Solar glossary: terms from A to Z

Annual electricity consumption is the amount of electricity your household or business draws in a year. You can find it on your electricity bill. It is a key factor for sizing the solar system and battery storage appropriately.

See also: Kilowatt-hour (kWh).

The annual yield is the amount of electricity a solar system generates in one year, expressed in kilowatt-hours. It depends on location, orientation, pitch, and shading. For comparing systems, the specific yield in kWh per kWp is used.

See also: Kilowatt peak (kWp), Shading. In the guide: Calculating a solar system.

Backup power is electricity during a grid outage. An ordinary solar system switches off for safety reasons in that case. Backup power requires battery storage and an inverter designed for it, as well as a changeover switch from the grid.

See also: Battery storage, Hybrid inverter.

A battery storage unit stores solar electricity that you do not need at the moment and releases it later. This allows you to use more of your own roof’s electricity yourself.

See also: Self-sufficiency rate, Hybrid inverter. In the guide: Advantages and disadvantages of battery storage.

A bidirectional meter separately measures how much electricity you draw from the grid and how much you feed in. The grid operator installs it when connecting the solar system.

See also: Grid operator.

Some cantons and municipalities use the term building notification (German: Bauanzeige) for the notification of a construction project that does not require an ordinary building permit. For solar systems, this generally means the notification procedure. Your municipality or canton determines the form and the deadline.

See also: Notification procedure, Building permit.

The building permit (German: Baubewilligung) is the official authorisation for a construction project. For most solar systems on roofs, the notification procedure is sufficient. A building permit remains necessary, among other things, for cultural and natural monuments of cantonal or national importance (Spatial Planning Act, Art. 18a).

See also: Notification procedure, Townscape protection.

The cell efficiency is the efficiency of the individual solar cell. It is slightly higher than the module efficiency because the frame and gaps in the module do not generate electricity.

See also: Module efficiency. In the guide: Solar modules and solar panels.

The CO₂ balance compares how much greenhouse gas the manufacture of a solar system causes and how much its electricity avoids during operation.

Commissioning is the point in time when the completed and inspected system is connected to the grid. The date determines which subsidy rate applies. You apply for the KLEIV afterwards.

See also: KLEIV, Subsidy application.

Condominium ownership (German: Stockwerkeigentum) is the Swiss form of flat ownership: co-ownership of the building with an exclusive right to one’s own unit. The community of owners decides on a solar system on the shared roof.

See also: ZEV (association for self-consumption). In the guide: Association for self-consumption (ZEV).

In contracting, a third party plans, pays for, and operates the solar system on your roof. You receive the electricity at an agreed price and do not invest yourself.

In the guide: Financing a photovoltaic system.

Degradation is the gradual loss of performance of solar modules over the years. Manufacturers guarantee in the performance warranty how much performance will remain at least after a certain period.

See also: Module efficiency. In the guide: Solar modules and solar panels.

In direct marketing, you do not sell your solar power to the local grid operator, but through a service provider on the electricity market. This is mainly relevant for larger systems.

See also: Feed-in tariff (Rückliefertarif).

The electric utility (German: Elektrizitätswerk, EW) is the local electricity supplier. It often also operates the distribution grid and is therefore your point of contact for grid connection and the feed-in tariff.

See also: Grid operator, Feed-in tariff (Rückliefertarif).

A façade system carries the solar modules on the wall of the building. Because of the steep angle, it supplies a comparatively large share of its electricity in winter. For systems with a tilt of 75 degrees or more, the federal government may pay a tilt-angle bonus (Energy Promotion Ordinance, as of 08.10.2026).

See also: Roof pitch, One-off payment (EIV). In the guide: Subsidies for solar systems.

The feed-in tariff (German: Rückliefertarif) is the price the grid operator pays you for solar electricity fed into the grid. It is also called feed-in remuneration (Einspeisevergütung). The tariff varies depending on the grid operator.

See also: Reference market price, Minimum remuneration, Guarantee of origin (HKN). In the guide: Feed-in remuneration in Switzerland.

On flat roofs, the modules are mounted on racks, tilted slightly towards the south or paired towards the east and west. The racks are often ballasted rather than screwed in to keep the roof surface watertight.

See also: Mounting structure.

With full feed-in, all solar electricity flows into the grid; you do not use any of it yourself. For such systems, there is the high one-off payment (HEIV).

See also: HEIV, Surplus feed-in.

GEAK is the cantonal building energy certificate (German: Gebäudeenergieausweis der Kantone). It rates the energy efficiency of a building in classes from A to G. GEAK Plus also includes an advisory report with renovation proposals; some subsidy programmes require it.

See also: Minergie.

GREIV stands for the one-off payment for large photovoltaic systems with a capacity of 100 kW or more.

See also: One-off payment (EIV), KLEIV, HEIV. In the guide: Pronovo subsidy.

The grid operator runs the local power grid. It checks the connection of your solar system, installs the meter, and remunerates the electricity you feed in.

See also: Electric utility (EW), Technical connection request (TAG), Feed-in tariff (Rückliefertarif).

The guarantee of origin (German: Herkunftsnachweis, HKN) certifies where each kilowatt-hour of electricity comes from. Pronovo operates the system of guarantees of origin. Many suppliers pay a surcharge on top of the feed-in tariff for guarantees from solar power.

See also: Pronovo, Feed-in tariff (Rückliefertarif). In the guide: Feed-in remuneration in Switzerland.

HEIV stands for the high one-off payment. It applies to systems from 2 kW to 149.99 kW without self-consumption that feed their electricity into the grid in full for at least 20 years.

See also: One-off payment (EIV), Full feed-in. In the guide: Pronovo subsidy.

A hybrid inverter is an inverter to which both the solar modules and a battery storage unit are connected. A second device for the battery is not required.

See also: Battery storage. In the guide: Inverters for photovoltaics.

Imputed rental value (German: Eigenmietwert) is a notional income on which owners pay tax for the home they live in themselves. In return, maintenance costs are deductible, as are, for existing buildings, investments in a solar system. The reform of residential property taxation abolishes the imputed rental value; according to the Federal Council’s media release of 01.04.2026, it enters into force on 01.01.2029.

See also: Property maintenance costs. In the guide: Saving taxes with photovoltaics.

With the installation notice (German: Installationsanzeige), an electrical installation is reported to the grid operator before work begins (Low-Voltage Installation Ordinance). For a solar system, your specialist installer submits it.

See also: Technical connection request (TAG), Grid operator.

The kilowatt-hour, abbreviated kWh, is the unit for quantities of electricity: A device with one kilowatt of power consumes one kilowatt-hour in one hour. Yield, consumption and tariffs are stated in kWh.

See also: Kilowatt peak (kWp).

Kilowatt peak, abbreviated kWp, is the rated power of a solar system under defined test conditions. This specification makes systems comparable; in operation, the actual power is usually lower.

See also: Kilowatt-hour (kWh), Annual yield.

KLEIV stands for the one-off payment for small photovoltaic systems with an output of at least 2 kW but less than 100 kW. For most systems on residential buildings, this is the appropriate subsidy route. You submit the application after commissioning.

See also: One-off payment (EIV), GREIV, Commissioning. In the guide: Pronovo subsidy.

In a local electricity community (German: lokale Elektrizitätsgemeinschaft, LEG), producers and consumers from the surrounding area exchange solar power via the public grid. This form has existed since early 2026.

See also: ZEV (association for self-consumption), vZEV (virtual ZEV), Neighbourhood electricity. In the guide: Association for self-consumption (ZEV).

Minergie is a Swiss building standard for energy-efficient buildings with high living comfort. For new builds to Minergie standards, on-site electricity generation is a requirement, typically achieved through photovoltaics.

See also: GEAK.

The minimum remuneration is the statutory lower limit for the remuneration of solar electricity fed in from systems up to 150 kW. It applies when the reference market price falls below this level. For systems up to 30 kW, it amounts to 6 Rp./kWh (Energy Ordinance, as of 13.07.2026).

See also: Reference market price, Feed-in tariff (Rückliefertarif). In the guide: Feed-in remuneration in Switzerland.

The module efficiency indicates what proportion of the incoming sunlight a solar module converts into electricity. The higher it is, the more output fits on the same roof area.

See also: Cell efficiency, Degradation. In the guide: Solar modules and solar panels.

The mounting structure is the mounting system made of hooks, rails and clamps that connects the modules to the roof. It must withstand the wind and snow loads at the location.

See also: Roof-mounted system, Flat-roof system.

Neighbourhood electricity (German: Quartierstrom) is not an official term. It refers to solar power generated in the neighbourhood and consumed there. Legally, this is done through a ZEV, a vZEV or a LEG.

See also: ZEV (association for self-consumption), vZEV (virtual ZEV), LEG (local electricity community). In the guide: Association for self-consumption (ZEV).

In the notification procedure (German: Meldeverfahren), you report a solar system to the municipality or the canton instead of applying for a building permit. It applies to sufficiently adapted solar systems on roofs in building and agricultural zones (Spatial Planning Act, Art. 18a). The form and deadlines vary by canton.

See also: Building permit, Building notification, Townscape protection.

Many electricity utilities charge different rates depending on the time of day: a higher peak rate during the day and a lower off-peak rate at night and often on weekends. The utility determines the exact times. For calculating your solar system, what matters is which tariff the self-consumed solar power replaces.

See also: Electric utility (EW), Self-consumption.

The one-off payment (German: Einmalvergütung, EIV) is the federal subsidy for photovoltaic systems: a single contribution towards the investment, processed through Pronovo. It comes in three forms: KLEIV, GREIV and HEIV.

See also: KLEIV, GREIV, HEIV, Pronovo. In the guide: Pronovo subsidy.

Partial shading occurs when a chimney, dormer, tree, or neighbouring building shades part of the modules for a period of time. Because modules are connected in series, even a small shadow can reduce the yield of the entire string. Power optimisers or a clever wiring configuration mitigate this effect.

See also: Shading, Power optimiser.

The payback period ends when the savings and income from a solar system have covered the investment. How long this takes depends on price, subsidy, self-consumption and feed-in tariff.

See also: Return. In the guide: Is a photovoltaic system worthwhile?.

Photovoltaics, abbreviated PV, means the direct conversion of sunlight into electricity using solar cells. A photovoltaic system consists of solar modules, inverter, mounting structure and meter.

See also: Solar thermal energy, Kilowatt peak (kWp). In the guide: Guide to photovoltaic systems.

A power optimiser is a small device attached to an individual solar module. It ensures that a shaded or weaker module slows down the other modules in the string less.

See also: Partial shading. In the guide: Inverters for photovoltaics.

Pronovo is the body commissioned by the federal government to process subsidies for solar systems. It reviews applications for the one-off payment, pays out the contributions and manages the system of guarantees of origin.

See also: One-off payment (EIV), Guarantee of origin (HKN). In the guide: Pronovo subsidy.

Property maintenance costs are the costs of maintaining a building that owners can deduct in their tax return. For existing buildings held as private assets, investments in energy saving are treated the same way, for example in a photovoltaic system. Your canton regulates the details.

See also: Imputed rental value. In the guide: Saving taxes with photovoltaics.

“Die Solarprofis” is a quality label of the industry association Swissolar for vetted specialist companies. Companies with the label meet additional admission requirements and are checked against defined criteria.

See also: Swissolar. In the guide: Swissolar and the “Die Solarprofis” label.

The reference market price is the market price for solar power averaged over a quarter. The Swiss Federal Office of Energy calculates it and publishes it after the end of the quarter. Since 2026, the remuneration for fed-in electricity has been based on this price unless the grid operator and the producer agree otherwise.

See also: Minimum remuneration, Feed-in tariff (Rückliefertarif). In the guide: Feed-in remuneration in Switzerland.

The return relates the annual profit of a solar system to the investment. The profit results from saved grid electricity and remuneration, minus costs for operation and maintenance.

See also: Payback period. In the guide: Is a photovoltaic system worthwhile?.

In an integrated roof system, the solar modules replace the roof covering and form the roof surface themselves. This option is primarily considered for new builds and roof renovations. In terms of subsidies, it is classified as an integrated system.

See also: Roof-mounted system.

In a roof-mounted system, the solar modules are mounted on a mounting structure above the existing roof surface. This is the usual construction form for existing roofs. In terms of subsidy, it is considered an attached system.

See also: Roof-integrated system, Mounting structure.

The roof pitch is the angle of the roof relative to the horizontal. Together with the orientation, it determines how much sunlight hits the modules and how the yield is distributed over the year. Steeper surfaces produce proportionally more in winter.

See also: Annual yield, Façade system. In the guide: Calculating a solar system.

Self-consumption is the solar power you use directly in your own building. Each self-consumed kilowatt-hour replaces electricity from the grid and is therefore generally worth more than one fed into the grid.

See also: Self-sufficiency rate, Surplus feed-in. In the guide: Solar power from your own roof.

The self-sufficiency rate indicates what proportion of your electricity consumption you cover with your own solar power. Battery storage increases it because it stores solar power for the evening and night.

See also: Self-consumption, Battery storage.

Shading means any shadow falling on the solar modules, for example from mountains, trees or buildings. It reduces the yield and is taken into account in planning with a simulation.

See also: Partial shading, Annual yield.

Solar thermal energy uses sunlight for heat instead of electricity: solar collectors heat water for hot water and heating.

See also: Photovoltaics. In the guide: Solar collectors.

With a subsidy application (German: Fördergesuch) you apply for a contribution: the one-off payment from Pronovo, further contributions from the canton, the municipality or the energy supplier. Some programmes require the application before construction begins.

See also: One-off payment (EIV), Pronovo. In the guide: Subsidies for solar systems.

Surge protection diverts brief voltage spikes, for example from a nearby lightning strike. This protects the inverter and the house installation.

With surplus feed-in, you use the solar power yourself first. Only what remains flows into the grid and is remunerated. This is the norm for systems on residential buildings.

See also: Full feed-in, Self-consumption, Feed-in tariff (Rückliefertarif). In the guide: Feed-in remuneration in Switzerland.

Swissolar is the industry association for solar energy in Switzerland. All specialist installers in our partner network are members of Swissolar.

See also: Quality label “Die Solarprofis”. In the guide: Swissolar and the “Die Solarprofis” label.

With the technical connection request (German: technisches Anschlussgesuch, TAG), your specialist installer applies to the grid operator for connection of the solar system to the electricity grid. The grid operator checks whether the grid can absorb the feed-in. The request is submitted before construction.

See also: Grid operator, Installation notice.

The temperature coefficient indicates how much the output of a solar module decreases as it gets warmer. The lower the value, the less the module loses on hot days.

See also: Module efficiency. In the guide: Solar modules and solar panels.

Townscape protection (German: Ortsbildschutz) preserves the appearance of historic village and town centres. In protected townscapes and on listed buildings, stricter rules apply to solar systems; a building permit is often required there instead of a notification.

See also: Building permit, Notification procedure.

vZEV stands for virtual association for self-consumption (German: virtueller Zusammenschluss zum Eigenverbrauch). Since 2025, several parties can join together without building their own lines: they use the grid operator’s connection lines and meters.

See also: ZEV (association for self-consumption), LEG (local electricity community). In the guide: Association for self-consumption (ZEV).

In an association for self-consumption (German: Zusammenschluss zum Eigenverbrauch, ZEV), several parties jointly use the solar power from their own roof, for example the flats in an apartment building. They appear to the grid operator as a single customer.

See also: vZEV (virtual ZEV), LEG (local electricity community), Condominium ownership. In the guide: Association for self-consumption (ZEV).