What happens after 6 years, when the BESS agreement ends?

When a company enters an availability and optimisation agreement for an industrial battery energy storage system (BESS), the agreement typically runs for 6 years. One of the questions a CFO or owner-manager rightly asks early on is therefore: what happens when those 6 years are over? Do we still own the plant? Can we decide what happens next? And is the battery worth anything afterwards?

This article explains what changes, and what does not change, when the agreement period ends. In short: our exclusive right to optimise the plant commercially ends automatically, but the asset remains the customer's, and the customer is free to choose what happens next. The article also describes what value after year 6 realistically depends on. We keep the tone measured on purpose, because no one can guarantee the market of the future.

The optimisation right ends automatically

During the agreement period, we hold the exclusive right to optimise the plant's flexibility commercially. That is the right the customer receives a fixed contractual availability payment for making available. When the 6 years are over, that right ends automatically, unless we and the customer enter a new agreement.

Nothing needs to be terminated, and there is no automatic extension. At the end of the agreement period, our exclusive right to use the battery's flexibility commercially falls away, and the customer is free to decide. If both parties wish to continue, that requires a new, active agreement. If the customer wants something else, nothing binds the customer to us after expiry.

It is a deliberately simple construction. The customer should not be in doubt that the collaboration has a clear end date, and that continuation is a choice, not a default state.

The customer still owns the plant

The most important point to keep in mind is that ownership of the physical plant is not tied to the optimisation right. The customer has purchased and owns the physical BESS plant under the agreed payment and transfer terms, and that ownership is not affected when our optimisation right ends.

When the agreement ends, the customer is therefore left with a plant the business itself owns. What changes is not ownership, but who is allowed to use the plant's flexibility commercially. During the agreement period, that was us. After expiry, it is up to the customer.

One thing does not transfer, however: the software, the algorithms, the trading strategies, and the optimisation models we use to operate the plant in the market are not transferred to the customer. They remain with us and our partners. The customer owns the hardware, not the commercial control logic. That matters for the choices after year 6, which we turn to now.

The customer's options after expiry

Because the customer owns the plant and is free to decide, there are in practice several paths after the 6 years. The main ones are:

• Continue with ZynexGroup: The customer can enter a new agreement with us on the terms agreed at that time.
• Choose another aggregator: The customer can let another party handle the commercial optimisation.
• Choose a new BRP or trading partner: The customer can change the party that handles trading and balance responsibility in the market.
• Use the plant more for own optimisation: The customer can use the battery for its own purposes, for example own-consumption optimisation, to the extent that is technically possible.

To understand the middle two options, it helps to know two concepts. An aggregator is a party that pools and controls flexibility from one or more plants and bids it into the electricity markets on the owner's behalf. A balance responsible party, often abbreviated BRP, is the party that is financially responsible for keeping balance between what is agreed and what is actually delivered in the electricity system.

That the customer can in practice choose another party is not merely something we claim. It follows from the European electricity market rules. Customers have the right to switch supplier or the party that exercises aggregation, and from 2026 the technical switch itself must be possible within 24 hours on a working day. The same rules establish that parties that exercise aggregation, including independent aggregators, can enter the electricity markets without the consent of other market participants, and that they must be balance responsible or delegate balance responsibility. The right to choose another operator is, in other words, built into the market design.

What we cannot promise is that a particular choice delivers a particular financial outcome. Whether it is most advantageous to continue with us, switch to another operator, or use the plant more for its own purposes depends on the concrete terms and market conditions at that time. The choice is the customer's, and it should be made on a concrete basis, not on a promise.

What value after year 6 depends on

The battery is not used up after 6 years, but we also cannot put a general figure in kroner on what it is worth afterwards. Value after the agreement period depends on several things that can only be assessed concretely at that time.

The plant's technical condition: The technical lifetime of lithium batteries for stationary storage typically extends well beyond 6 years. Where laboratory tests often run for 1 to 2 years, stationary storage plants are in practice assessed over operating horizons of 10 to 20 years or more. But the actual condition, measured as State of Health (SoH), that is, how much of the original capacity remains, depends on how the plant has been used. For large LFP cells for stationary storage, temperature is a dominant degradation factor, and capacity loss can roughly double when temperature rises from 35 to 50 degrees. Our model operates within technical and warranty frameworks with an SoH threshold of 80% at the end of the agreement period and cycle use within the agreement's and the manufacturer's frameworks (up to 6,000 full equivalent cycles). The actual residual capacity depends on the documented SoH and operating history.

Market access: A battery only creates value in the market when it has access to deliver. A plant must be prequalified with Energinet, Denmark's national transmission system operator, before it may deliver system services, and prequalified plants must be reassessed at least every five years. There are also special technical requirements for plants with limited energy reservoir, which batteries fall under. Market access is therefore not automatic after year 6; it assumes that the plant continues to meet the technical requirements.

Software and service: Value also depends on whether there is a party that provides control software, market access, and ongoing monitoring. Because our control logic is not transferred, a new model will require either a new agreement with us or an agreement with another operator that can deliver that part.

Future rules: The regulatory frameworks evolve on an ongoing basis. The EU's electricity market design is under reform, among other things to strengthen short-term markets and secure long-term price signals. That can change both the opportunities and the requirements over a 6-year period, in both directions.

The market after year 6 cannot be guaranteed

It is tempting to present the time after the agreement period as a secure gain, where the customer can now harvest the market revenues itself. That would not be fair. The market for flexibility can develop, but no one can guarantee what it looks like in 6 years.

There are factors that point toward continued need. Energinet expects the total need for system services to rise significantly toward 2040, on the order of 150%, primarily driven by more wind and solar. Energinet itself stresses, however, that these are best estimates in a future with substantial uncertainty. At the same time, more parties have entered the market: Energinet's connection cases involving batteries grew from around 400 MW at the end of 2023 to around 6,200 MW in mid-2025. More parties argue that there will also be aggregators and trading partners to choose among going forward.

But the same development has another side. When earnings from frequency regulation in eastern Denmark (the DK2 price area) were attractive early on, that market quickly became more or less saturated, and the industry points out that revenues from system services and balancing cannot stand alone. That is why the larger markets are used as well. In addition to system services there are the day-ahead market (the spot market), the intraday market, and the balancing market, and the transition to common European platforms has opened more of the markets to more participants. Part of the value can also lie in arbitrage, that is, charging in hours with low prices and discharging in hours with high prices.

The realistic picture is therefore twofold. There are good reasons to expect a continued need for flexibility, and there will likely be several ways to use the plant. But individual markets can saturate, prices can move, and there is no certainty of a particular level of earnings. That is precisely why a decision about what should happen after year 6 should be made on the basis of conditions at that time, and not on the basis of a promise made in advance.

Limitations and assumptions

This article describes the general model, not a concrete commitment about what a particular plant will be worth, or what it will be able to earn after year 6. We deliberately state no residual value in kroner, because it cannot be set generally today. It depends on the plant's actual SoH, future market conditions, technical requirements, and on what the customer chooses.

The battery lifetime research we refer to is general and describes mechanisms and typical horizons, not the condition of a particular plant. The market projections we mention are estimates from Energinet, not guarantees. And the switching right in the European rules covers the right to choose and switch operator; it says nothing about what concrete terms a future agreement with us or another party will contain. In short: the options are real, but they must be assessed concretely when the time approaches.

ZynexGroup's approach to plant assessment

When we enter an agreement, it is with the understanding that the customer owns a physical asset that still has technical value after the agreement period. That is why SoH, cycle limits, and manufacturer warranties are central elements in the agreement, and we operate the plant within the technical and warranty frameworks throughout the period.

We would like to continue the collaboration after the 6 years, and we will offer the customer a new agreement. But we do not promise specific future terms, amounts, or market conditions in advance, because that would not be a serious approach. Our role up to expiry is to give the customer a concrete, data-based basis on which to make its choice, whether that choice is to continue with us, switch to another operator, or use the plant more for its own purposes.

We offer an actual 6-year payback guarantee on BESS plants. It is tied to the payment model in the agreement period and does not change the fact that what happens after year 6 is the customer's choice on a basis that can only be finally assessed at that time.

Overall perspective

After the first 6 years, our exclusive optimisation right ends automatically, unless the parties enter a new agreement. The asset remains the customer's, and the customer can choose to continue with us, choose another aggregator, choose a new BRP or trading partner, or use the plant more for own optimisation. The right to choose freely is built into the European electricity market rules.

Value after year 6, by contrast, cannot be guaranteed. It depends on the plant's actual SoH, on market access and technical requirements, on software and service, and on future rules. The need for flexibility is expected to grow, but that is an expectation, not a certainty, and individual markets can saturate. The picture that remains is simple and honest: the customer owns a plant with continued technical value and has the freedom to choose the next model itself when the 6 years are over.

Have the potential for your facility assessed

If you want to understand how a 6-year agreement and the time after it look for your specific plant, we can have a data-based conversation. We typically look at your grid connection, your consumption profile, and your historical consumption data to make an initial assessment of whether there is a match, and how the agreement period and the choices afterwards may look in your case.

You are welcome to contact us for an initial, no-obligation conversation.