Glossary: energy terms for industry and commerce

Ancillary services (SDL): Systemdienstleistungen (ancillary services, SDL) are the services Swissgrid buys as transmission system operator to run the Swiss electricity grid securely: control reserve in three tiers (primary, secondary and tertiary), voltage support, black-start capability and the provision of imbalance energy. The costs are passed on to end consumers through the SDL tariff. For battery storage operators, SDL is the umbrella term for revenue from the balancing energy market, which site studies examine as a third revenue lever alongside peak shaving and self-consumption optimisation.
Balance group: A Bilanzgruppe (balance group) is a grouping of feed-in and offtake points in the Swiss electricity grid for which a balance group manager, usually a utility or an energy trader, registers schedules with Swissgrid. The manager procures the energy in advance in hourly blocks based on its own forecasts. Where real consumption or PV production deviates from that, imbalance energy arises, which Swissgrid invoices to the balance group. As the PV share grows, forecast errors increase and with them the need for balancing energy.
Balancing energy: Regelenergie (balancing energy) is the energy Swissgrid, as transmission system operator, calls up at short notice to keep generation and consumption in the Swiss electricity grid in balance at all times. It is provided in three tiers: primary control reserve within 30 seconds, secondary control reserve within 5 minutes and tertiary control reserve for imbalances lasting more than 15 minutes. In 2025, Switzerland activated around 1'160 GWh of balancing energy, against around 700 GWh in 2020 (ElCom). Providers are paid for capacity held and energy activated.
Billing service provider: A billing service provider (Abrechnungsdienstleister) handles meter data processing and invoicing for the shared solar electricity in a ZEV, vZEV or LEG and, depending on the model, for grid electricity as well. In a ZEV and vZEV it bills both to the participants; in a LEG only the community electricity, while the grid operator bills residual electricity and grid usage. The role can be taken by a specialised company, the grid operator itself or the system operator.
Demand charge: The Leistungspreis is the demand charge on Swiss electricity bills: the component commercial and industrial businesses pay for their maximum power draw, billed in CHF per kilowatt. For most Swiss distribution grid operators, the highest 15-minute average of the month is decisive. A single short load peak can therefore determine the grid costs of the entire month, regardless of actual energy consumption.
Dynamic tariff: A dynamic tariff is an electricity tariff whose price changes over the day with the exchange price and the expected grid load, instead of being fixed in high and low tariff periods. EKZ has sent price signals at 15-minute intervals since 1 January 2026 in a band of plus/minus 5 Rp./kWh around the standard tariff; CKW varies its grid tariff between 0.1 and 32 Rp./kWh. Businesses with storage, charging stations and an energy management system shift their consumption into the hours with low prices.
Energy management system: An energy management system (EMS) is the control centre of a commercial energy installation: it monitors production, consumption and storage level in real time and coordinates the PV system, battery storage, flexible loads and charging infrastructure against economic targets. Typical functions are peak shaving, self-consumption optimisation and prioritised charging. Modern systems use load forecasts and machine learning to anticipate recurring patterns.
Grid level: The Netzebene (grid level) denotes one of the seven tiers into which the Swiss electricity grid is divided, from the extra-high voltage of the transmission grid (grid level 1) to low voltage at the end consumer (grid level 7). The odd levels 1, 3, 5 and 7 are voltage levels; the even levels 2, 4 and 6 are the transformation stages between them. The grid level matters for self-consumption models because a LEG may only use levels up to 36 kV, in practice levels 5 and 7.
Grid operator practice model (VNB-Praxismodell): The VNB-Praxismodell (grid operator practice model) is an industry practice, widespread since 2014, in which the distribution grid operator (VNB) distributes a property's solar electricity to the tenants through its own meters and bills it. The tenants remain end customers of the grid operator; the system operator receives a credit for the solar electricity delivered. Unlike ZEV, vZEV and LEG, the model is not set out in any law; it rests on a contract between system operator and grid operator.
Grid usage charge: The Netzentgelt (grid usage charge) is the part of the electricity bill the distribution grid operator charges for use of the grid, independent of the energy supplier. It consists of consumption-based components in Rp./kWh and the demand charge in CHF/kW on the monthly peak. Solar electricity from your own roof never passes through the public grid and therefore avoids the grid charge entirely.
Hail resistance class (HW3/HW4): The Hagelschutzklasse (hail resistance class, HW) states which hailstone a component of the building envelope withstands without damage; the number corresponds to the hailstone diameter in centimetres, so HW3 means 3 cm and HW4 means 4 cm. For solar modules, SIA 261/1 and the VKF hail register treat HW3 as the baseline; in designated hail regions, Swissolar fact sheet 17 recommends HW4. No cantonal legal requirement exists for PV modules.
Imbalance energy (Ausgleichsenergie): Ausgleichsenergie (imbalance energy) is the difference between a balance group's registered schedule and its actual consumption or actual feed-in in each settlement interval. Swissgrid covers this deviation with balancing energy and invoices it to the balance group manager at an imbalance price that follows the cost of the balancing energy activated. The fluctuating PV production of prosumers is one of the main causes of forecast errors; in 2024 it drove up the activation prices for secondary balancing energy (Swissgrid Balancing Roadmap).
LEG: A LEG (Lokale Elektrizitätsgemeinschaft, local electricity community) has allowed the trading of locally produced electricity across the public grid within a neighbourhood or municipality since 1 January 2026. For community electricity, participants pay a grid usage charge reduced by 40 percent, or by 20 percent where the electricity passes through a voltage transformation. Unlike a ZEV or vZEV, participants may use different grid connection points within the same grid area; smart meters are mandatory.
Load profile: The Lastgang is the Swiss term for a site's time-resolved load profile, measured by default in 15-minute average values. It shows when how much power is drawn: base load, production peaks, weekend and seasonal patterns. For sizing a PV system, battery storage and charging infrastructure, the load profile analysis is the central data basis, because it determines self-consumption potential, storage size and the savings potential on the demand charge.
Merit order: The merit order is the dispatch sequence of power plants on the electricity market, ranked by marginal cost from the lowest to the highest. On the power exchange, the most expensive plant that still has to be switched on to cover demand sets the price for every supplier in that hour. In many hours that plant burns gas, which is why the gas price shapes electricity prices in Europe and therefore in Switzerland as well.
One-off remuneration (EIV): The Einmalvergütung (EIV) is Switzerland's central federal subsidy for photovoltaic systems, paid as a one-off investment contribution at commissioning by the executing agency Pronovo. It comprises KLEIV for systems below 100 kWp, GREIV for systems from 100 kWp up to 50 MWp, and HEIV for full feed-in systems from 2 to 150 kWp. Since 2025, additional bonuses apply, for example for integrated systems and carport canopies.
Peak Shaving: Peak shaving is the targeted capping of load peaks in a site's electricity draw, usually with a battery storage system. The battery discharges when a load peak approaches and thereby reduces the measured maximum power draw, the basis of the demand charge. Swiss grid operators typically measure the highest 15-minute average of the month for this purpose.
Pooling: Pooling is the bundling of several systems, such as PV systems, battery storage systems or controllable loads, into one virtual unit that takes part jointly in Swissgrid's balancing energy market. The pool operator handles registration, tenders and control; each system connects through a modem. Pooling opens the market to systems that alone fall short of the minimum bid of 1 MW (primary control reserve and, from mid-2026, tertiary control reserve) or 5 MW (secondary control reserve). The basis is a pooling contract between system owner and pool operator.
Primary control reserve (PRL): Primärregelleistung (primary control reserve, PRL) is the first tier of control reserve in the Swiss electricity grid: it stabilises grid frequency automatically within 30 seconds of a disturbance, such as the outage of a power plant. Swissgrid held around 70 MW for this on annual average in 2025; from 2026 it is 80 MW (ElCom). The minimum bid is 1 MW; smaller systems take part through a pool. Battery storage systems suit this product because they change their output in both directions without start-up time.
Reference market price: The Referenzmarktpreis (reference market price) is the quarterly averaged market price for electricity calculated by the Swiss Federal Office of Energy (BFE), which has guided the statutory remuneration for fed-in solar electricity since 1 January 2026. Systems below 150 kW are additionally covered by a minimum remuneration under Art. 12 EnV. From 1 January 2027, the hourly day-ahead spot price at the time of feed-in replaces the quarterly average; the minimum remuneration is then paid as a quarterly difference payment.
Repowering: Repowering is the modernisation of an existing photovoltaic system by replacing modules, inverters or the mounting structure with current technology. Because modern modules achieve considerably higher efficiencies than systems from the 2000s and early 2010s, the yield on the same roof area rises substantially. Repowering typically pays off for ageing systems with expiring feed-in tariffs, frequent defects or sharply increased electricity demand.
Secondary control reserve (SRL): Sekundärregelleistung (secondary control reserve, SRL) is the second tier of control reserve: it relieves primary control reserve and fully balances out an imbalance in the Swiss electricity grid within 5 minutes, controlled automatically by Swissgrid. In 2025, Swissgrid held around 360 MW in both directions on annual average. Holding the reserve cost around CHF 70'000 per MW and year on average; activation as secondary balancing energy was paid at 334 EUR/MWh positive and 208 EUR/MWh negative (ElCom). The minimum bid is 5 MW until mid-2027.
Self-consumption: Eigenverbrauch is the Swiss term for self-consumption: the share of solar electricity a business uses directly on site instead of feeding it into the grid. It is the central value driver of a PV system, because self-consumed electricity replaces grid purchases at 20 to 35 Rp./kWh while feed-in earns only 5 to 12 Rp./kWh. Unoptimised systems reach 30 to 40 percent; with battery storage and a ZEV, 70 to 90 percent is achievable.
Tertiary control reserve (TRL): Tertiärregelleistung (tertiary control reserve, TRL) is the third tier of control reserve: Swissgrid activates it manually when an imbalance in the Swiss electricity grid lasts longer than 15 minutes, relieving secondary control reserve. In 2025, Swissgrid procured around 500 MW of positive and around 430 MW of negative tertiary control reserve on annual average (ElCom). From mid-2026, the minimum bid falls to 1 MW (Swissgrid Balancing Roadmap). Through a pool, PV systems without storage can also offer capacity in this market.
vZEV: The vZEV (virtueller Zusammenschluss zum Eigenverbrauch, virtual self-consumption community) has extended the ZEV model beyond the single grid connection point since 1 January 2025. It covers several plots and grid connections that are linked through the service line or the local infrastructure at the connection point below 1 kV, without using the distribution grid. Solar electricity is allocated computationally through the grid operator's smart meters. The private metering infrastructure of a classic ZEV is not needed.
Winterstrombonus: The Winterstrombonus (winter electricity bonus) is a supplementary subsidy on top of the Einmalvergütung for photovoltaic systems from 100 kWp that are commissioned from 1 January 2026 and produce more than 500 kWh per installed kilowatt during the winter half-year (1 October to 31 March). The bonus specifically supports winter-strong systems: alpine sites, steeply tilted modules and facade systems facing south-west or south-east.
ZEV: A ZEV (Zusammenschluss zum Eigenverbrauch, self-consumption community) has allowed several parties in a building or estate to share solar electricity behind a single grid connection point since 2018. All participants share the connection, and billing is consolidated. The model is relevant above all for commercial parks, industrial estates and properties with several tenants.