Energy storage (often referred to in offers as BESS, from battery energy storage system) can be a great investment - it reduces the capacity fee, allows shifting consumption between tariff zones, and makes better use of your own PV installation. The problem is that it is much harder to calculate than the PV installation itself. And it is precisely this difficulty that the weakest offers exploit.
Where do so many energy storage offers suddenly come from
The mechanism was recently described by the portal WysokieNapiecie.pl (opens in new tab) in an analysis prepared by an energy market advisor: the PV market for companies has become saturated, so some salespeople who previously sold panels are now offering storage systems - often to the same customers. Many do it professionally. But those whose only idea for a transaction is the promise of a very short payback period, wrapped in charts and difficult vocabulary, are also active.
The author of the analysis collected five cases from his advisory practice - from verifying sellers' offers to deciding whether to buy storage at all. The conclusions are instructive for anyone who has just received a "table with a 2-year payback" - which is why we summarise them below and add the perspective of an installer who sees the electrical side of such investments from the inside.
How to spot an analysis that is too good to be true
The most common sins of overly optimistic offers mentioned in the analysis are repeated regardless of the industry:
- Unrealistic battery parameters - assuming operation across the full capacity range (DoD 100%) and with zero losses (RTE efficiency 100%). A real battery storage system does not operate without losses, nor does it run "from zero to one hundred".
- No degradation and operating costs - battery capacity decreases over time, and inspections, servicing, insurance, and energy management system (EMS) fees cost money every year. Without these, the result looks beautiful only on paper.
- Relying on annual totals - the profitability of a storage system is determined in the hourly profile, day by day. One year calculated "on aggregated data" and stretched in a straight line over the entire lifetime is not a model, but a wish.
- Summing up mutually exclusive benefits - the same capacity cannot simultaneously work fully for price arbitrage (buying energy when it is cheap and using it when it is expensive), the capacity fee, and PV self-consumption. A reliable analysis shows how these revenue sources compete for power and capacity.
- Simple payback period instead of NPV and IRR - i.e., metrics that show how much the project actually earns over its entire lifetime, taking into account that a złoty in ten years is worth less than today. Without them and without scenarios (base, conservative, optimistic), it is impossible to assess the risk-to-reward ratio.
A simple rule: if the offer does not show the assumptions - DoD, efficiency, degradation, operating costs, energy price model, and power selection variants - it is not a profitability analysis, but an advertising brochure with a table.
A larger storage system does not always mean a better result
The most interesting part of the analysis concerns the sizing of the device. In one of the described cases, a plant with an annual consumption of about 18 GWh was considering a 4 MW/8 MWh storage system - so large that it required increasing the contracted capacity. Fixed costs would consequently rise by a third, and despite real energy savings, the rate of return did not satisfy the investor. After recalculating the variant with a smaller 3 MW/6 MWh storage system, without increasing the contracted capacity, the IRR turned out to be almost twice as high - with energy cost savings lower by only three percentage points (9 instead of 12 percent).
In another case, a client with an annual consumption of about 1.3 GWh was offered a 500 kW/1200 kWh storage system, which also forced an increase in the contracted capacity. The analysis showed that a 0.3 MW device would yield a rate of return about 3 percentage points higher - and under conservative assumptions, the project still had a chance to pay for itself in 3-4 years, without any sugarcoating.
Conclusion: the variant that "squeezes" the technology to the maximum does not necessarily maximize the investment value. A good analysis always compares several power and capacity options - along with all grid costs, including those that increase.
How a storage system actually makes money in a Polish company
The same analysis shows that the sources of benefits are distributed very differently depending on the plant's profile:
- Capacity fee - shifting consumption outside peak hours lowers the multiplier according to which the operator calculates this fee, and is often the main source of savings. In the described chemical plant, a relatively small 200 kW/400 kWh storage system yielded a double-digit rate of return primarily due to the capacity fee and the reduction of contracted capacity - even without price arbitrage.
- Contracted capacity - smoothing out consumption peaks sometimes allows for its reduction, which brings savings every month. It also works the other way around: a storage system selected "on the larger side" can force its increase.
- Tariff zones and price profile - charging when energy is cheap and discharging at peak times, however, requires an energy purchase model that enables this. Companies bound by a multi-year contract with a fixed price will not benefit from arbitrage without changing the contract - and this must be checked before purchase, not after.
- PV self-consumption - the storage system utilizes surplus production, especially where export to the grid is limited.
Sometimes the best decision is... not to buy a storage system now. In one case, the plant's profile yielded too little savings for the project to have priority - an investment in its own PV source had higher profitability, and the storage system was postponed for re-analysis. An honest advisor will tell you this straight out.
EMS, the brain of the storage system - what to ask the supplier
Even a well-sized storage system will earn less than promised if it is controlled by too simple a system. The analysis lists cases where the EMS had rigidly programmed charging hours instead of reacting to current prices, or carried out arbitrage exclusively without looking at the capacity fee - or exactly the opposite. Before signing the contract, it is worth asking:
- exactly what strategy the EMS implements and whether it is the same logic on which the offer was calculated,
- what happens in the event of loss of connectivity with the cloud - does the basic control operate locally,
- do you retain access to data, the history of algorithm decisions, and manual emergency mode,
- what do updates, backups, and security look like (including compliance with NIS2 cybersecurity requirements),
- who supports the system after commissioning and who will adjust the algorithm when tariffs or the plant profile change.
Where to start at your facility - hard data instead of a brochure
Two plants with similar annual consumption can get completely different results - profitability is determined by the hourly profile, tariff, contracted capacity, energy purchase model, and potential PV generation. Therefore, before anyone shows you a payback period, prepare the foundation:
- hourly measurement data from the meter (provided by the grid operator) and distribution invoices for the last year,
- the energy sales contract - its structure determines whether price arbitrage is available at all,
- connection and switchgear parameters as well as power reserves - this is the technical side that we check on site,
- data of the existing PV installation and its real production, if you already have one - along with the technical condition of the installation,
- measurements of the profile and power quality; if data is missing, a logger connected at the facility as part of a power quality analysis or energy audit will show how the plant actually draws power.
Our role in such projects is clearly defined: we provide hard measurement data and handle the electrical side of the investment - from connection verification, through integration of the storage system with the distribution board and existing photovoltaics, to commissioning measurements and documentation. The economic analysis of the variants should be done by an independent advisor using your data - not by an equipment salesperson using "typical" data. At the same time, it is also worth removing reactive energy charges from your bill - this is often the first and fastest saving in commercial electrical systems.
Are you considering energy storage or photovoltaics for your business? We will check the connection, the distribution board, and the consumption profile, and you will receive the measurement results in a format that any independent analyst can verify: write to us at kontakt@enertia.pl or call +48 459 566 991.
FAQ: energy storage in business - questions and answers
Is energy storage in a business actually profitable?
Very often yes - but not always and not in every configuration. The outcome is determined by the hourly consumption profile, tariff, contracted capacity, energy purchasing model, and potential photovoltaics. Two plants with similar annual consumption can get completely different results, which is why there is no answer without an analysis based on data from your meter.
The salesperson promises a payback in 2-3 years. Is this realistic?
Rarely. Such results do occur with an exceptionally favorable consumption profile, but in the cases described by industry media, the tables showing such a short payback period were based on unrealistic assumptions - battery operation without losses, no degradation, and omitted fixed costs. Ask for the assumptions and a conservative scenario; a reliable bidder will show them without hesitation.
What data should be prepared before discussing energy storage?
Hourly measurement data from the operator, distribution and energy sales invoices from the last 12 months, the energy sales contract, connection parameters, and PV production data if you have it. Any gaps in the data can be filled by recording the profile at the facility.
Does energy storage require increasing the contracted capacity?
Not always - and sometimes it is not worth it. Raising the contracted capacity means a higher fixed monthly fee throughout the lifetime of the project. In analyzed cases, a smaller storage system without changing the contracted capacity yielded a significantly higher rate of return than a larger one that forced this change. Always compare at least two or three sizing variants.
I already have photovoltaics. Where should I start?
By checking how much surplus production you are actually losing and what condition the installation is in - an inspection with measurements will show both safety and actual yields. Then, a profile analysis will answer whether the best first step is energy storage, PV expansion, or changing the energy purchasing model.
