Europe’s rooftop solar gap and the case for lightweight solutions

Europe’s rooftop solar potential is a trillion-euro opportunity for C&I

According to the European Commission’s Joint Research Centre (JRC), current rooftop solar installations account for only about 30% of the EU’s potential, leaving a whopping 70% of rooftop PV capacity untapped

The JRC estimates that Europe could technically install up to 580 GW of rooftop solar PV, generating around 680 TWh per year, enough to cover roughly 25% of the EU’s total electricity demand in 2023.

Further supporting this, another high-resolution study confirms that rooftop PV could generate 680 TWh annually, or about 24–25% of current EU electricity consumption

The European Commission’s Joint Research Centre (JRC) has mapped the technical potential and the numbers are striking:

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Put differently, if all technically suitable rooftops were equipped with solar, one quarter of Europe’s electricity demand could be met by power generated directly where it is consumed.

Why this matters for C&I stakeholders and businesses

For commercial and industrial players, the untapped rooftop potential is a financial topic. Every kilowatt-hour generated on the roof offsets electricity purchased from the grid, turning previously unused real estate into a profit-generating asset.

• Direct savings: At average wholesale prices of €0.07–0.15 per kWh, the 680 TWh of unrealized rooftop generation equates to €47–102 billion in avoided grid purchases every year.
• Stability: Onsite generation insulates businesses from volatile energy markets, a major concern since the price shocks of 2021–2023.
• Profitability: Reduced energy costs flow directly into operating margins, supporting competitiveness in energy-intensive sectors.

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Why lightweight design closes the rooftop solar gap

If rooftop solar is such a compelling opportunity, why is only 30% of the potential being used? EPCs and building owners point to three recurring barriers:

• Structural limits: Many roofs cannot bear the additional load of conventional glass modules.
• Reinforcement costs: Strengthening a roof can add €150,000–200,000 per MW, making projects financially unviable.
• Project delays: Reinforcement or roof replacement extends timelines by months, reducing ROI and creating financing hurdles.

Structural limits, however, remain a Europe-wide challenge. According to the European Commission’s Joint Research Centre, only around 30% of the EU’s rooftop solar potential is currently being used, leaving 70% untapped. While part of that gap is due to permitting and investment hurdles, structural load restrictions are a recurring barrier across commercial and industrial buildings.

In Germany, TÜV Süd found that just 25% of rooftops were fully suitable for PV without restrictions, with a significant share excluded due to weight concerns. In Spain, only about 17% of PV capacity comes from industrial buildings. Italy shows similarly modest commercial rooftop uptake. In Eastern Europe, adoption lags even further. Poland’s rooftop solar market, for example, is overwhelmingly residential. More than 1.5 million micro-installations account for over 12 GW of capacity which is well over half of the national PV total. In contrast, the commercial and industrial rooftop segment lags significantly, mirroring broader European patterns where residential setups dominate the market.

For C&I businesses and EPCs, lightweight solar modules could be the key to unlocking this underused rooftop segment. By cutting the load of conventional PV systems by 30–40%, they enable projects on roofs that would otherwise be excluded. This could unlock a substantial share of the EU’s 70% untapped rooftop potential, converting technical capacity into viable business opportunities.

Lightweight modules directly address these barriers. By reducing system weight, they allow solar to be deployed on roofs that would otherwise be excluded. At the same time, they avoid reinforcement costs and enable faster project execution.

The economics of solar show clear payoffs for businesses

In order to exploit the vast potential of commercial and industrial solar, companies need to recognize the financial dimension. Rooftop PV is no longer driven only by sustainability targets but by solid business economics. When structural barriers are addressed with lightweight solutions, solar becomes a direct lever to reduce costs, stabilize energy spending, and strengthen margins.

Case example of a logistics warehouse in Central Europe

Consider a logistics warehouse with a 20,000 m² low-load bearing rooftop:

• System size (lightweight modules): 2 MWp
• Annual generation (yield ~1,000 kWh/kWp): ~2,000,000 kWh
• Average electricity price (conservative €0.10/kWh*): €200,000 annual avoided grid purchase
• 30-year lifetime: ~€6 million in avoided electricity costs

(*Actual 2025 industrial prices in Central Europe average €0.18–0.23/kWh, meaning the real savings potential could reach €360,000–460,000 annually for the same rooftop system.)

If conventional modules had been chosen, roof reinforcement would have added €350,000 to CAPEX and delayed commissioning by four months. By opting for lightweight modules, the warehouse not only saved €350,000 upfront but also started generating energy and savings 120 days earlier, adding ~€65,000 in first-year benefit.

From a business perspective, the impact is material: For a logistics operator with around €5 million in annual electricity costs across its portfolio, one installation of this size reduces total spend by about 4% under the conservative €0.10/kWh assumption. Scaled across ten comparable rooftops, the same approach delivers roughly €2 million in yearly savings at €0.10/kWh, improving profit margins and reducing exposure to price volatility.

Unlocking a trillion-euro scale market over the coming decades

When viewed at scale, the financial significance of Europe’s untapped rooftop solar potential becomes clear. Even if only half of the unused 70% were deployed, businesses could collectively avoid hundreds of billions of euros in grid electricity purchases over the systems’ lifetime.

Lightweight solar modules will be critical to unlocking this opportunity, particularly for C&I portfolios with diverse and often structurally constrained building stock. They turn the theoretical potential mapped by researchers into bankable, revenue-generating projects.

For C&I stakeholders, the message is clear: every kilowatt-hour produced onsite strengthens competitiveness, reduces risk, and improves margins. Lightweight modules remove some of the most persistent barriers, making it possible to turn idle rooftops into productive, income-generating assets. The rooftop revolution in Europe is less a question of technology than of unlocking what is already within reach.

Hi-MO X10 Guardian Light Design unites back contact performance with a 30% lighter build

To address this challenge, LONGi developed the Hi-MO X10 Guardian Light Design module, a solution built on advanced back contact cell technology and engineered with a 30% lower weight than conventional glass modules. This combination makes high-efficiency solar feasible on rooftops with limited load-bearing capacity, where reinforcement would otherwise block the business case. By pairing cutting-edge technology with structural compatibility, the Light Design module turns previously excluded commercial and industrial roofs into viable, long-term energy assets.

Get the datasheet here or read on the Light Design on our product page.

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