Commercial battery storage: what drives the price and the payback

28 October 2026 · 6 min read

The battery price is only part of the total and payback does not come from a price list but from your load profile. What drives the cost of commercial storage and when it pays off – and when not yet.

Why the price of storage cannot be read from a price list

Battery storage for a business is not an appliance you buy and plug in. It is a generating installation under the Energy Act, a building under the Building Act and equipment connected to the distribution grid under the grid operator's conditions. The price of the batteries themselves is only part of the whole – and often not the decisive one. Likewise, payback does not come from a single number but from how and when the business consumes electricity and what it pays for it and for its connection. That is why a study comes first, and the size and technology are chosen from it.

What makes up the cost of building storage

Item	What drives it
Batteries and power electronics	Capacity in kWh and power in kW, the power-to-capacity ratio (one-hour or two-hour storage), cell chemistry, cooling, the container's fire protection system, warranty and cycle life.
Grid connection	At low voltage a switchboard and a cable to the existing site switchboard are enough; from hundreds of kW the grid operator usually requires a medium-voltage connection – and therefore a transformer station, an MV feeder and MV switchgear. Next to the batteries this is often the largest item.
Civil works	Foundations for the containers and the transformer station, paved areas, fencing, cable routes, drainage and, where needed, noise measures and clearances under the fire safety solution.
Metering and control	Commercial metering, sub-metering of generation where storage shares a connection with PV, the energy management system (EMS), communication with the grid operator and an aggregator, the disconnection point and grid protection under the operator's conditions.
Design, permit and connection	Study, connection application, permit documentation, detailed design, statements from utility owners and concerned authorities, permitting services, as-built documentation. Details in the article on permit documentation for battery storage.
Operation	Service, insurance, capacity degradation, grid charges for the reserved capacity used to charge from the grid and, where applicable, the aggregator's fees.

The larger the storage, the smaller the share of the technology in the total and the more the connection and civil works matter. Storage added to an existing PV plant or transformer station, on the other hand, uses what is already on site.

What makes up the payback

Storage earns by shifting electricity in time. For a business it is usually a combination of several sources of savings; which one prevails depends on the load profile and the contracts:

Peak shaving – businesses at medium voltage pay the grid operator for the contracted capacity (reserved capacity or power) and for exceeding it. Storage covers short peaks and allows a lower reservation to be contracted. The saving is calculated from the 15-minute load profile for a whole year, not from an estimate.
Self-consumption from PV – surpluses from the plant that would go to the grid at a low feed-in price are stored for the evening and night. It pays where generation and consumption are out of step in time.
Price differences during the day – charging in cheap hours and discharging in expensive ones, if the business buys electricity at spot-linked or two-tariff prices.
Ancillary services and flexibility – for larger storage, power can be offered through an aggregator for balancing services. As batteries have multiplied in Czechia, the prices of these services have fallen sharply over the last two years and keep falling; today they are a supplement, not a reason to build storage. The study treats them conservatively, or leaves them out.
Backup – storage can cover a grid outage for selected circuits; it is not a revenue, but the backup generator becomes smaller or unnecessary.

Added to this are the reliefs from regulated charges for electricity storage: since August 2026, electricity drawn from the grid and returned to it is, under set conditions, exempt from part of the regulated charges. The conditions include a connection contract that permits storage at the point of delivery, interval metering, registration in the EDC data centre and, for storage sharing a connection with PV, separate metering of generation. The conditions and the amount of the reliefs evolve with the tariff structure, so the study takes them from the current price decision and the contract with the grid operator – and we design the metering for them into the project from the start, since it is hard to add later.

Against the revenues stand charging and discharging losses, battery degradation and operating costs. A good study counts all three and shows whether the full system pays off, a smaller variant – or nothing for now. Sometimes it turns out that the biggest saving comes simply from a better contracted capacity without a battery; that too is a result worth knowing before investing.

What decides the size of the storage

Load profile – how large and how frequent the peaks are and how long they last; 15-minute data from the grid operator or your own metering for a whole year.
Purpose – peak shaving needs a different power-to-capacity ratio than storing PV surpluses or providing grid services.
Connection – the grid operator's statement on the connection application sets how much power can be fed in and drawn and at which voltage level; more in the article on how to connect battery storage to the grid.
Site – space for the containers and the transformer station, clearances from buildings and boundaries, noise towards neighbouring housing, access for transport and fire services.
Expansion – whether the storage should be ready for another container or for future PV.

How we proceed

Site and document check – the plot, zoning plan, protection zones, nearest lines and transformer stations, the existing connection contract and invoices.
Study – from the 15-minute load profile and the prices in your contracts we calculate the saving for several storage sizes, propose the layout and connection and compare the variants, including “no battery”.
Connection application – we submit it as early as possible; only the grid operator's statement confirms the power and the conditions.
Documentation – for the permit and for construction, including the transformer station, foundations, lightning protection and the fire safety solution; tendering of the technology from the bill of quantities.
Construction and commissioning – designer's supervision, as-built documentation, documents for the grid operator and for the first parallel connection.

The whole service is described on the battery storage design page.

Frequently asked questions

Does battery storage pay off for every business?

No. It pays where there are pronounced short peaks in demand, where PV generation and consumption are out of step, or where the business buys electricity at market-linked prices. A study from your data shows this before you decide; the result “do not buy yet” is as valid as a recommendation to invest.

How long until the storage is standing?

The delivery and installation of the containers themselves take weeks. The overall time, however, is set by the grid operator's connection statement and the building permit – for storage with its own transformer station usually a year or more. That is why we submit the connection application right at the start.

Does storage need a building permit?

Containerised storage with a transformer station is a building and needs a permit; the documentation has a fixed structure under Czech Decree No. 131/2024 Coll. Small storage inside an existing building may be only a change to the electrical installation – we assess this at the start.

Can storage be added to an existing PV plant?

Yes, it is a common case. What matters is the existing connection contract (the plant's power), the space at the switchboard or transformer station and whether you want to store surpluses or also shave peaks. With a shared connection with the plant, generation metering is handled separately.

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