Energy storage for business - how to tell a reliable analysis from a 2-year payback promise

Energy storage (often referred to in offers as BESS, short for 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 photovoltaics. The problem is that it is much harder to calculate than a PV installation alone. And it is precisely this complexity that the weakest offers exploit.

Why the sudden surge in energy storage offers

The mechanism was recently described by the portal WysokieNapiecie.pl in an analysis prepared by an energy market advisor: the commercial PV market has saturated, so some salespeople who previously sold panels are now offering storage - often to the same clients. Many do this professionally. However, there are also active sellers whose only strategy is to promise a very short payback period, wrapped in charts and complex terminology.

The author of the analysis has compiled five cases from his consulting practice - ranging from verifying suppliers' offers to deciding whether to purchase a storage system at all. The conclusions are instructive for anyone who has just received a "2-year payback table" - which is why we summarise them below and add the perspective of a contractor 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 storage system operates neither without losses nor "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 them, the result only looks beautiful on paper.
• Calculating on annual totals - the profitability of a storage system is determined in the hourly profile, day by day. A single year calculated "on aggregated data" and projected 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 on 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 streams compete for power and capacity.
• Simple payback period instead of NPV and IRR - i.e. measures that show how much a 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 larger storage system does not always mean a better result

The most interesting thread of the analysis concerns the selection of the device size. In one of the described cases, a plant with a consumption of about 18 GWh per year was considering a 4 MW/8 MWh storage system - so large that it required increasing the contracted capacity. Fixed costs would consequently increase by one 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 per cent).

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 value of the investment. 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 vary significantly depending on the plant's profile:

• Capacity fee - shifting consumption outside peak hours reduces the multiplier used by the operator to calculate this fee, and is often the main source of savings. In the described chemical plant, a relatively small 200 kW/400 kWh energy storage system yielded a double-digit rate of return, primarily due to the capacity fee and reduced contracted capacity - even without price arbitrage.
• Contracted capacity - smoothing out consumption peaks sometimes allows for its reduction, which generates monthly savings. It also works the other way around: an oversized storage system can force you to increase it.
• Tariff zones and price profile - charging when energy is cheap and discharging during peak hours requires an energy purchase model that enables this. Companies bound by a multi-year fixed-price contract will not benefit from arbitrage without changing their contract - and this must be checked before purchasing, not after.
• PV self-consumption - the storage system manages surplus production, especially where export to the grid is limited.

Sometimes the best decision is... not to buy an energy storage system right now. In one case, the plant's profile yielded savings too small for the project to be prioritized - investing in their own PV source offered higher profitability, and the storage system was postponed for re-analysis. An honest advisor will tell you this directly.

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 a system that is too simple. The analysis lists cases where the EMS had rigidly programmed charging hours instead of reacting to current prices, or performed only arbitrage without considering the capacity fee - or vice versa. Before signing a contract, it is worth asking:

• what exact strategy does the EMS implement and is it the same logic used to calculate the offer,
• what happens if connection to the cloud is lost - does basic control operate locally,
• do you retain access to data, the algorithm's decision history, and manual override 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's 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:

1. hourly metering data from the meter (provided by the grid operator) and distribution invoices from the last year,
2. the energy supply contract - its structure determines whether price arbitrage is available at all,
3. parameters of the connection, switchgear, and power reserves - this is the technical side that we verify on-site,
4. data of the existing PV installation and its real production, if you already have one - along with the technical condition of the installation,
5. measurements of the profile and power quality if data is missing - a logger connected on-site 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 integrating the storage system with the switchgear and existing photovoltaics, to commissioning measurements and documentation. The economic analysis of variants should be done by an independent advisor using your data - not by an equipment seller using "typical" data. At the same time, it is also worth removing reactive power charges from your invoice - this is often the first and fastest saving in corporate electrical systems.

FAQ: energy storage in a company - questions and answers

Is energy storage in a company profitable at all?

Very often yes - but not always and not in every configuration. The result is determined by the hourly consumption profile, tariff, contracted capacity, energy purchase 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 seller promises a payback in 2-3 years. Is this realistic?

Rarely. Such results occur with an exceptionally favorable consumption profile, but in cases described by industry media, spreadsheets with such a short payback 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 metering data from the operator, distribution and energy supply invoices from the last 12 months, the energy supply contract, connection parameters, and PV production data if you have it. Any gaps in data are filled by recording the profile on-site.

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 project's lifespan. In the 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 do I start?

From checking how much surplus production you are actually losing and the condition of your system - an inspection with measurements will reveal both safety and actual yields. Then, a profile analysis will determine whether the best first step is energy storage, PV expansion, or changing your energy purchasing model.