We talk a lot about solar and wind. About the thing that actually makes them usable, far too little: storage. Battery storage, known in the industry as BESS for Battery Energy Storage Systems, is the quiet backbone of the energy transition. And from an entrepreneur's point of view, one of the most exciting markets there is.
The core problem with renewables
Sun and wind do not deliver when we need electricity, but when nature decides to. At midday the sun shines, power is cheap, sometimes even in surplus. In the evening, when everyone comes home and consumption rises, it gets scarce and expensive. This gap between generation and consumption is the real hurdle for a power system built on renewables.
This is exactly where storage comes in. A battery storage system takes up cheap electricity when there is too much of it and releases it when it becomes scarce and expensive. It shifts energy across time. That stabilizes the grid, lowers prices, and is what makes renewables capable of carrying base load in the first place.
How fast this market is growing is clear from the numbers: in 2024 alone, installed storage capacity in Germany grew by around 50 percent according to the German Solar Association, reaching almost 30 gigawatt hours. A market that is multiplying within a few years.
The global trend is unmistakable
Germany is not a special case but part of a global wave. In its report, the International Energy Agency notes that the worldwide capacity of grid-scale utility batteries grew more than twelvefold between 2020 and 2024, see IEA. That is a rate of growth you rarely see in the energy sector, and it keeps accelerating.
The driver behind it is as simple as it is powerful: price. According to the same analysis, the cost of lithium-ion battery packs fell by around 20 percent in 2024 alone. What counted as expensive five years ago now pays off. And because what pays off gets built, the logic here is tipping: storage is no longer a subsidy line item but an investment case. That is exactly what makes the market interesting to me as an entrepreneur, not just as a technical topic.
Why this is a business model
The spread between cheap and expensive electricity is the return. Whoever stores power and feeds it back in at the right moment earns on exactly that difference. On top of that come revenues from grid stabilization, because storage can react in a flash, faster than any conventional power plant. A technical component turns into a tradable asset.
In concrete terms it looks like this: a storage system charges at midday, when solar power sometimes pushes the exchange price toward zero or even negative, and sells in the early evening, when peak prices are a multiple of that. At the same time, the same system offers its ability to deliver power within fractions of a second on the balancing-energy market, whenever the grid needs it. Two revenue streams from one asset, and both live on the fact that prices fluctuate. I describe how this interplay of power price, trading, and technology feels in more detail in energy trading meets AI on the power market.
And here is where it gets truly interesting for me: controlling these storage systems, when to charge, when to feed in, is a real-time optimization problem with many variables and constantly new data. In other words, exactly the kind of problem where AI and agentic systems make a real difference. A human cannot weigh weather forecasts, exchange prices, grid signals, and state of charge against each other second by second. A well-built system can.
Looking ahead
The expansion of renewables all but forces the expansion of storage. One does not work without the other. Whoever understands today how generation, storage, and intelligent control play together is watching one of the largest infrastructure markets of the coming years take shape. I am looking at this very closely, because it brings energy, finance, and technology together, my three fields at once.
Frequently Asked Questions
What is a battery storage system (BESS)?
A system that stores electricity when there is a lot of it and it is cheap, and releases it when it becomes scarce and expensive. It shifts energy across time.
Why is storage decisive for the energy transition?
Because sun and wind fluctuate. Storage bridges the gap between generation and consumption, stabilizes the grid, and makes renewables capable of carrying base load.
Why is this a business model?
The return lies in the price spread between cheap and expensive electricity, plus revenues from grid stabilization. The optimal real-time control is a task for AI.
How fast is the storage market growing?
Very fast. According to the IEA, the worldwide capacity of grid-scale utility batteries grew more than twelvefold between 2020 and 2024, driven by falling battery prices. In Germany, installed capacity rose by around 50 percent in 2024 alone.
Warm regards,
Dennis Weidner
