Solar panels · Sion

Photovoltaic solar panels in Sion: a guide for homeowners

Investing in solar energy in Sion increases the value of your property while supporting the objectives of the Sion region climate plan. This guide accompanies you through the energy transition of your home located at 515 meters above sea level.
Solar panels – Sion

Worked examples in Sion

Small project

CHF 9'800 – CHF 18'500

Typical project

CHF 18'100 – CHF 32'900

Large project

CHF 31'400 – CHF 55'800

Computed with our estimator for Sion (regional factor included), standard finish. Only the project size changes.

Cost split (typical project)

  • Labour : CHF 8'700 (35 %)
  • Materials : CHF 13'700 (55 %)
  • Other costs : CHF 2'500 (10 %)

Why and when to undertake these works in Sion

Sion benefits from a favorable annual global irradiation of approximately 1421 kWh/m². This data confirms the region's significant solar potential for sustainable electricity production.9 °C and heating needs based on heating degree days, optimizing your roof is a relevant strategy.

The Sion region climate plan actively encourages this energy transition to reduce overall energy consumption. By acting now, you benefit from optimal sunlight conditions while anticipating the evolution of the local real estate stock toward greater efficiency.

The timing is strategic to harmonize the installation with your thermal renovation projects. Taking advantage of a roof repair, for example, allows for optimal integration.7 °C and about 57 frost days per year, require a robust installation.

Anticipating your works helps prepare your home for greater future autonomy, aligned with the sustainability goals set for municipalities in the region such as Arbaz, Ayent, or Savièse, which are integrated into the joint climate planning.

Technical choices and options

The success of your photovoltaic installation relies on technical choices adapted to your structure. On average, a south-facing roof with a tilt of about 30 degrees allows for an interesting yield estimate. However, the quality of components and cell technology influence overall performance.

There are several quality levels, from standard panels to high-efficiency solutions designed for limited areas. It is essential to choose certified equipment capable of withstanding significant thermal variations between hot days and frost periods in the region.

In addition to the panels, energy management options are crucial. Adding a storage battery increases your self-consumption, which is particularly relevant if your consumption profile is high during the evening. Home automation also allows you to control your appliances based on instantaneous solar production.

Do not forget that the one-time federal remuneration via Pronovo reduces the initial investment, while your profitability will depend directly on the share of electricity that you consume on-site rather than feeding it into the grid.

The feasibility study must therefore integrate these technical parameters to maximize your return on investment.

Specifics of the local building stock and risks

The building stock in Sion presents specific challenges depending on the construction period. For older buildings, it is necessary to verify the load-bearing capacity of the roof structure before any installation, as the weight of solar panels must be supported without compromising structural safety.

If your home was built before 1990, increased vigilance is recommended regarding the potential presence of asbestos in certain roofing materials, which might require asbestos removal before installation.

Thermal insulation of the attic is another critical point : a well-insulated and ventilated roof is essential to avoid overheating of photovoltaic modules in summer, which reduces their electrical yield.

The electrical networks of older buildings may require upgrading to support solar electricity injection. It is therefore essential to assess the condition of your current electrical panel with a professional. Moreover, the geography of Sion, between the plain and the hillsides, involves variable exposures.

In sensitive hillside areas, specific requirements are set by the authorities to ensure harmonious aesthetic integration.

A well-designed installation must take into account the solidity of the roof and the durability of internal electrical connections to avoid premature damage linked to the extreme thermal constraints of Valais.

Authorizations and heritage

In Sion, the management of built heritage strongly influences photovoltaic projects. Although the ban on installing solar panels in the old town has been lifted, this remains subject to strict conditions. For buildings classified as degrees 1, 2, and 3, the rules remain very restrictive.

Buildings classified as degrees 1 or 2, of national or cantonal importance, generally have solar installations refused a priori. For degree 3, which corresponds to communal importance, a balancing of interests is conducted.

Buildings classified as degrees 4 and 4+ have better chances of obtaining authorization, provided that heritage integration requirements are met.

If your building is not classified but is located in a protected perimeter, such as the old town or certain villages and hamlets, panels are in principle allowable subject to a specific evaluation. Integration must be adequate, particularly in the medieval part.

Installation on flat-roof annexes visible from neighboring homes is generally prohibited. In sensitive hillside areas, increased requirements apply regarding color, surface, and regularity of shapes.

It is essential to contact the municipal urban planning department before any order to validate the conformity of your project, as each request is subject to an individual analysis.

Financial aid and taxation

Financial support for photovoltaic solar power is mainly based on the federal one-time remuneration (Pronovo). This aid helps to significantly reduce the amount of your initial investment.

To benefit from it, strict compliance with the order of steps is imperative: you must imperatively submit your application for support before starting work. Any installation started before the application could be refused the grant.

It is also recommended to check with your municipality in Sion, as some Valais municipalities offer additional premiums or specific local support in addition to federal aid.

Regarding taxation, the installation of photovoltaic panels is generally considered an energy-saving measure or ecological added value, which can influence the tax treatment of your investments. However, as rules evolve, it is advisable to carefully keep all invoices related to the installation.

These supporting documents are essential for your tax returns and to confirm that the work has been completed in compliance.

Remember that overall profitability will also depend on your ability to optimize your own consumption, as a sufficiently adapted rooftop installation is often only subject to simple notification to the competent authorities if it complies with integration standards.

Schedule: project workflow

The execution of a solar project in Sion requires rigorous planning to avoid the unforeseen. The first phase consists of a technical feasibility study and validation by urban planning services. Once authorizations are obtained and financial aid validated, the actual construction can begin.

It is preferable to avoid marked frost periods, which count for about 57 days per year, to facilitate roofing work and ensure the safety of workers on slopes. Months offering milder temperatures are therefore preferred for efficient execution without climatic delays.

The work generally begins with the installation of supports and fastening systems on the existing structure. Then, the panels are installed, followed by electrical connection work, including the installation of the inverter and the possible integration of a management system.

The last step is commissioning and conformity testing. This process must be coordinated to minimize inconvenience. Although the duration depends on the complexity of your roof, regular monitoring of steps ensures the conformity of the installation.

Once operational, the system will immediately produce electricity while respecting local requirements for landscape integration.

Frequent mistakes and checklist

To make your project a success, avoid some common mistakes. Never fail to check local urban planning rules before choosing the panel model, otherwise you might have to dismantle your installation.

Do not start any work before receiving confirmation for the Pronovo one-time remuneration, as you would lose your right to the aid. Avoid underestimating the condition of your roof: if it needs repairs, do them before installing the panels. Also, ensure your electrician is qualified for photovoltaic installations.

Checklist before requesting quotes : 1. Check with the Sion urban planning department whether your building is subject to specific heritage restrictions. 2. Have a health check of your roof and its thermal insulation performed by a professional. 3.

Analyze your annual electricity consumption to correctly size the power of your installation. 4. Request several comparative quotes detailing the components used and the guarantees offered. 5. Confirm that the chosen professional handles the grant application with Pronovo for you. 6.

Check the compatibility of your electrical panel for electricity injection. 7. Ensure that the visual integration of the panels meets the city's requirements.

Maintenance and durability

A well-maintained photovoltaic installation is a guarantee of longevity and constant performance. In the Sion region, significant climatic variations require an annual visual check, ideally in the spring.

Cleaning the panels may be necessary if an accumulation of dust or plant debris forms, so as not to reduce the cell yield. Use clean water and non-abrasive equipment.

Checking the mounting system and the condition of the inverters must be done by a professional, in accordance with manufacturer recommendations to ensure compliance with safety standards.

Durability also depends on the quality of the components chosen during the initial phase. Investing in certified equipment guarantees better resistance to Valais winter conditions. Remote monitoring via a management app allows for immediate detection of any production anomaly.

If an unexplained drop in yield is observed, call your installer for a thorough technical inspection. By following these simple maintenance tips, you protect your investment while maximizing your clean energy production over the long term.

A sustainable installation contributes directly to the valuation of your property on the Sion market.

Grants and subsidies

Canton

Solar PV — one-off payment (Valais)

Based on installed capacity; municipal premiums possible.

Federal one-off payment for PV; some Valais municipalities add premiums.

www.pronovo.ch

Check amounts and conditions with the provider before signing: apply before work starts in most cases.

Companies in the area

Evolium Technologies SA

1950 Sion · about 0 km

Valais-based company specializing in the manufacture and installation of modular, repairable solar storage batteries with a lifetime guarantee.

evolium.ch

AZ Electricité Sàrl

1950 Sion · about 0 km

AZ Electricité Sàrl, based in Sion, provides electrical installation, maintenance and repair services, as well as photovoltaic panel installation.

azelectricite.ch

Willy Bonvin Electricité SA

1950 Sion · about 0 km

Willy Bonvin Électricité SA is a Valais-based company specializing in electrical installations, repairs, and photovoltaic systems since 1973.

willy-bonvin-electricite.ch

OIKEN Solutions SA

1950 Sion · about 0 km

OIKEN Solutions SA is a company specializing in electrical installations, home automation, and photovoltaic solar energy solutions.

oiken.ch

Suggestions from the commercial register by distance and activity. Not an endorsement or partnership.

Frequently asked questions

Is solar energy allowed in the old town of Sion?

Yes, but under strict conditions. Each application is evaluated individually according to the building's degree of protection.

What aid is available for my installation?

You can benefit from the one-time federal remuneration via Pronovo. Also check with the municipality for possible local premiums.

Can I install panels on a flat roof in Sion?

Installation is generally prohibited on annexes visible from neighboring dwellings. A case-by-case analysis is necessary.

When should I submit my grant application?

Imperatively before starting work. Any installation started before the application may lead to a refusal.

What is the estimated yield of a roof in Sion?

For a well-oriented roof, the estimate is about 1250 kWh per kWp per year. This, however, depends strongly on your configuration.

Does the altitude of Sion (515 m) influence the material?

Yes, the equipment must withstand marked thermal amplitudes, notably the 57 frost days per year on average.

Do I have to declare my installation to the authorities?

Yes, an authorization request is necessary. In some cases, a simple notification is sufficient depending on integration rules.

Useful local data

Estimated solar yield — 1'250 kWh/kWc/an (toit ~30° sud, PR 0.8, estimation)

Source : Open-Meteo Historical Weather API (réanalyse ERA5, moyenne 2015-2024) · estimate

Altitude — 515 m

Source : swisstopo – service d'altitude (MNT)

Heating degree days — 2'737 Kj/an (20/12 °C)

Source : Open-Meteo Historical Weather API (réanalyse ERA5, moyenne 2015-2024)

Frost days — 57 jours/an

Source : Open-Meteo Historical Weather API (réanalyse ERA5, moyenne 2015-2024)

Solar irradiation — 1'421 kWh/m²/an (horizontal)

Source : Open-Meteo Historical Weather API (réanalyse ERA5, moyenne 2015-2024)

Winter design temperature — -8.7 °C (1er percentile des minimales)

Source : Open-Meteo Historical Weather API (réanalyse ERA5, moyenne 2015-2024)

Mean temperature — 11.9 °C

Source : Open-Meteo Historical Weather API (réanalyse ERA5, moyenne 2015-2024)

Energy policy

  • Note : Le Plan climat de Sion région regroupe les communes d’Arbaz, Ayent, Grimisuat, Saint-Léonard, Savièse, Sion et Veysonnaz.
  • Targets : Par leur politique énergétique communale, les communes du Plan climat de Sion région souhaitent avoir un impact direct sur la diminution de la consommation globale d’énergie et le développement des énergies renouvelables. Elles entendent notamment agir sur l’amélioration de l’efficacité énergétique des bâtiments communaux, des installations techniques et des véhicules, ou encore la modernisation ou l’extinction de l’éclairage public.
  • Climate plan : Plan climat de Sion région

Source : Sion.ch

Heritage

  • Solar / facade constraints : À Sion, l'interdiction de panneaux solaires en vieille ville a été levée, mais à de strictes conditions. Elle reste en principe en vigueur pour les bâtiments classés de degrés 1, 2 et 3. Pour les bâtiments non classés mais situés dans un périmètre de protection patrimoniale (vieille ville, village ou hameaux), les panneaux solaires sont à priori autorisables, pour autant que de très strictes conditions soient respectées. Chaque demande est évaluée séparément. La pose de panneaux solaires sur les annexes à toit plat et visibles d'en haut par les habitations voisines est en principe interdite. Pour les bâtiments classés à titre individuel à l'inventaire du patrimoine bâti, les installations solaires sont a priori non autorisables pour les degrés de classement 1 et 2 (importance nationale et cantonale). Le degré 3 (importance communale) donnera lieu à une pesée d’intérêt. Enfin, pour les degrés de classement 4+ et 4 (importance communale), les installations solaires sont à priori autorisables, là encore moyennant le respect de strictes conditions. Les installations photovoltaïques doivent s’intégrer de manière adéquate au patrimoine de la ville, surtout dans sa partie médiévale. Pour les bâtiments situés en zone de coteau sensible, des exigences accrues sont fixées afin d'assurer la meilleure intégration possible, concernant notamment la couleur des panneaux, leur surface et la régularité de leurs formes.
  • Protected areas : ✓

Source : batimag.ch

Other works in Sion

Solar panels in nearby towns