The business case for lightweight solar modules in industrial companies and EPC projects

If more industries want to turn their rooftops into a solar asset, weight matters

Commercial and industrial (C&I) rooftops represent a major untapped opportunity for solar, as they can generate clean power on-site without adding pressure to the already congested grid.Yet many remain unused because they cannot carry the load of conventional glass modules. Supermarkets, logistics halls, and retail stores often have flat or lightweight roofs that were never designed for heavy additional structures.
Traditionally, developers faced three options: reinforce the roof at high cost, adopt BIPV, or abandon the project. All choices create friction in the business case. Depending on the market, roof reinforcement typically adds between €100,000 and €250,000 per MW in Europe, with Western and Northern countries clustering around €180,000–200,000, Southern projects often a bit lower, and Eastern markets sometimes closer to €100,000.

1 MWp typically requires about 5,000 to 7,000 m² of gross roof area, depending on module efficiency, tilt, and access needs. With high-efficiency modules such as the Guardian Light Design using HPBC 2.0 back contact technology, the roof area requirement can be reduced by around 10–20%.

In every case, reinforcement stretches project timelines by several months. As a result, many viable rooftops remain excluded from the solar transition.

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Glass-based lightweight modules change the equation. With a weight reduction of up to 30–40% compared to conventional glass modules, they make PV feasible on previously unsuitable roofs. But their business value goes beyond pure structural compatibility. They also reduce capital expenditure, shorten project schedules, and unlock earlier returns.

ROI is not only about efficiency

Efficiency remains important in any solar project, but for C&I installations, return on investment is influenced by more than module performance. Balance-of-system (BOS) costs, structural requirements, and financing terms all play decisive roles.
Lightweight modules shift these variables in the right direction. They bring:

• CAPEX savings from avoided roof reinforcement,
• Shorter project timelines leading to earlier revenue generation,
• Reduced insurance hurdles with lower roof impact,
• Reliability in the long-run to minimize maintenance needed during the project operation lifespan

The combined effect is a stronger business case and shorter payback period, even when module costs are comparable to standard products.

Case 1: Avoided reinforcement costs is the biggest lever for a supermarket chain

The heaviest cost item in many C&I projects is not the solar system itself, but the preparation of the roof. When reinforcement is necessary, project viability is often lost. A fictional case example from Central Europe shows how lightweight modules, for example the Hi-MO X10 Guardian Light Design at 7.2 kg per square meter, change the economics on low-load roofs. The setup: A supermarket chain plans a 1 MWp rooftop system on a 6,000 m² building with a strict 12 kg per square meter limit. Standard glass modules would exceed the limit, so the roof would need structural reinforcement. How the costs build up:

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Base PV system
What you pay for modules, inverters, mounting, wiring, and installation.
Modeled at €0.71 per watt, so for 1,000,000 W this is €710,000.

Conventional route with reinforcement
Add the typical roof reinforcement cost in Europe of €0.18–0.20 per watt.
Calculation: €0.71 + €0.18 -0.20 = €0.89 - 0.91 per watt.
Total CAPEX: €890,000 - €910,000.

Lightweight module route with no reinforcement
Modules stay within the load limit, so reinforcement is €0.00 per watt.
Total CAPEX remains the base €710,000.

The consequences
In this case, the lightweight path avoids €180,000–€200,000 compared with the reinforced build, which is roughly a 20–22 percent CAPEX reduction on a 1 MWp project. The saving comes from skipping reinforcement, not from inflating the lightweight system cost. In addition, earlier commissioning and the avoidance of construction downtime create further financial upside, while the IRR typically improves by a couple of percentage points.

Editorial note for readers. This is a modeled, fictional example that uses typical Central European benchmarks for C&I rooftops. The numbers are illustrative, the method is what matters, base PV cost plus reinforcement for conventional compared with base PV cost only for lightweight.

Case 2: Retrofitting logistics warehouse in the south of Europe

As always in life, time is money. In renewable energy that means every week shaved off the project schedule accelerates grid connection and revenue generation. Roof reinforcement typically delays projects by four to six months. Glass-based Lightweight modules, which require only conventional clamp mounting, allow EPCs to move directly into installation.

A second fictional case from Southern Europe shows how lightweight modules can accelerate project timelines and unlock extra financial value. The project in question is a 2 MWp retrofit on a logistics warehouse. Under the conventional plan with standard glass modules and required roof reinforcement, commissioning would take around 14 months. By switching to lightweight modules, the schedule could be shortened to about 10 months. That is a saving of roughly 120 days. This leads to the following benefits.

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Electricity value per month
At a wholesale electricity price of around €0.08 per kilowatt-hour, a 2 MWp system producing about 240,000 kilowatt-hours each month generates roughly €16,000 in monthly electricity value.

Additional year-one revenue from early start
With four months of extra production from the faster build, the warehouse would gain appr. €65,000 in the first year alone.

Reduced financing costs
A shorter construction phase also cuts interest and financing charges. In this modeled example, that equates to appr. €30,000.
In total, the lighter, faster installation delivers an additional €95,000 in direct financial benefit in year one, purely from avoided delays and reduced financing costs. For the EPC, a lighter and faster installation can also free up crews several months earlier, allowing them to move on to other projects sooner and effectively increasing overall business throughput. Instead of waiting over a year for the first kilowatt-hour, the warehouse benefits from earlier energy revenues, improved IRR, and lower financing exposure, all without the disruption of structural reinforcement.

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Editorial note for readers. Like the Central Europe case, this Southern Europe scenario is a fictional, modeled example. The numbers are illustrative, but they reflect the real dynamics: every month saved in construction translates into earlier cash flow, lower capital costs, and higher portfolio efficiency.

Case 3: Unlocking excluded rooftops for a retail chain in Northern Europe

Lightweight modules also unlock entire portfolios that would otherwise be excluded. A fictional case from Northern Europe illustrates this effect. A retail chain with 50 stores had initially found that only about 60 percent of its rooftops were suitable for conventional glass modules. By adopting lightweight modules, the suitability rose to 85 percent. That difference translates into an additional 25 MWp of viable capacity across the company’s network. For the retailer, it meant the ability to double its renewable capacity target without changing its real estate strategy. For the EPC partner, the impact was equally significant, as the shift created around 20 additional projects worth approximately €15 million in new contracts. Based on current EPC benchmarks of €0.60–0.70 per watt for commercial rooftops in Northern Europe, the €15 million portfolio value is at the conservative end of the range, with comparable projects in markets such as Scandinavia or the UK often reaching €16–17.5 million
In portfolio terms, lightweight solutions do not just save costs, they open the door to capacity that would otherwise remain out of reach.

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Glass-based lightweight modules lower both structural risk and insurance concerns‍

Beyond CAPEX and timelines, risk management matters. Roof penetrations, added weight, and reinforcement work can create long-term liabilities. Insurers may raise premiums or require additional guarantees.
Lightweight modules mounted with standard clamps reduce structural stress, preserve the roof membrane, and lower the probability of leakage or warranty conflicts with the building owner. Lightweight designs typically secure faster insurance approval, which not only reduces project risk but can also lower operating costs over the lifetime of the system.

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Making rooftops work harder

Lightweight solar modules are emerging as a strategic tool for developers, EPCs, and building owners alike. They expand the universe of viable rooftops by meeting low load requirements and avoiding costly structural reinforcement that in Europe can add up to €200,000 per MW. Costs vary by region, with Northern and Western Europe typically at the higher end, Southern Europe in the mid-range, and Eastern Europe often in the lower band due to reduced labour costs, while lightweight solutions also shorten project schedules by months and unlock earlier cash flow. At the same time, their lighter, glass-based design reduces long-term risks associated with roof structures and helps secure smoother insurance approval. For building owners, this translates into a faster, cheaper, and safer path to energy independence. For EPCs, it means higher margins and a new pipeline of projects that would otherwise not exist. And for the industry at large, lightweight modules provide a practical solution to one of solar’s most persistent bottlenecks: the underutilization of commercial rooftops.

See how our first Guardian Light Design installation has come into action in China or learn more about our new feature module from the Hi-MO X10 Series.

Contact us for questions or product availability.

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