What is a battery storage system?
A battery storage system or a battery energy storage system (BESS) is a device that allows you to store renewable electricity for a time when you really need it.
How does it work?
Essentially, a battery storage system operates similarly to a battery, although it’s slightly more advanced. These systems can be connected to the grid, or a renewable energy source generating wind or solar power, and subsequently storing that energy for later use when necessary.
The charging phase
Getting into the technicalities of it all, a battery storage system begins by converting electrical energy from the power source, into chemical energy for storage. Since a battery consists of electrodes (anode and cathode) and an electrolyte, a chemical reaction follows during the charging phase which includes the free movement of ions and electrons.
What does a battery storage system consist of?
A battery storage system is built from several components that efficiently allow for the charging, management and deployment of electrical energy. These components include:
- Battery cell
- Battery management system (BMS)
- Energy management system (EMS)
- Thermal management system
- System controller
- Protection device
- Housing
- Communication system
Battery cell
A fundamental component of a battery is arranged in racks, which stores chemical energy and converts it to electrical energy.
Battery management system (BMS)
A system that protects the battery from overcharging, over-discharging, short-circuiting or overheating and subsequently from damaging itself. It does so by monitoring the battery and controlling its performance.
Energy management system (EMS)
Controls and manages the flow of energy through the system, during the charging and discharging phase for the optimisation of the battery’s life and overall viability of the system.
Thermal management system
Keeps the thermal energy (temperature) of the battery under a certain threshold by providing cooling to prevent overheating and consequently degradation or malfunction of the battery.
System controller
Controls the smooth operation of the battery cell by monitoring charging and discharging levels. It does so by implementing overload protection during charging and reverse power protection during discharging to prolong life-expectancy.
Protection device
Protects the system from electrical faults like short circuits or overloads and controls the flow of current in the system.
Housing
The external housing unit of the battery system. It shields the system from environmental factors like rain, extreme temperatures and UV radiation. Many systems also include fire suppression features as an added measure.
Communication system
Enables communication between the battery storage system and external systems, such as a utility grid or energy management software.
Types of Battery Storage Systems
- Lithium-Ion Batteries
- Flow Batteries
- Lead-Acid Batteries
Lithium-Ion Batteries (Li-Ion)
Perhaps the type of battery that’s most common in battery storage systems. Although they were first popularised in electric vehicles (EV), they have gradually transitioned to residential solar energy systems and large-scale grid applications. Lithium-ion batteries share a high-energy density, meaning large amounts of energy can be stored in a small area. In addition, they also feature high efficiency and charge/discharge rates, and a long lifespan, making them more cost-effective over their lifetime.
Flow Batteries
Flow batteries use external tanks to store energy through liquid electrolytes. Its capacity is dependent on the size of the electrolyte storage tanks so it can be scaled for purpose. They are less sensitive to fluctuations in temperature and endure a long lifespan, however, they are expensive to install and can discourage its use through their complex maintenance requirements.
Lead-acid Batteries
Lead-acid batteries have stood the test of time with their impact on the automotive industry. They are the go-to choice for car batteries and have transitioned to emergency power systems and off-grid energy storage. They are widely available, reliable, inexpensive and can operate in a large temperature window. Though they can have a shortened lifespan and require regular maintenance to perform effectively.
Applications of Battery Storage Systems
- Residential
- Commercial and Industrial
- Grid-Scale Applications
Residential
The residential market is seeing the practicality of storing and using renewable energy to power their homes. Coupling solar PV panels with battery storage technology, allows owners to generate excess solar energy during the day, for use during evenings, periods of high energy demand or even blackouts. Such flexibility, allows owners to potentially reduce their reliance on the grid and save on costs by minimising their energy bills.
Commercial and Industrial
Commercial and industrial spaces opt for larger battery storage systems to suit the energy requirements of a particular business. Such a system allows businesses to reduce their reliance on the grid, minimise peak demand charges, and lower overall energy costs. Furthermore, it allows for peak shaving (reducing the amount of electricity acquired from the grid at periods of high demand) and load shifting (moving energy consumption from peak demand times to periods of lower demand).
Grid-Scale Applications
Large-scale energy storage systems are known as grid-scale battery storage systems that support and stabilise the electrical grid. Grid-scale storage becomes increasingly important as renewable energy sources like solar and wind grow in popularity to preserve the efficiency and dependability of the grid. These systems are usually found at power plants, substations, or big utilities and play a crucial role in energy infrastructure.
Benefits of Battery Storage Systems
- Less dependence on the grid
- Peak-load shifting
- Future cost savings
Lower dependence on the grid
With a battery storage system, you can be on your way to achieving energy independence by storing energy for when it's needed most. Instead of feeding the energy back into the grid when there has been an energy surplus, a battery storage system can store it for a time when renewable energy generation isn’t available.
This excess energy can be utilised during high-demand periods when electricity prices or grid demands are high.
Peak-load shifting
This energy management strategy uses stored energy to shift the energy demand from peak times to off-peak times where energy demand and prices are cheaper. By doing so, the stored energy is used during peak hours thus reducing the amount of power being drawn from the grid.
Future cost savings
By enabling users to store electricity during periods of low electricity prices and use it during periods of high demand, bills can be minimised through lower reliance on more costly grid power.
