Grid-scale storage — standalone or beside a generation plant.

Land is rarely the bottleneck. A 20 MW system fits on around half a hectare; projects are feasible from roughly 0.3 ha, and 0.5 to 2 ha is typical. What decides it is the distance to the grid connection point and the capacity available there — a large site without the grid is worthless, a small one at the right point is not. The suitability criteria in detail are on the page for landowners.

Two items that are often confused. The connection itself — cable, transformer station, switchgear bay, wayleaves — rises with every metre of line. The construction cost contribution to the grid operator rises with connection capacity and the local capacity price; because that price is set per grid area, the same system can differ several-fold between two sites. A ballpark figure on a website would therefore mislead: the number comes out of the grid pre-check, and for us that stands at the beginning, not the end.

A one-off contribution by the connecting party to the costs of the upstream grid; above low voltage the grid operator calculates it under the capacity price model. The operator of the storage system pays it. That this also applies to battery storage was confirmed by the Federal Court of Justice on 15 July 2025 — even though storage does not consume the electricity it takes, but feeds it back later.¹² Because it steers site selection, we estimate it before securing land rather than after; the details are in Regulation.

From a complete request to an offer we reckon with 3 to 18 months, and from the offer to readiness to build with another 6 to 18. The range is not evasion — it depends on the grid operator, the voltage level and whether a grid compatibility study or network reinforcement is needed. What can be influenced is the completeness of the request: missing documents cost more time than any technical query. Under the grid connection package, from 2027 it is meant to be demonstrable maturity that counts rather than order of arrival.¹¹

The application rule covers every customer installation on the 1 to 60 kV medium-voltage grid, storage included, and sets out a three-step chain of evidence: unit certificates for the components, a plant certificate for the design, a declaration of conformity after construction. Without a plant certificate there is no commissioning.¹³ The practical point is timing: requirements for reactive power, protection settings and grid behaviour drive the design — whoever brings in the certifier only after detailed engineering plans twice.

Market-driven means the system follows price: charging when electricity is cheap, discharging when it is expensive. Grid-serving means it follows the situation in the network, absorbing generation that would otherwise be curtailed and relieving congestion. In practice this is not either/or but a priority in the schedule and a question of the contract with the grid operator. It still has to be settled, and settled in advance — otherwise chance decides when the two conflict.

Storage and generation share one grid connection point. That removes the most expensive and slowest single item of a project, the new connection. It almost always pays where a connection exists and is not fully used — with photovoltaics in particular, because generation and price profiles run in opposite directions. The catch lies in the metering separation while the existing plant still receives a feed-in tariff; that is governed by the MiSpeL determination, scheduled to enter into force on 1 October 2026.¹⁰

As a rule, yes. In the outer area the privilege under section 35 BauGB has, since December 2025, been able to spare a development plan procedure: in spatial and functional connection with an existing renewable installation, or from 4 MW within 200 metres of a substation.¹⁴ That does not replace the building permit itself — noise, fire safety and species protection reports are part of it. And the privilege is capped per municipality, which makes it a scarce good: whoever applies first uses up an allowance the next applicant will lack.

Design life is taken as 15 to 20 operating years, while leases usually run 20 to 25 — the difference is deliberate and covers replacement and decommissioning. Cells age by two mechanisms at once: by cycle and by time. Manufacturers therefore guarantee a residual capacity at a given date, but only under conditions written into the contract: temperature window, C-rate, cycles per year. Leaving those conditions in operation does not cost you the plant, but it costs you the basis of its calculation.

Two things that belong apart. Decommissioning is part of the contract and backed by security, so that it does not fall to the landowner; the site is returned in the condition in which it was taken. What happens to the cells — second life in less demanding applications, or material recovery — will be decided by a market that does not yet exist at this scale. That is the honest state of it, and we say no more than that.

If the connection allows, yes. At a wind farm, storage smooths forecast errors and steadies the feed-in. Because wind blows less regularly than the sun shines, it needs more capacity for the same effect than at a solar park.

It decouples the operating mode from marketing: the plant can run heat-led while the storage takes over optimisation on the power market. Whether it pays depends on connection, remuneration and heat concept — we calculate it for your plant.

It remains a grid connection point with capacity — and that is scarce. Storage can keep using it; in planning terms this is often simpler because the land is already in use.