial lakes with over 90,000 hectares of surface area, yet only around 21 megawatts of floating solar are in operation with about 62 megawatts under construction, far below an estimated potential of 1.8 to 2.5 gigawatts.

Inside Bavaria’s vertical solar lake

The Bavarian plant uses SINN Power’s patented Skipp Float technology, which mounts bifacial solar modules vertically in long east-west rows instead of laying them flat. Around 2,500 modules stand like glass fences across the lake, while open water corridors roughly four meters wide separate each row so sunlight and wind can still reach the surface.

Below the waterline, a keel-like structure extends to about 1.6 meters depth and ties into a cable network, so the platform can flex with waves but stay stable during storms and changing water levels. Because the panels are vertical, developers can install more generating capacity within the same legal footprint while still staying well under the 15% coverage limit.

Cutting grid use and electric bills at the Jais gravel plant

For the gravel company, this is more than a showcase project. Crushers, conveyor belts, and pumps use a lot of electricity, especially on bright workdays, and early operation of the floating plant has already cut the site’s power draw from the public grid by close to 60%.

Projections from SINN Power suggest the share of self-generated electricity could reach about 70% once a planned second phase adds another 1.7 megawatts of capacity. “It is a relatively simple solution that does not need additional land and fits our plant, which runs mainly during the sunny months from March to December,” explained gravel pit manager Gottfried Jais.

In practical terms, producing power on site when the machines are running helps shield the business from price swings on the wider grid and, over time, should trim a noticeable chunk off its electric bill.

What happens to the lake ecosystem?

One common worry with floating solar is its impact on life under the surface. At the Jais gravel lake, designers left wide water corridors and limited coverage to less than 5% of the surface so that air can circulate and sunlight can reach the water column. Early monitoring suggests no decline in water quality, and the shaded zones may even act as shelter for fish and waterbirds that now rest on the floating structures.

Scientists are still cautious. A 2022 review by researchers at the University of Exeter in the journal Clean Technologies found that floating solar can ease land pressure and reduce evaporation, yet called for more long-term data on how these systems affect oxygen levels, temperatures, and aquatic species. That makes the Bavarian plant an important real-world test case rather than a final verdict on how every lake will respond.

A glimpse of future renewable lakes

Zooming out, the idea of vertical, floating panels is attracting attention because it matches energy output more closely to how people actually use power. SINN Power and other analysts say east-west vertical layouts tend to produce more electricity in the morning and late afternoon compared with classic south-facing arrays, which helps cover the busy hours when factories are running and households are cooking, cleaning, or charging cars.

The regional development agency gwt Starnberg GmbH and local authorities see the project as a model for other gravel pits and industrial lakes, and Bavarian leader Markus Söder has highlighted it as proof that renewable innovation can happen close to home rather than only on distant offshore wind farms. For anyone who has driven past a quarry or reservoir and seen only unused water, it raises an obvious question, will more of those blue surfaces soon double as power plants?

The main press release has been published on the SINN Power GmbH website.

Image credit: SINN Power