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What a behind-the-meter battery does for a business

A behind-the-meter battery sits on the site's side of the grid meter. The grid operator and the supplier never bill the battery itself: they bill the meter's 15-minute values, and the battery changes those values by charging at some moments and discharging at others. That can lower the peak, keep the site's own solar instead of exporting it, move energy to cheaper hours, or keep the site under a connection limit. It produces no energy and loses some on every cycle, so it only pays where the tariff or the connection rewards a different meter profile.

6 min read · Updated 2026-10-30

Where it sits

Behind the meter means inside the site's own installation: the loads and any solar panels on one side, the grid meter on the other, and the battery wired in between. Everything the battery does reaches the bill only through what the meter records.

  • A C&I battery is usually one cabinet or a few: battery modules, a battery inverter (often called the PCS, power conversion system) and a controller. The sonnenPro Compact 261 is one outdoor cabinet with 245 kWh usable and a built-in 125 kW inverter (sonnen datasheet); the SMA Storage XL package pairs a 197 kWh cabinet with a separate 50 kW inverter (SMA datasheet).
  • SolarPower Europe counts commercial and industrial (C&I) storage as systems of 20 kWh to 1,000 kWh; above 1 MWh it counts as utility-scale, behind or in front of the meter (SolarPower Europe, June 2026). National statistics use other size bands, so figures from different sources are not directly comparable.

What the meter sees

The bill is calculated from the meter's interval values. In the Netherlands the monthly kWmax is the highest load per clock quarter-hour (Stedin); in Germany the Leistungspreis is set by the year's highest 15-minute load (NEW Netz 2026). A battery's only lever is to change those values.

Illustrative: in one quarter-hour the site draws 400 kW. If the battery discharges 60 kW in that quarter-hour, the meter records 400 − 60 = 340 kW. If it recharges at 60 kW in a quiet hour when the site draws 150 kW, the meter records 150 + 60 = 210 kW then. The energy has moved in time; the site has not used less.

What decides when it charges and discharges

An energy management system (EMS) controls the battery by rules: keep the import under a threshold, store surplus solar, charge when power is cheap. The open-source OpenEMS, for example, has separate controllers for peak shaving, time-slot peak shaving and time-of-use tariffs (OpenEMS repository).

The EMS does not know tomorrow's load. That is why a study should take its expected savings from a rule-based simulation and use an optimiser that knows the whole year only as the upper bound. See Rule-based vs optimal dispatch.

The four jobs it can do

  • Cut the peak: discharge when the load is highest, so the charge per kW falls.
  • Keep the site's own solar: store the midday surplus and use it in the evening instead of exporting it.
  • Move energy in time: on a dynamic contract, charge in cheap hours and discharge in expensive ones.
  • Hold a connection limit: let the site add load without a bigger grid connection.

Which job carries the case depends on the tariff and the site; The four ways a business battery earns goes through each one with its bill line.

Why businesses are adding them

  • In Europe, C&I battery installations grew from 2.2 GWh in 2024 to 4.7 GWh in 2025 (+77%), with 5.9 GWh forecast for 2026 (SolarPower Europe 2025, SolarPower Europe 2026).
  • Most C&I solar has no battery yet. SolarPower Europe puts the ratio of C&I solar to C&I storage at 30:1 at the end of 2025, and the attachment rate (the share of C&I solar installed with a battery) at about 20% for commercial and 10% for industrial sites in 2026, after years below 5–10% (SolarPower Europe 2026).
  • The main uses the same report names are raising solar self-consumption and cutting peak demand charges, with grid-connection limits and electrification on top.

What it does not do

  • It does not produce energy or lower consumption, and every cycle loses some. One datasheet quotes a battery-only efficiency of up to 98% (SMA); a 2022 assessment by the US Pacific Northwest National Laboratory uses 86.00% for a lithium iron phosphate (LFP) system measured AC to AC at the inverter (PNNL 2022).
  • It uses power for its own cooling and control, even when idle. In a field test of a 1 MWh utility-scale system the auxiliary load was 30 kW (PNNL, MESA-1 test report). No published figure for C&I cabinets was found; ask the vendor.
  • It is not automatically a backup supply. Running a site through a grid outage needs a product and an installation designed for it; sonnen, for example, lists a separate backup box for its C&I cabinet (sonnen datasheet). A feasibility study does not design backup or electrical protection.

To see what a peak cut could be worth, try the free peak-shaving calculator. The Workspace runs a year of the site's 15-minute data through its real tariff; your first site analysis is free.

Frequently asked questions

Is a C&I battery just a big home battery?
It is usually larger and three-phase, often with the inverter in the same cabinet, and it is judged on the site's 15-minute peaks, tariff and connection rather than on one household's self-consumption. SolarPower Europe's C&I band is 20 kWh to 1,000 kWh.
Do I need solar panels for a battery to pay?
No. Peak shaving, the connection limit and arbitrage work without solar. Solar adds a value stream when the site exports at midday and imports later.
Will it keep the site running in a power cut?
Only if the product and the installation are designed for backup, which many grid-tied systems are not. Ask the installer; a feasibility study does not cover it.
How long does a C&I battery last?
29 of the 44 products in Zorowatt's battery database state a 10-year warranty, usually with a limit on cycles or energy throughput and an end-of-life capacity of 60–70%. The guide on degradation and warranties shows how to turn those terms into a study assumption.

Related guides

Sources

Last checked: 2026-10-30. Every figure in this guide comes from the source linked next to it, with the retrieval date Zorowatt's research recorded (28–30 October 2026), or from arithmetic shown step by step.

Stuck on something else? Ask the community.

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