Large roofs transformed into power stations

Large commercial and industrial roofs harbour enormous potential: thousands of square metres of space, optimally oriented – and often not being used to generate energy. WALO transforms these large roofs into high-performance photovoltaic systems that produce electricity, reduce costs and contribute to the energy transition.

In-house systems as a touchstone – experience from real-world applications

Photovoltaics is not a new business area for WALO – it is an established practice. The company operates several large-scale PV systems on its own buildings with a total output of around 900 kWp. These systems generate over 935,000 kWh of electricity – enough to power around 200 households – and save more than 580 tonnes of CO₂ per year. “We planned and built these systems under real conditions,” says Björn Faes, Photovoltaics Project Manager at WALO. “It is precisely this experience that we are now bringing to customer projects.”

Famobit SA: installation of photovoltaics during ongoing operations

The PV system at Famobit SA in Bussigny shows just how complex large roof projects can be. WALO realised a system with an output of around 263 kWp on the factory building and mixing plant of a gravel works. A total of 558 modules and four inverters deliver an expected annual production of around 300,000 kWh.

Realising the project during ongoing operations was particularly challenging. Logistics, occupational safety and construction processes had to be precisely coordinated. Thanks to detailed planning and close coordination, the project was completed on time and to a high standard – a typical example of photovoltaics in a location which required concepts beyond the standard solutions.

Menziken school building: PV system on a green roof

WALO can also demonstrate its strengths when it comes public buildings. A 159 kWp system with 355 modules and three inverters was realised on an existing green roof for the school building in Menziken.

The challenge was to build a substructure without additional ballast. The existing substrate was systematically relocated and used as ballast – a solution that requires technical understanding, experience with existing buildings and precise execution. Planning and construction were completed within a few weeks – on time and with safety ensured.

Why photovoltaic systems on large roofs require construction expertise

Installing a PV system on a large roof is not a standard project. Load-bearing reserves, roof structure, logistics and work safety are crucial – as is maintaining operations during the construction phase. WALO performs structural calculations in-house, plans substructures itself and works according to the safety standards of primary construction trades. Our fitters are equipped and trained to the appropriate level, which is in fact above the industry average for traditional solar installers. “Large roofs are never just about modules,” explains Björn Faes. “You also have to consider structural engineering, construction processes and safety. If you are familiar with these construction principles, you can recognise risks early on and resolve them properly.”

WALO provides specific solutions for typical large roof challenges:

• Technical platforms: inverters and system components are mounted in an elevated position – storage areas remain usable
• Soundproof enclosures: customised for noise-critical locations
• BIM planning and drone surveying: precise recording and simulation before construction begins
• In-house metal construction workshop: individual substructures from a single source

From the potential analysis to commissioning and beyond

WALO provides end-to-end support for photovoltaic projects: from the potential analysis to the structural clarification and planning, all the way to the final system. Permits and funding clarifications at federal, cantonal or municipal level are also considered and taken care of. With 17 locations in Switzerland and around 2,600 specialists, WALO can also realise large projects quickly – around the clock if necessary. With its system and yield monitoring processes and maintenance packages for all-round worry-free operation, WALO remains active even after commissioning.

From an economic point of view, the greater the self-consumption and the roof area, the faster the system pays for itself. Currently, a ROI is often achieved at around five years based on a calculated service life of 20 years (depending on the project and subsidies).

What subsidies are available for photovoltaic systems?

PV systems on large roofs can be subsidised at various levels:

• Federal level: one-off remuneration for large installations
• Cantons: additional support programmes (varies from canton to canton)
• Municipalities: local renewable energy promotion programmes

WALO clarifies on a project-specific basis which subsidies can be applied for and handles the registration with the relevant authorities.

Your roof has potential – we will show you how much

WALO realises photovoltaic systems on roof areas from approx. 1,000 m² or where complex conditions require a particular level of experience (e.g. close to railways, special safety requirements). 

Keen to find out the potential of your roof? Our experts will analyse your building as part of a non-binding and easy-to-understand consultation process.