A guide to Battery Energy Storage Systems (BESS)

A battery energy storage system (BESS) is a technology that allows for the storage of electrical energy in batteries, which can then be used to power electrical loads. BESS can be used for a variety of applications, including grid stabilisation, load shifting, backup power, and integration with renewable energy sources such as solar and wind power. BESS typically consists of a battery bank, power conversion systems, and control systems that manage the charging and discharging of the batteries. 

Battery Energy Storage Systems (BESS) have gained significant attention as they offer numerous benefits including reducing emissions, fuel usage and cost. However, this is a complex technology, and it is important to consider numerous factors before choosing the right BESS for your application. In this article, we discuss key terminologies and equipment needed for battery storage integration. By using batteries, we are helping our customers optimise their temporary power setups.

• Battery cells: Battery cells store electrical energy by converting it into chemical energy and are commonly assembled in modules and packs to meet the desired capacity.
• Inverters: These convert direct current (DC) energy to alternating current (AC). This allows electrical energy to be converted, stored, and reused.
• Controller: Controls the battery cells’ performance for safe operation. It also maintains the balance of charge and allows the BESS to be monitored remotely. Controls are key to how the BESS will operate with other assets.

Understanding key battery energy terminology is essential for effective utilisation. Here are some key terms:

• State of Charge (SoC): represents the current energy level of a battery. It is often illustrated graphically to provide a visual representation of the battery's charge status.
• Depth of Discharge (DoD): indicates the amount of a battery's capacity that has been used. 
• Round-Trip Efficiency (RTE): is expressed as a percentage and represents the ratio of energy recovered from the BESS compared to the energy input, accounting for losses such as heat.
• BESS cycle rate: how many times the BESS cycles each day (fully charges and discharges). 
• Max charging current: the maximum charging current for a BESS is determined by battery capacity, chemistry, and the charger or inverter used in the system.
• Hybridising: adding multiple power sources within a solution, this could be adding battery storage to a generator package solution or even to a solar package. A hybrid power package is made by combining two or more different forms of power.
• Pass-through limit: defines the maximum amount of energy that can flow through a BESS without being stored. The pass-through limit is a vital consideration when pairing a generator with a BESS.
• Spinning reserve: generating capacity that is active and prepared to provide immediate power during increases in power demand or unanticipated loss of other power sources.
• Spinning reserve displacement: using stored energy in batteries to replace or reduce the need for typical sources of spinning reserve such as generators.