Energy storage fundamentally improves the way we generate, deliver, and consume electricity. Energy storage helps during emergencies like power outages from storms, equipment failures or accidents. But the game-changing nature of energy storage is its ability to balance power supply and demand instantaneously which makes power networks more resilient and efficient.
An Energy Storage System that you own is your answer to greater grid independence, reduced significantly electrical costs and grid casualty preparedness. It will support your renewable energy system by storing the energy you generate during the day for use in the evening or whenever your peak demand period occurs.
in addition, with energy storage, you can take full advantage of the daily fluctuations in the price of electricity by purchasing electricity at the cheapest price of the day and consuming stored electricity during the most expensive hour of the day.
And last but not least. As an energy storage owner, you can participate in the electricity grid frequency reserve market by offering frequency control capacity to the transmission system operator, which pays a daily variable price for the control reserve offered to the energy storage operator.
The electricity grid frequency reserve market is by far one of the best uses and sources of revenue for energy storage.
We are often asked what the price of a 1MW energy storage is.
The answer can be anything between 500k€ and € 5M€.
In reality, the price of an energy storage is determined by its capacity, ie the amount of energy in the battery, which is defined as kWh or MWh.
The product development and cost level of Li-Ion batteries are falling all the time, and with it the prices of energy storage systems are falling. Slower in small systems than in large systems. It can be said that the average price of energy storage equipment ranges from € 320 to € 700 kWh depending on the size of the system, the characteristics of the energy storage and the state of the art.
It is always a good idea to look at what kind of energy storage will be used and what power / energy ratio would be optimal to get the optimal return from energy storage.
Rated power capacity is the total possible instantaneous discharge capability in kilowatts (kW) or megawatts (MW) of the BESS, or the maximum rate of discharge that the BESS can achieve, starting from a fully charged state.
Energy capacity is the maximum amount of stored energy in kilowatt-hours (kWh) or Megawatt-hours (MWh). The energy capacity is often given as the so-called DC nominal capacity, which is the actual capacity of the Li-Ion battery at the battery terminals. Size DC nom. however, the capacity is not usable in the whole system, but the actual usable capacity is often described as the so-called AC nominal capacity which takes into account the battery operating window (which is generally 90-95% of the battery DC rated capacity) and the DC-AC-DC conversion efficiency (which is between 95-98%). As a rule of thumb, it can be said that the available AC system nom. the capacity is about 90% of the nominal capacity of the battery.
Storage duration is the amount of time storage can discharge at its power capacity before depleting its energy capacity. For example, a battery with 1 MW of power capacity and 2 MWh of usable energy capacity will have a storage duration of two hours.
Cycle life/lifetime is the amount of time or cycles a battery storage system can provide regular charging and discharging before failure or significant degradation.
Self-discharge occurs when the stored charge (or energy) of the battery is reduced through internal chemical reactions, or without being discharged to perform work for the grid or a customer. Self-discharge, expressed as a percentage of charge lost over a certain period, reduces the amount of energy available for discharge and is an important parameter to consider in batteries intended for longer-duration applications.
State of charge, expressed as a percentage, represents the battery’s present level of charge and ranges from completely discharged to fully charged. The state of charge influences a battery’s ability to provide energy or ancillary services to the grid at any given time.
Round-trip efficiency, measured as a percentage, is a ratio of the energy charged to the battery to the energy discharged from the battery. It can represent the total DC-DC or AC-AC efficiency of the battery system, including losses from self-discharge and other electrical losses. Although some battery manufacturers refer to the DC-DC efficiency, which does not describe the actual capacity of the system. AC-AC efficiency is typically more important to Energy Storage System operators, as they only see the battery’s charging and discharging from the point of interconnection to the power system, which uses AC.
The energy storage is very maintenance-free and requires little maintenance.
In principle, there are no moving parts in the energy storage that have consumables. Depending on the implementation solution, the cooling system is practically the only one that requires annual maintenance, which is mainly related to the replacement and cleanliness of the filters.
Very often energy storage has given a lifespan of about 10 years.
That’s a good rule of thumb, but still a little misleading because what matters is that what are the applications for which the energy storage is used and how many daily charge / discharge cycles are required of the energy storage.
On average, today (2022) batteries are capable of about 6000-8000 full charge / discharge cycles, after which their charge level has dropped to about 70% of the original level and they reach the end of their service life in energy storage applications.
It is often thought that as much as 6000-8000 cycles (or ten years) is the total lifespan of an energy storage, but that is not the case.
The energy storage itself is a equipment to which the battery can be easily replaced when it reaches its service life. In next 10 years, for example, the price of batteries will be only a fraction of the current price level, which means that with a relatively low renewal cost, another 10-15 years of new service life can easily be obtained again.