A Guide to Battery Energy Storage Systems (BESS)
What is a Battery Energy Storage System (BESS)?
Battery Energy Storage Systems (BESS) have gained significant attention due to them offering 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 Energy Storage Systems, or BESS, are innovative energy storage solutions that store electrical energy in batteries for later use. They play a crucial role in power stability on grid or off grid optimising energy usage, and reducing emissions, fuel usage and providing additional capacity.
Main components of BESS:
- 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.
Common BESS terminology
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.