BESS full form
BESS stands for Battery Energy Storage System. It is a system that stores electricity in batteries and releases it when it is needed. A BESS lets you use energy at a different time from when it was produced, for example storing solar power generated at midday and using it after sunset.
How does a BESS work?
A BESS works in two directions:
- Charging: when there is spare electricity, from solar panels or from the grid at off-peak times, the system converts it and stores it in battery cells.
- Discharging: when electricity is needed, for example in the evening, during a power cut or at peak tariff hours, the system converts the stored energy back into usable AC power for your home, facility or the grid.
Software decides when to charge and when to discharge, based on solar generation, electricity tariffs and demand.
The main parts of a BESS
- Battery modules: battery cells grouped into modules and racks that store the energy. Many of the systems NEXERA offers, including TCL BlueArk W10 and Hithium 261, use LFP (lithium iron phosphate) cells.
- Battery Management System (BMS): monitors cell voltage, current and temperature, balances the cells and protects the battery from unsafe conditions.
- Power Conversion System (PCS): converts DC power from the battery to AC power for use in your facility or on the grid, and converts AC back to DC to charge the battery.
- Energy Management System (EMS): the "brain" that decides when to charge and discharge, for example to shave peaks or use stored solar.
- Thermal management: liquid or air cooling that keeps cells within their ideal temperature range.
- Fire protection: multi-level detection and suppression designed to identify and isolate faults early.
Key terms, explained simply
Key term
kWh (kilowatt-hour), energy capacity: how much energy the battery can store. A bigger kWh number means it can supply power for longer.
Key term
kW (kilowatt), power rating: how fast the system can deliver energy at any moment. kW is how much at once; kWh is how much in total.
Key term
C-rate: how fast a battery charges or discharges relative to its capacity. At 1C a full battery discharges in about one hour; at 0.5C, in about two hours.
Key term
Depth of discharge (DoD): how much of the battery's capacity is actually used in a cycle, shown as a percentage.
Key term
Cycle life: how many charge-and-discharge cycles a battery can deliver before its capacity falls to a specified level.
Key term
Round-trip efficiency: the share of energy you get back out of the battery compared with what you put in.
Types of BESS by scale
- Residential (home) storage: stores rooftop solar for use in the evening and keeps essential appliances running during power cuts. Home battery storage
- Commercial & industrial (C&I) storage: helps factories, offices, hospitals and data centres with peak shaving, solar self-consumption and backup power. C&I battery storage
- Utility-scale storage: large containerised systems that support renewable integration, grid stability and peak demand. Utility-scale BESS
What is a BESS used for?
- Storing solar power and using it after sunset
- Backup power during outages
- Peak shaving: using stored energy at the times of highest demand to reduce demand-related costs
- Shifting energy use to cheaper tariff periods, where time-of-day tariffs apply
- Integrating more solar and wind into the grid
- Supporting grid stability
How to choose the right BESS
Start with four questions:
- How much energy do you need to store (kWh)?
- How much power do you need at once (kW)?
- What is it mainly for: solar self-consumption, backup, peak shaving or grid services?
- Where will it be installed: indoors, outdoors, on a rooftop or in a yard?
NEXERA's engineers help with sizing, system design and commissioning, with systems from TCL and Hithium.