In Japan, floating solar panels navigate tricky terrain with generative design

As the demand for carbon neutrality grows, floating photovoltaic (PV) power generation—or floating solar—has become a big part of the sustainability conversation for good reason. Floating PV systems serve two purposes: generating electricity and storing water. Their environmental impact is small due to a minimal footprint, provided the water sources used lack aquatic life.

Floating PV systems are not obstructed by trees and other plants, giving them direct access to sunlight throughout the day. Also, water has a cooling effect, which makes solar panels more efficient. The young floating PV market’s standards are still being developed, but adoption is quickly expanding, especially for areas where traditional, mounted panels aren’t viable. It also aligns with net-zero emissions pledges across the globe; countries like Japan have passed laws committed to net-zero by 2050.

Japan has a limited amount of land with good lighting for PV systems, even in mountainous areas. Where they do exist, large-scale mountain forests must be cleared, which is counterintuitive to the zero-carbon initiative.

Japanese industrial designer Satoshi Yanagisawa is no stranger to the ecological risks that solar power generation on mountainous, sloped land can pose. “In Japan, making solar power systems on mountainsides and similar locations is becoming problematic because trees are being removed,” he says. “Chopping down natural green resources to build something that’s supposed to benefit the environment is complete nonsense. We need to stop using land for power energy projects. Water is more reliable.”

Yanagisawa is the head of Tokyo-based design studio Triple Bottom Line. His studio has a unique focus on a hybridization of modalities from functional interior design products to sustainable machines and mass-producible infrastructures. As a designer, Yanagisawa is naturally drawn to aesthetically pleasing shapes and lines. But as an engineer, he believes that objects should always have a practical function and should be easy to commercialize. It’s an ongoing pursuit to find a balance between those two sensibilities.

Originally from Japan, Yanagisawa attended university in the UK, where he studied design engineering and material engineering with a focus on product design and sustainable furniture. Generative design—which uses algorithms driven by artificial intelligence (AI) to generate a wide range of design options well beyond what a team of humans can do—appealed to him early on, and has created many opportunities to hone his craft and explore practical solutions.

Yanagisawa’s portfolio includes everything from LED pendant lights to a 3D-printed road bike with Internet of Things (IoT) functionality, which won him a CES Innovation Award in 2016. He also worked on the 2019 iF Design Award-winning DENSO engine control unit (ECU), which uses generative design to reduce the weight of an automobile ECU by at least 12%. His most recent accomplishment is a floating device used to generate solar power on water—a project that Yanagisawa and a small team of five completed in just six months. He estimates this process would have taken more than two years without strategically applying generative design in Autodesk Fusion 360.

A general contractor in Japan was hired to develop a new kind of float for PV systems but didn’t have the mass-production knowledge or background needed to make the deadline, so Yanagisawa was called in for his expertise.

The contractor had already spent many hours and a good portion of the budget on employee training and sought a way to avoid starting from zero. A project stakeholder knew Yanagisawa’s work and thought his background aligned with the mission.

At the time, Yanagisawa was working with a small team and decided early on that traditional design and testing methods would not suffice, considering the client had only 15 months to complete the entire project. Many floating PV systems had already been developed, but the actual floats weren’t standardized and needed to be designed from scratch. Yanagisawa applied generative design, which quickly turned out 500 float shape options with minimum and optimum wall thickness, based on the assumed strength needed.

“Even with the 500 solutions, we realized we needed to modify a few things to meet certain standards,” Yanagisawa says. “We had to make modifications to the concept models based on feedback from the engineers on the factory side who would be responsible for production. The process is known as DFM [design for manufacturing] or MVT [mass-production verification test], which is generally mandatory for mass-produced products. We also needed to avoid conflicting patent issues as there were already two major companies in the world that did floating PV systems—a French company and a Chinese company.”

Laws, regulations, and standards related to floating solar systems are not fully developed yet, so Yanagisawa and his team established their own standards for the floats based on well-researched existing standards for land-based power generation equipment, floats, and anchors in other fields, as well as standards for water pollution. While incorporating necessary functional design elements, they narrowed 500 options down to just a few and ultimately settled on a final design.

Once Yanagisawa and his team completed the design prototype, they needed to test the device in a suitable location. They chose Kagawa, a Japanese prefecture in the northeast of Shikoku Island that’s well known in the agricultural industry. The Kagawa soil is fertile and conducive to crop production, and to make up for minimal rain, the locals have developed their own self-sustaining water supply.

To verify the floats’ functionality, a testing facility in Kagawa was created in collaboration with locals in the agricultural industry. There, they began generating their own electricity to power the facility. Computer-aided engineering specialist Misao Mizuno, an expert in structural analysis and fluid dynamics, was enlisted to help throughout the testing phase. He used simulation to analyze whether the model met specific performance requirements.

“Computer simulation speeds up the development process and also helps reduce the waste from validation work, as it reduces the need for physical testing,” Yanagisawa says. “The original plan was to test the actual product for five to six months, but since Misao could replicate most of the tests in the simulation environment, the time was reduced to two months.”

After the two-month period, Yanagisawa’s floats passed and have been cleared for mass production. “Our system has been working,” Yanagisawa says. “Right now, it’s only in some Asian fields because there’s no globally standardized safety regulation yet, but a few European companies are interested.”

PV power generation is still an emerging market, and some new regulations must pass for companies to justify funding something of market scale, but there’s definitely momentum. Generative design opens up all types of opportunities for rapid prototyping and testing floating solar; mainstream acceptance could be on the horizon.

With a growing population using more space on the planet, outside-the-box solutions like Yanagisawa’s floats could potentially make a huge impact on sustainability. “Originally, I’m a designer, and I want to make beautiful, clean things,” he says. And he would love to see a better translation of style within AI and generative design.

“Currently, generative design focuses on proposing mass- and structure-optimized models based on mechanical properties, price, and so on,” Yanagisawa says. “It is not making aesthetic decisions, but merely processing to meet the mechanical and functional requirements established under specific conditions using metacognition given in advance. The AI’s answers may seem disjointed, but to truly collaborate successfully with AI, we need to correctly understand the design language they use and translate it into our own.”

Yanagisawa also hopes to solve creating floating solar for the sea. Of course, with sea-based PV systems, there are extreme elements to contend with, including rising sea levels, harsh conditions, and the impact floats could have on biodiversity. Perhaps generative design will be able to pinpoint environmentally friendly solutions in this arena. The collaboration between humans and AI is exciting territory, and when they can build on each other’s strengths, the possibilities are limitless.