Frequently asked questions about photovoltaics

Questions

On which buildings are PV systems suitable?

PV systems can be installed on most building roofs. Roof surfaces that are used for a PV system should fulfil the following requirements:

approx. 15 m² Usable area
For pitched roofs: Orientation in the range between east (north-east) to west (north-west)
relatively unshaded
Roof condition ok / no renovation pending
Construction of a PV system is permitted

PV systems can be installed on almost all existing roof types and shapes. One exception is fibre cement roofs containing asbestos. These should be renovated beforehand. Another exception is plain tile roofs with a single covering. The installation of PV modules is generally difficult here. Due to the shape of the roof and aesthetic considerations, installation on tent and hip roofs is sometimes rather unsuitable.

With certain roof constructions, the statics of the roof can also be critical, taking into account the additional load of the photovoltaic system (including ballasting). In case of doubt, this should be checked in advance by a structural engineer.

In certain zones and areas, there are also legal restrictions on the construction of a PV system. The exact restrictions vary from canton to canton (see also the information under "Planning permission").

Will the roof be affected by the construction of a PV system?

If planned and installed correctly, a PV system will not impair the function or service life of the roof.

For certain roof types, such as standing seam roofs, PV systems can only be installed under certain conditions and with mounting systems designed for this purpose. In these cases, the PV system should always be installed in consultation with the roof manufacturer.

For flat roofs, a structural analysis should generally be obtained from a qualified structural engineer before the construction of a PV system, taking into account the additional load of the PV system.

It is also advisable to have the roof inspected by a specialist (roofer, plumber, carpenter, etc.) to check and document the condition of the roof before the PV system is installed. Pending renovation work on the roof should be carried out before a PV system is installed.

How do I proceed?

The following 5-step process has proven successful for the planning and construction of a PV system:

1. initial consultation

The basic suitability of a building can often already be assessed during an initial inspection. The objectives (size, type, design, etc.) of the PV system can also be determined. In addition, questions can be raised and clarified during and after the initial meeting.

For smaller and simpler projects (EFH, MFH), binding offers for a PV system can often already be prepared based on the information and photos taken during the initial inspection (→ directly to point 4).

2. feasibility study

For larger projects, it is advisable to first carry out a feasibility study as a basis for decision-making. An initial rough concept of the PV system is drawn up and the PV system is analysed using simulation tools with regard to electricity yield, self-consumption share, costs, economic efficiency, loads, etc.). This allows the feasibility, costs and profitability of the PV system to be estimated relatively accurately.

3. investment concept

Once the feasibility study has been completed, the technical system concept can be finalised, including module layout, installation type, cable routing, wiring, component selection and safety equipment (fire, lightning and overvoltage protection, fall protection). Binding, precise and comparable quotations can then be drawn up from this.

4. request for quotation

The next step is to obtain several current competitive offers on the market for the delivery and installation of the PV system (including all components). The offers must be compared in terms of costs and scope of delivery (products and services). This may require adjustments.

The contract is awarded to the bidder with the most economically favourable offer after the bids have been evaluated. A contract for work and labour is concluded with this bidder.

5. realisation

The implementation phase begins with the submission of the necessary registrations and applications (connection application, installation notification, construction notification, registration for one-off remuneration). In addition, a professional inspection of the roof and, if necessary, a structural analysis should be obtained before the PV system is installed. Before and during the construction of the PV system, care must be taken to ensure adequate occupational safety and working conditions in line with industry standards, as well as careful execution in accordance with the offer. Supervision of the construction work and technical inspections by an independent PV planner can also be useful here.

Do I need a building licence?

In most cases, there is now only a notification requirement for the construction of a PV system. Exceptions are buildings in protection zones (core, townscape and monument protection zones), historic town centres, on cultural and natural monuments of cantonal or national importance, etc. In case of doubt, the conditions should be clarified in advance with the responsible authority (e.g. cantonal monument preservation office).

Is a photovoltaic system profitable?

The profitability of a PV system depends heavily on the proportion of self-consumption of the solar power (i.e. the proportion of the electricity produced that is consumed on site; see also the section "What is the significance of self-consumption?" below) and the local electricity and feed-in tariffs. In addition, larger PV systems (with corresponding electricity demand) achieve lower specific costs (costs per unit of installed capacity), as the fixed costs of the system are less significant and economies of scale are achieved.

A typical PV system on a detached house with a size of approx. 5 to 15 kW_pwhich achieves a self-consumption rate of 30% usually pays for itself (based on today's tariffs) within a period of approx. 15 to 20 years. After that, the system supplies electricity for a further 10 to 15 years.

With larger systems, a higher proportion of self-consumption and/or higher electricity and feed-in tariffs, a PV system can pay for itself within around 10 to 15 years.

How much is the subsidy?

The subsidy (one-off payment) for a PV system from the federal government depends on the size and type of system. The one-off payment currently covers around 10-20% of the investment costs of a PV system. The currently valid subsidies can be found at https://pronovo.ch be calculated.

PV systems are an energy-related measure in construction and can generally be claimed as a property expense for existing buildings (even if they increase the value), resulting in tax savings (corresponding to the marginal tax rate).

Some municipalities also subsidise PV systems. Please enquire directly with the responsible office in your municipality.

How much is the feed-in tariff for solar power?

The feed-in tariff is set by the distribution system operator (DSO) and varies from DSO to DSO. It is also reduced in many cases from a certain system size (e.g. from 30, 100, 3000 kVA). An overview of the current feed-in tariffs for all municipalities in Switzerland can be found at https://www.vese.ch/pvtarif.

Typically, the feed-in tariffs are around 8 to 16 cents/kWh. There is usually an additional payment for the guarantee of origin. This is between 2 and 3 cents/kWh and must be transferred (sold) separately to a buyer (often also the VBN).

From 2026, new minimum feed-in tariffs will apply, which depend on the type and size of the system. These will support system owners if the feed-in tariff becomes very low. For systems with self-consumption and a size of up to 30 kWp, the minimum remuneration is 6 cents/kWh. It decreases with increasing size (up to a maximum of 150 kWp).

What is the significance of the self-consumption share?

The self-consumption share (also: self-consumption rate; self-consumption level) indicates what proportion of the solar power produced is consumed on site (i.e. in the building) before it flows into the electricity grid. The self-consumption rate is usually averaged over the year.

As the electricity tariff for grid electricity is higher than the feed-in tariff for solar power, self-consumption of solar power is more economically viable than feeding it into the grid.

The proportion of self-consumption depends heavily on the size of the system (relative to electricity consumption) and the consumption profile over time. Smaller PV systems achieve higher self-consumption shares. Self-consumption can also be increased to a certain extent through appropriate consumer behaviour by using energy-intensive consumers such as washing machines, dryers or electric vehicles to use the solar power generated during daylight and sunshine.

Furthermore, larger and flexible consumers such as electrically heated hot water boilers or heat pumps can be switched on depending on the yield, although this requires a corresponding additional control system. A further increase in the proportion of self-consumption can be achieved with a battery storage system. However, the economic viability of batteries is not given in most cases today (see also section "Does battery storage make sense?").

What is the degree of self-sufficiency?

The degree of self-sufficiency (also: self-sufficiency rate; degree of self-sufficiency) of a PV system indicates the proportion of electricity consumption that is covered by self-produced solar power. The degree of self-sufficiency is usually calculated as an average for the year.

The degree of self-sufficiency depends, among other things, on the size of the system. A relatively high degree of self-sufficiency can be achieved with a relatively large PV system. However, complete self-sufficiency (independence from electricity drawn from the grid) is almost impossible to achieve and would generally involve very high costs. A connection to the electricity grid is also still required in most cases in order to sell surplus solar power.

Does battery storage make sense?

Battery storage systems make it possible to store some of the solar power produced during the day and consume it after sunset or when there is insufficient solar power production, thereby reducing the amount of grid electricity required. This allows the self-consumption share of a PV system and the degree of self-sufficiency to be significantly increased.

However, the resulting savings in grid consumption must be weighed against the additional costs of battery storage. This shows that the costs of a battery storage system are usually higher than the electricity cost savings achieved. For this reason, battery storage systems are generally not economical today. However, if the primary aim is to achieve the highest possible degree of self-sufficiency from the electricity grid, battery storage systems can make a major contribution to this.

Do solar systems work in the event of a power failure?

PV systems are normally grid-connected. This means that the system is dependent on the power grid. If the power grid fails, the PV system (and any battery storage) switches off automatically. However, there are solutions for PV systems with emergency power supply capability. Our information sheet "PV systems with emergency power function" PDF shows which PV system configurations are capable of emergency power supply and which common systems are available on the market.

What is a ZEV?

ZEV stands for "association for own consumption" and refers to a community of PV system operators (usually property owners) and electricity consumers (typically tenants).

How does a ZEV work?

The solar power generated within a ZEV is, as far as possible, consumed directly in the ZEV and is therefore considered to be self-consumption (see section above). This reduces the amount of electricity purchased from the grid accordingly.
Surplus solar power is fed into the public grid.
If not enough solar power is produced in the ZEV, electricity is drawn from the grid.
The pricing for solar power in the ZEV is customised. As a rule, the price for solar power lies between the tariff for grid electricity and the production costs of solar power. This creates a win-win situation for PV system operators and consumers: the system operator receives sufficient remuneration for the solar power, while electricity consumers realise savings compared to grid electricity.

The perimeter for ZEVs has been extended since 1 January 2025. A ZEV is now not just limited to one building, but can also be set up to include other consumers at the same grid connection point (i.e. possibly several neighbouring buildings). In addition, new electricity meters no longer need to be installed for ZEV billing - billing can now be carried out directly using the measurement data from the grid operator's smart meters.

Do you have any further questions?

Get in touch with usif you have any further questions, as well as for a non-binding discussion about the possibilities of photovoltaics.