Solar glossary: 65 photovoltaic terms explained

This glossary is built for looking up, not reading through. If a term appears in a quote, a tariff sheet or a consultation that means nothing to you: look here, understand it in two sentences, read on. Whoever prefers to learn in order starts with the Solar guide with chapter 1.

A

AC (alternating current) — The type of current that comes out of your sockets and with which all household appliances work. Solar modules deliver direct current (see DC); the translation is done by the inverter.

Acceptance obligation — The legal obligation of the grid operator to accept and remunerate the offered solar power from your system. What it includes and what it does not: Acceptance obligation for solar power.

Amortisation — The point in time from which the saved electricity costs and the remunerations have covered the investment. Seriously, it can only be specified as a range, because it depends on consumption, tariffs and electricity price development – distrust is appropriate if someone promises an exact year.

Degree of self-sufficiency — The share of your electricity consumption covered by your own system. Not to be confused with the self-consumption quota (see there) – for money, the quota is usually more important.

B

Battery storage — Stores the midday surplus and releases it again in the evening. A daily storage, not a seasonal storage: it cannot save summer power for the winter. The complete overview: Home battery Switzerland.

Building permit — For most solar systems on suitable roofs, none is needed – the notification procedure (see there) is sufficient. Exceptions mainly concern protection zones and special objects: Building permit in the Canton of Zurich.

Purchase tariff — What you pay per kilowatt hour from the grid. It consists of three parts: energy, grid usage and levies – and that is exactly why self-consumed solar power is so valuable: it saves all three.

Bidirectional charging — EV charging in both directions: the car can also feed power back into the house. Technically on the rise, but not yet a broad standard – vehicle, wallbox and billing must fit together.

D

DC (direct current) — The type of current generated by solar modules and with which batteries work. For the sockets, the inverter translates it into AC; how batteries are connected on the DC or AC side: DC and AC coupling.

Degradation — The slow, age-related performance loss of solar modules over the decades. Normal and planned for – a sudden drop in yield is something else: Degradation of solar modules.

E

Self-consumption — The solar power that you use yourself at the moment of production, instead of feeding it in. The economic core of every system – simply explained in chapter 6.

Self-consumption quota — The share of your production that you consume yourself. The most important monetary key figure of the system; how you increase it: Optimise self-consumption.

One-off feed-in incentive (EIV) — The one-off incentive contribution of the federal government to your system, paid out after commissioning via Pronovo. The most important incentive instrument in Switzerland: One-off feed-in incentive in detail.

One-off feed-in incentive, large (GREIV) — The variant of the one-off feed-in incentive for large systems, for example on business or apartment building roofs. Unlike with the small one-off feed-in incentive, the application to Pronovo can be submitted before construction, which makes financing more plannable. Where the limit lies and what applies: One-off feed-in incentive in detail.

One-off feed-in incentive, small (KLEIV) — The one-off feed-in incentive for smaller systems, i.e. the normal case for a single-family home. The application is made via Pronovo after commissioning; the paperwork is usually taken care of by the installer. Details: Pronovo registration.

Feed-in remuneration — The term common in Germany for the remuneration of fed-in solar power. In Switzerland this is called feed-in or feed-in tariff (see there); the one-off investment aid from the federal government is the one-off feed-in incentive (EIV). Anyone searching for «Einspeisevergütung Schweiz» usually means one of the two.

ElCom — The independent regulatory authority of the federal government for the electricity market. It monitors tariffs and decides on disputes – for instance between system owners and grid operators.

Utility (EW) — Your local power and grid operator – in the region for instance ewz, EKZ or Stadtwerk Winterthur. The utility is responsible for connection, meter and the remuneration of your fed-in power.

Energy management system (EMS) — The control centre that automatically switches on large consumers when the system delivers a surplus: boiler, heat pump, wallbox. Turns individual parts into a system.

ESTI — The Federal Inspectorate for Heavy Current Installations: the supervisory authority for electrical installations. For you mainly relevant as the authority behind the safety regulations according to which specialist companies work.

H

Guarantee of origin (GO) — The certificate that certifies the ecological origin of your solar power. It can be sold separately from the electricity – some utilities remunerate it additionally: Sell GO.

Hybrid inverter — An inverter with built-in battery connection. Makes the system «battery-ready»: the battery can dock later without a second device becoming necessary.

I

In-roof system — The modules replace the roof covering instead of being mounted on it (on-roof). Optically flush, structurally more demanding – sensible above all if the roof is being re-covered anyway: In-roof photovoltaics.

J

Seasonal performance factor (SPF) — The efficiency measure of the heat pump: the ratio of generated heat to used power, measured over the entire year. What makes a good SPF: Understand SPF.

K

Kilowatt (kW) — The unit of power – i.e. what a device or system generates or consumes in a moment.

Kilowatt hour (kWh) — The unit of energy: one kilowatt for one hour. In kWh your consumption, your production and every electricity bill are measured.

Kilowatt peak (kWp) — The standardised peak performance of a solar system under test conditions – the comparison value for system size and price. Why «peak» and what the number practically means: Watt peak explained.

L

Load management — The control that distributes available electrical power to multiple consumers – so that heat pump, wallbox and stove do not draw the maximum at the same time and the house connection is sufficient.

LEG (local electricity community) — Possible since 2026: neighbours share solar power via the public grid, within a defined perimeter. How this works: Local electricity community.

Power optimiser — Small electronics on the individual module that limit shading losses. Not a standard component, but a targeted tool for difficult roofs: Power optimiser.

M

Notification procedure — The simplified procedure for solar systems on suitable roofs: the system is reported to the municipality instead of being approved via building application. Details and exceptions: Permit and notification procedure.

Microinverter — One small inverter per module instead of a central device. When this is sensible – and when not: Microinverter.

Monitoring — The monitoring of the system via app or portal: production, self-consumption, fault reports. The most important operating tool of all: Use monitoring properly.

monocrystalline / polycrystalline — The two classic cell types of solar modules; today monocrystalline dominates. The difference and why it is rarely decisive for a purchase: Cell types in comparison.

N

Grid connection request — The request to the grid operator with which the solar system is registered for connection to the power grid – before installation, so that power, meter space and possible grid reinforcements are clarified. As a rule, the installer submits it. Process: Grid connection request for the solar system.

Grid operator — The company that operates the power grid at your location – in practice usually identical to your utility (see Utility).

Grid usage — The fee for the transport of electricity through the grid; an essential part of your purchase tariff. For self-consumed solar power it does not apply – a core piece of its value.

Backup power — The continued supply of the house in the event of a grid failure. No battery can do that «just like that»: it requires an expressly built system with its own wiring for it: Backup power with battery.

usable capacity — The part of the storage capacity that can actually be drawn. The honest basis for comparison when buying a battery – prices should be compared per usable kilowatt hour: Battery storage costs.

P

Photovoltaics (PV) — The generation of electricity from light – the basic principle of every solar system. Explained without jargon in Chapter 1 of the solar guide, technically deepened in the Technology guide.

Pronovo — The processing agency of the federal government for the one-off feed-in incentive and the guarantees of origin. Here your system is registered and the incentive is paid out: Pronovo registration step by step.

R

Reference market price — The market value of solar power published quarterly by the federal government. Many utilities couple their feed-in tariff to it – therefore the remuneration there fluctuates from quarter to quarter: Reference market price explained.

Feed-in — The surplus power that your system feeds into the public grid. The counterpart to self-consumption; also called «feed-in».

Feed-in tariff — What your utility remunerates per fed-in kilowatt hour. Model and amount differ significantly depending on the utility – the comparison for the region: Feed-in tariffs at a glance.

S

turnkey — A quote that includes everything: material, installation, electrical work, scaffolding, registrations. The only clean basis for comparison between quotes – missing items quickly make «cheap» expensive.

safety certificate (SiNa) — The proof that an electrical installation complies with regulations. Must absolutely be kept in your records after installation – reputable specialist companies provide it unsolicited.

Smart meter — The intelligent electricity meter: it measures precisely to the quarter-hour and in both directions. The data basis for billing and control: Smart meters in Switzerland.

Solar module — The component on the roof that converts light into direct current – colloquially the «panel». Several modules together form the system.

Solar obligation — The legal obligation to use solar energy for certain buildings – the federal government for large roofs, cantons partly for new builds. Who it affects: Solar obligation Switzerland.

Solar professional — The label of the industry association Swissolar for companies that meet requirements for qualification and further training. A voluntary additional signal when choosing a company – no substitute for references and a complete quote. What it means and what it does not: Swissolar professionals and labels.

Solar thermal — Solar collectors that generate heat instead of electricity – for hot water or heating support. Not the same as photovoltaics; the two mostly compete for the same roof space today, and PV wins the comparison more often.

sonnendach.ch — The official federal portal that shows the solar suitability of practically every Swiss roof – free of charge, exact to the address. How to read it: Using sonnendach.ch correctly.

Blocking times — Time windows in which the utility may briefly interrupt controllable consumers like heat pumps or boilers – usually in exchange for a cheaper tariff: Heat pump and electricity tariff.

String — A series of modules connected in series that hang together on the inverter. Relevant for shading: what affects one string affects all its modules.

U

Surplus charging — The wallbox charges the e-car only with the electricity that the system provides beyond household consumption – and throttles down when a cloud passes. How this works in everyday life: Charging an e-car with solar power.

V

Shading — Shadows cast by trees, chimneys or neighbouring buildings onto the modules – the most important single yield factor in planning: Understanding shading.

Full feed-in — The model in which the entire production flows into the grid instead of your own home. The exception in Switzerland; for most single-family homes, self-consumption is more economical.

Full cycle — A complete charge and discharge of the battery. The unit of measurement for battery ageing: Lifespan of battery storage systems.

virtual ZEV (vZEV) — The variant of the self-consumption community where measurement runs via the grid operator's meters instead of proprietary measuring technology. The comparison of the models: ZEV, vZEV or LEG?.

W

Wallbox — The permanently installed charging station for the e-car. For solar charging, one thing counts above all: that it can be controlled (see surplus charging).

Heat pump — The heating system that uses electricity to make environmental heat usable – and the largest single electricity consumer in the house. Why it and the solar system belong together: Heat pump and photovoltaics.

Inverter — The device that translates the direct current from the modules into alternating current for your sockets – and also monitors the entire system: The inverter.

Efficiency — The proportion of incident light that a module converts into electricity. Important, but overestimated – why a few percentage points are rarely decisive for a purchase: Efficiency of solar modules.

Z

Bidirectional meter — The electricity meter that measures consumption and feed-in separately – the basis of your billing. Who measures what, from the utility meter to the app: Meters and measurement.

Self-consumption community (ZEV) — Multiple parties – for instance in an apartment building – share the solar power behind a common grid connection. Models, rules and alternatives: ZEV, vZEV or LEG?.

### Keep in mind Those who understand the quote, tariff sheet and consultation make better decisions: The three terms on which almost everything depends are kWp (size), self-consumption rate (profitability) and feed-in tariff (surplus).

In brief

What is the difference between kW, kWh and kWp? kW measures power (what is currently flowing), kWh measures energy (what accumulates over time), kWp the standardised peak power of a solar system. Memory aid: The system is bought in kWp, produces kWh – and your appliances draw kW.

What is the difference between photovoltaics and solar thermal? Photovoltaics turns light into electricity, solar thermal turns light into heat. When people talk about a «solar system» today, they almost always mean photovoltaics – electricity can be used more versatilely, including for heating via a heat pump.

Self-consumption rate or degree of self-sufficiency – which number counts? Both describe your house, but from opposite directions: The rate measures the self-used share of production, the degree of self-sufficiency the solar-covered share of consumption. For money, the rate primarily counts – it decides how much electricity you do not have to feed in cheaply.

A term is missing – or a quote raises questions? Call us without obligation: We are an installation company from the region and are happy to translate the small print into understandable English as well. +41 78 830 83 35

Solar guide: To the guide overview · Chapter 1: How solar energy works · The 12 biggest solar myths

Sources: Use of terms according to the Swiss Federal Office of Energy SFOE, ElCom, Pronovo and Swissolar; definitions consistent with the linked guide articles.

Last updated: 9 July 2026 · Author: ecoEn editorial team