What is a BESS?

A BESS (or Battery Energy Storage System) is a type of energy storage system that captures energy from various sources and stores it in rechargeable batteries for future use. Depending on their capacity, measured in kilowatt-hours (kWh), and their power, measured in kilowatts (kW), they can be used to power a wide range of applications, supplying energy to homes, vehicles, industrial facilities and businesses. Although in some cases they can operate in isolation, they are usually connected to the distribution network.

What is the difference between BESS and ESS?

Both BESS and ESS are acronyms that stand for Battery Energy Storage System (BESS) or Energy Storage System (ESS) respectively. Their main difference is that BESS systems use electrochemical batteries as a storage medium, while ESS is a more generic term, which does not distinguish the medium used to store energy, whether chemical, thermal, kinetic or gravitational.

What is a BESS for?

Its main function is to store electrical energy for later use at other times of greater need. This translates into a contribution of flexibility to the installation that integrates it, whether local or national electric system, since it allows balancing generation and demand in an efficient way.

What are the benefits of using BESS?

The use of BESS offers multiple benefits:

• Economic benefit, for example, providing storage to a self-consumption photovoltaic installation, would allow storing surplus energy for later use at the time of production, where production is low or zero. This allows savings by reducing or avoiding the purchase of energy in periods of high demand and higher prices. Or also generating income by shifting the sale of surplus energy to the moment when the purchase price is higher.
• Technical benefit, for example, using storage to increase the power available at an access point with network congestion or when the increase in contracted power requires a costly expansion of the distribution network infrastructure. This can occur in gas stations/electroline stations, which, when they want to incorporate electric vehicle chargers, find that they do not have enough power for fast charging, which has an impact on the charging time of their customers.
• Environmental benefits, by allowing greater use of renewable generation, which reduces dependence on fossil fuels. On a technical level, they are a viable substitute for combined cycle turbines, which are currently used to support the grid during peak demand, but are greenhouse gas emitters. In addition, compared to other traditional storage methods, such as hydraulic pumping, BESS have a lower environmental impact by requiring less space, less water consumption, less landscape impact and less impact on the surrounding flora and fauna.

How are BESS storage systems classified?

Depending on their performance, BESS storage systems can be divided into sectors:

• Grid, with capacities ranging from 5MW to hundreds of MW. They provide flexibility to the transmission grid by balancing generation and demand.
• Commercial and Industrial, from 30kW to 5MW. In facilities such as hospitals, universities, public sector or large shopping centers, among others.
• Residential, for domestic applications with power between 3 and 15kW. Higher powers can also be used in shared self-consumption or small companies.

Vector Energy already offers a Residential Storage solution with its range of SUNVEC Hybrid Inverters. With single-phase inverters of 3, 5 and 7.5kW and three-phase inverters of 5, 10 and 15kW. Both versions are compatible with two battery models; the 3kWh SUNBAT-30, for configurations up to 12kWh. The SUNBAT-58 of 5.8kWh, for configurations up to 23.2kWh.

The optimal application of a BESS will depend on its scale and this is linked to its connection point with respect to the public distribution network:

• In-Front-of-the-Meter: (In-Front-of-the-Meter) For large-scale applications where storage participates in wholesale markets or provides support services (or ancillary services).
• Behind-the-Meter: For residential, commercial or industrial applications, where the storage is located within a private network, behind the utility meter.

Why install a BESS in industrial installations?

The price of energy is a determining factor, especially for large industrial consumers with production processes.

High or unpredictable energy costs affect the competitiveness of the production plant, so more and more companies are implementing energy efficiency measures. In many cases, renewable generation, such as photovoltaic roofs, has been installed to reduce energy costs. The next step is to incorporate storage in these installations to obtain the following benefits:

• Increased operational flexibility (use energy when required)
• Greater use of surpluses (reduction of exports)
• Lower transmission losses
• Better grid quality
• Increased security of supply.
• Lower carbon footprint

What are the most common batteries in the new BESS?

The most common Energy Storage Systems (ESS) are those using electrochemical batteries, particularly lithium-ion based cells due to their energy density and efficiency. The configurations currently used:

• NMC (lithium-nickel-cobalt-aluminum oxide or LiNiMnCoO2)
• NCA (lithium nickel-cobalt-aluminum oxide or LiNiCoAlO2)
• LTO (lithium titanate or Li4Ti5O12)
• LFP (lithium iron phosphate or LiFePO4)

The latter, despite not being the best in terms of technical performance, has a satisfactory performance in stationary applications and is one of the safest thermally, as it does not overheat as much and does not release oxygen during combustion. This has favored their adoption for both stationary and electromobility applications.

What changes are expected for the BESS in 2024?

Over the next 12 months, changes are expected in the Spanish electricity market, such as a new Capacity Market, and new storage auctions are also being considered for both new and existing facilities. This will offer new, more stable and predictable payback paths, which will stimulate investment and profitability of these technologies.

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