The world is rapidly adding solar capacity, but rooftop solar still faces structural and economic problems. Conventional panels are heavy, require roof penetration, and generate most of their power at midday, exactly when grids in solar-heavy regions are already oversupplied. Many existing buildings also have strict weight limits, aging roof membranes, or green roofs that make traditional installations risky or impractical. As energy markets move toward dynamic pricing, excess midday power is often worth less, reducing the financial returns of standard rooftop systems.
Over Easy Solar addresses these challenges by rethinking how solar panels are mounted on flat rooftops. Instead of tilting large panels toward the sun, the company uses compact, vertical, bifacial panels that generate more power in the morning and afternoon when electricity is more valuable.
To better understand how they are doing it, we spoke to Trygve Mongstad, CEO of Over Easy Solar. This article contains notable highlights from our entire conversation.
This interview is part of our exclusive Scouted By GreyB series. Here, we speak with the founders of innovative startups to understand how their solutions address critical industry challenges and help ensure compliance with industry and government regulations. (Know more about startups scouted by GreyB!)
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““Just applying a conventional solar system on top of a green roof is not a good idea, and vertical solar panels solve all those challenges beautifully.”
Trygve Mongstad is the Founder and CEO of Over Easy Solar. Under his leadership, the startup has gained early recognition, including winning the SolarPower Europe Startup Award in 2022. The company also completed one of the first pilot installations of vertical photovoltaic (VPV) units on a green roof in Oslo.
Before founding Over Easy Solar, he served as a Senior Solar Energy Advisor at Asplan Viak, specializing in solar solutions for commercial and public buildings. He also managed large-scale rooftop and building-integrated PV projects across Norway. In addition, he served as an Associate Professor at Oslo Metropolitan University, where he taught engineers how to design compliant, high-quality rooftop solar systems.
Vertical solar panels could fix green rooftop solar’s biggest bottlenecks
Over Easy Solar develops vertical photovoltaic systems designed specifically for flat rooftops. By leveraging modern bifacial solar cells, their compact panels capture light from both sides and are arranged vertically in prefabricated, freestanding units. These systems are lightweight, require no roof penetration, and are easy to remove and reinstall during roof maintenance.
The company focuses on rooftops that struggle with conventional solar installations, including weight-limited buildings and green roofs, while also improving the timing and value of solar energy generation.
What exactly does Over Easy Solar do, and what problem are you solving?
Trygve: We focus on vertical photovoltaics for flat rooftops, using bifacial solar panels that generate power from both sides. While bifacial panels are now standard in manufacturing, most installations still use them in conventional tilted setups. This only takes full advantage of one side. Our product adapts this technology into a prefabricated vertical unit that sits directly on flat roofs.
The problem we’re solving is that many rooftops simply aren’t suitable for traditional solar. This is either because of weight limits, roof conditions, or long-term maintenance concerns. At the same time, grids are struggling with excess midday solar power. Vertical panels help address both issues by being lighter, easier to install, and better aligned with real energy demand.
Why does mounting solar panels vertically make sense from an energy and grid perspective?
Trygve: Conventional solar panels all peak around the same time, that is, midday, when the sun is highest. As solar penetration increases, this creates oversupply in the grid, pushing prices down to zero or even negative in some markets. That’s not ideal for utilities or building owners.
Vertical panels behave differently. They generate less at midday but more in the morning and afternoon. This aligns better with building energy use and grid demand, and in markets with dynamic pricing. It can actually improve the financial return of a solar installation.
Your panels are much smaller than traditional ones. Why did you choose this form factor?
Trygve: Tall vertical panels create major wind load challenges on rooftops. They often require heavy anchoring or roof penetration, which defeats the purpose. By using smaller panels, about 25 centimeters tall, placed close together, we drastically reduce wind loads.
This allows our systems to stand securely using their own weight and friction, without being fixed to the roof. The result is a lightweight, freestanding product that’s easier to install and safer for the roof. It is also easier to remove if the building requires maintenance later.
How does your technology compare to conventional panels in terms of performance?
Trygve: We focus heavily on both usability and performance. From a technology standpoint, we use heterojunction solar cells, which have very high bifacial efficiency, around 95% on the backside compared to roughly 70% for typical panels.
The real advantage comes from the generation profile and the ability to install solar on rooftops that otherwise couldn’t support it. In many cases, that leads to better overall value rather than just higher peak output.
Is Over Easy Solar more expensive than traditional rooftop solar?
Trygve: On a pure equipment basis, yes, our product currently costs more than commodity solar panels. But cost shouldn’t be judged only on the upfront price. You need to consider the value of the electricity produced, the ease of installation, and long-term maintenance costs.
Our systems are easier to maintain, simpler to remove and reinstall, and better suited for buildings with roof constraints. Over a 25- to 30-year lifetime, those factors can make a significant difference in total cost and usability.
Green roofs are a key focus for you. Why don’t conventional solar systems work well there?
Trygve: Green roofs are designed for water retention, biodiversity, and temperature regulation. When you install conventional solar panels on them, you essentially turn the roof back into a black surface. That disrupts water flow, blocks plant growth, and increases maintenance problems.
Vertical solar panels allow the green roof to function almost as if the solar system isn’t there. Light and rain can still reach the vegetation evenly, and access for maintenance remains simple. It’s a much more natural fit.
What technical challenges are you working on right now?
Trygve: We recently launched the third generation of our product, which is a big step forward. Right now, our main focus is commercial traction and scaling rather than radical redesigns.
That said, solar technology evolves extremely fast. We work closely with manufacturing partners, especially in China, to continuously test new cell technologies, materials, and production methods so we can integrate improvements as they become viable.
How do you see Over Easy Solar expanding in the future?
Trygve: We’re still a small team, so we have to stay focused. Flat rooftops alone represent millions of square meters globally, so there’s huge potential just within that niche.
In the long term, we see opportunities in new geographies and use cases. For example, in regions with high dust or soiling, vertical panels could offer additional benefits. As we grow, we hope to explore those markets in a structured way.
On a personal level, what keeps you confident about building a company in such a competitive industry?
Trygve: What motivated me was the uniqueness and scalability of the idea. Flat rooftops exist everywhere, and they all face similar challenges. That makes this solution highly scalable.
Solar entrepreneurship is tough, but it’s meaningful work. If you believe in the impact and keep solving real problems, that belief helps you push through uncertainty and keep moving forward.
Meet our Interviewer – Shabaz Khan, Marketing Manager at GreyB
Shabaz Khan, Marketing Manager
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