Solar thermal in Sierre: A practical guide for homeowners

Sierre benefits from remarkable sunshine, with a global horizontal irradiation of 1451 kWh/m²/year, which is a major asset for solar thermal energy. The city, awarded the 'Energy City Gold' label, actively encourages the transition to renewable systems.

3 °C and significant heating needs marked by 2988 heating degree days, optimizing hot water production via solar energy helps reduce dependency on fossil fuels. Undertaking this work is ideal at the time of replacing your old heating system or during a comprehensive energy renovation to maximize efficiency gains.

The local climate, characterized by 72 frost days per year and a winter design temperature of -10 °C, requires a robust installation. By using the radiation captured during less cold periods, you lighten the load on your main boiler.

This strategy fits perfectly into the energy policy program and action plan 2024–2027 of Sierre, ensuring that your efforts align with cantonal and communal climate goals.

The sizing of your solar thermal installation depends on your actual domestic hot water needs. Solar thermal collectors generally cover a large part of summer hot water. There are mainly two types of technologies: flat plate collectors and evacuated tube collectors.

Flat plate collectors are often favored for their robustness and aesthetic integration, while vacuum tubes offer better performance during periods of low sunshine or extreme cold. The choice between these options must take into account the slope of your roof and its orientation.

Combining solar collectors with other systems, such as a heat pump, requires a rigorous sizing study. This integrated approach allows optimizing the solar coverage rate throughout the year.

In addition to the collector technology, the capacity of the storage tank must be calculated to match your daily consumption, thus avoiding unnecessary heat losses.

Working with certified installers allows selecting compatible components that ensure the longevity of your investment and consistent performance in the face of the region's thermal variations.

Sierre's building stock is varied, ranging from old structures to modern buildings meeting current standards. For houses built before 1990, it is imperative to identify the potential presence of asbestos in roof elements or insulation before starting the installation of panels.

The quality of the overall thermal insulation directly influences the relevance of solar thermal energy. A poorly insulated house will quickly lose the generated heat, which makes the energy renovation of the building envelope a priority over the installation of collectors.

Internal water and heating distribution networks must also be evaluated to ensure they can withstand the temperature rise from solar energy. In historic buildings or those located in sensitive areas, the exterior visual aspect is a constraint to anticipate.

A preliminary technical assessment allows verifying the strength of the frame to support the load of solar collectors. In Sierre, the climate with its freeze cycles requires particular vigilance on the sealing of roof penetrations to prevent water infiltration, a source of long-term damage.

Before any intervention on your roof, it is necessary to consult the municipal services of Sierre to validate the compliance of your project.

Although the municipality actively supports sustainable development, certain protected sectors or buildings of heritage interest may be subject to specific restrictions regarding the installation of solar equipment on facades or roofs.

The standard procedure often involves filing a simplified building permit application with the competent authority.

It is highly recommended to contact the urban planning department of Sierre at the beginning of your reflections. They will be able to advise you on local rules, particularly regarding the visual integration of collectors. Never start work without receiving a formal authorization if required by communal regulations.

Keep in mind that these rules aim to preserve the cityscape while encouraging energy transition. Checking with the municipality protects you legally and avoids litigation or requests for subsequent dismantling due to non-compliant installation.

The encouragement for solar thermal installations in Valais is realized through the cantonal program. To benefit from this aid, it is essential to follow the sequence of steps: you must submit your grant application before the actual start of work.

The amounts are granted according to the scale in force at the time of the request. You can consult the details of the conditions on the official website of The Buildings Program to obtain all relevant information on the eligibility of your project.

In addition to direct subsidies, certain costs related to energy renovation work may be tax-deductible. It is recommended to keep all invoices and the approval file for the aid. The aids aim to reduce the initial investment cost, making the solar solution more accessible.

As conditions can change, systematically check for updates on official websites before finalizing your quote. Ensure that your installer has a good knowledge of these administrative procedures to facilitate the preparation of your file.

The planning of a solar construction site begins with a phase of in-depth technical study, followed by the submission of the communal authorization request. Once the authorizations are obtained and the subsidy application is validated, the components can be ordered.

The ideal season to carry out roofing work is the temperate period, avoiding as much as possible the months of extreme cold, because the 72 frost days per year in Sierre can complicate the handling of materials and the safety of workers on the roofs.

The actual site begins with the installation of the support structure and thermal collectors. Then come the hydraulic connection works towards the technical room, where the storage and regulation system is located.

Commissioning includes a series of pressure tests and heat transfer fluid circulation tests to ensure the absence of leaks and optimize performance. Finally, the site ends with a fine-tuning phase of the installation and an explanation of the operation to the user, ensuring effective use of your new solar system.

Never neglect the compatibility of your future system with your current boiler. Ensure that your project is sized according to your actual needs and not on an overly optimistic estimate. Systematically check the strength of your roof before incurring costs.

Do not sign any quote before receiving assurance that the financial aid has been requested according to the official procedure. Avoid installations without a serious preliminary thermal study. Ensure that the chosen company has the required certifications for solar installations.

Also check that the quote includes the commissioning and training costs for using the system. Finally, make sure you have clarified access to the construction site to avoid any unforeseen additional costs.

The durability of your solar thermal installation directly depends on regular maintenance performed by professionals. An annual or biennial check is recommended to verify the level and quality of the heat transfer fluid, as well as the condition of the electronic control components.

Replacing wear parts, such as circulation pumps or seals, ensures constant performance over several decades. Occasional cleaning of the collectors, although often handled by rainwater, may be necessary in areas with significant dust deposits.

A well-maintained installation is the guarantee of securing your investment. Regularly monitor the indicators on your dashboard to detect any temperature anomalies.

By following the manufacturer's recommendations and calling on a qualified service provider for checks, you maximize the lifespan of the system and the overall energy yield.

Consider this maintenance as a normal step in the life cycle of your hot water production equipment, essential to maintain the ecological and economic benefits promised initially.