MW vs MWh: power and energy explained
20 minModule 2
Battery energy storage, explained
How grid batteries work, in plain language.
BESS Talk explains battery energy storage systems from the basics up: what is inside the container, how a battery earns money, and what it takes to keep one running for 15 years.
One day in the life of a battery Illustrative
State of charge (left axis) Electricity price (shape only)
Start here
Learn BESS in five steps
New to energy storage? Read these in order. Each one builds on the last, from the basic idea to running a real plant.
- Step 1
What is a BESS?
Why the grid needs batteries, and what one actually looks like on site.
- Step 2
MW vs MWh
Power and energy are different things. Get this right and the rest gets easier.
- Step 3
Inside the container
Cells, racks, the PCS, cooling and the EMS, and what each one does.
- Step 4
How a battery earns money
Energy trading, grid services and capacity payments, explained simply.
- Step 5
Keeping it running
Maintenance, availability and warranties over a 15-year life.
Topics
Basics first, then go deeper
The first two topics are for beginners. The last three are for people who already work with storage, or want to.
Basics
Storage 101
Key ideas and terms, with no prior knowledge needed.
Basics
Technology
Batteries, inverters, cooling and control systems.
Deeper
Markets & money
Revenue streams, business models and the German market.
Deeper
Operations & service
O&M, availability, spare parts and warranty claims.
Deeper
Safety & rules
Fire safety, grid codes and the EU Battery Regulation.
Modules
All modules First modules
Structured lessons you can work through at your own pace, from the basics up.
What is a battery energy storage system?
15 minModule 1
What is round-trip efficiency?
20 minModule 3
How does a battery make money in Germany?
30 minModule 4
What does availability mean for a BESS?
25 minModule 5
What happens during BESS maintenance?
25 minModule 6
Free tool
How big is that battery?
Projects are described in MW and hours. Move the sliders to see how much energy that is, how many homes it could supply for a day, and roughly how many containers it takes.
Glossary
Full glossary BESS words, decoded
The terms you will meet in every datasheet and contract.
- State of charge SoC
- How full the battery is, as a percentage of its usable capacity.
- C-rate
- How fast a battery charges or discharges compared with its size. 0.5C means a full charge in two hours.
- Round-trip efficiency RTE
- The share of energy you get back out after storing it. Some is always lost as heat.
- Power conversion system PCS
- The inverter that turns the battery's DC power into AC power for the grid, and back.
- Energy management system EMS
- The software that decides when the battery charges and discharges.
- Availability
- The share of time a plant is ready to run. Service contracts often guarantee it.
About
Why BESS Talk exists
Battery storage is one of the fastest-growing parts of the energy transition, but most explanations are written for specialists. BESS Talk starts from zero and builds up, in clear language, so anyone curious about storage can follow along. Based in Wolfsburg, Germany.