Battery Energy Storage Systems (BESS)
A clear explanation of how a battery energy storage system stores and returns electrical energy, the main components and uses, and how storage pairs with solar and supports grid resilience in buildings.
A battery energy storage system (BESS) stores electrical energy when it is plentiful or cheap and returns it when it is needed or expensive. At its simplest it is a large rechargeable battery connected to the building or grid through power electronics, with a control system deciding when to charge and discharge. It lets energy be shifted across time, which is increasingly valuable as renewable generation grows.
For buildings, a BESS can store rooftop solar for use after sunset, provide backup during outages, shave expensive demand peaks, and support power quality. As the UAE expands solar generation and pursues net-zero goals, storage becomes the partner that turns intermittent sunshine into dependable, dispatchable energy.
How it works
Storing and releasing energy. A battery stores energy chemically. During charging, electrical energy drives a reaction that stores it; during discharging, the reaction reverses and releases electrical energy. The usable amount is the energy capacity (kWh), while how fast it can charge or discharge is the power rating (kW) — two separate numbers that together define what a BESS can do.
The battery and the inverter. Cells are grouped into modules and racks to reach the required voltage and capacity, usually as a DC system. A bidirectional inverter (power conversion system) converts between the battery’s DC and the building’s AC, both ways, and controls the rate of charge and discharge. This is the same family of power electronics used in solar inverters and drives.
The battery management system. A battery management system (BMS) is essential. It monitors the voltage, current and temperature of cells, keeps them balanced, prevents over-charge and over-discharge, and protects against conditions that could damage the battery or cause thermal runaway. The BMS is central to both performance and safety.
What a BESS is used for. Common applications include time-shifting solar energy to the evening, peak shaving to cut demand charges, backup power during outages, and improving power quality and supply stability. The control system selects the mode based on tariffs, solar output, load and grid conditions.
Safety and integration. Because batteries store concentrated energy, a BESS needs careful fire and thermal protection, ventilation, isolation and monitoring, and must be sited and protected to recognised standards. It is integrated with any solar, the building distribution and the management system so charging, discharging and protection work together safely.
Main types
In the UAE
- As the UAE rapidly expands solar generation, storage is increasingly used to shift daytime solar into the evening peak and support the grid, in line with national net-zero and energy-strategy goals.
- Grid-connected storage must meet the connection, protection and metering requirements of the distribution authority (such as DEWA or ADDC), including safe interaction with the grid.
- Battery installations must be sited and fire-protected to recognised standards, and the Gulf's high ambient temperatures make thermal management and ventilation especially important for safety and battery life.
How GPR applies this
GPR designs and installs battery energy storage for buildings across Abu Dhabi, sizing energy and power capacity to the application — solar time-shifting, peak shaving or backup — and integrating the inverter, battery management and energy-management systems. We engineer the fire protection, ventilation, isolation and monitoring the technology demands in the Gulf climate, coordinate grid-connection and metering with DEWA/ADDC, and tie storage into rooftop solar and the building management system for safe, optimised operation.
Frequently asked questions
What is a battery energy storage system?
A large rechargeable battery connected through power electronics that stores electrical energy when it is plentiful or cheap and returns it when it is needed or expensive, under the control of a management system.
What is the difference between energy capacity and power rating?
Energy capacity (kWh) is how much energy the system can store; power rating (kW) is how fast it can charge or discharge. Together they define what the BESS can do.
Why does a BESS need a battery management system?
The BMS monitors and balances cells, prevents over-charge and over-discharge, and protects against conditions such as thermal runaway, making it central to both performance and safety.
How does storage help a solar installation?
It stores surplus daytime solar so it can power the building in the evening or during outages, turning intermittent generation into dependable, dispatchable energy.
What is peak shaving?
Discharging the battery during periods of high demand to reduce the building’s maximum demand, which can lower demand charges and ease stress on the supply.