Batteries Transform Solar Into Permanent Electricity
108 gigawatts of storage capacity installed globally in 2025, eleven times more than in 2021. These figures from the International Energy Agency document a major shift: 90% of batteries now serve temporal shifting — storing solar electricity during the day and returning it at night. The main use of grid stabilization is finished. Batteries are pushing solar into the night and redrawing the world’s energy geography.
The mutation is accelerating. Annual additions climbed 40% in 2025, driven by China capturing 60% of new installations. Costs have been divided by ten over fifteen years, making this transition economically irresistible.
The Essentials
- 108 GW of storage capacity added in 2025, a +40% increase compared to 2024
- Global capacity multiplied by 11 since 2021, now reaching 347 GW
- 90% of batteries used for temporal shifting, versus a majority for grid stabilization five years ago
- China represents 60% of global additions in 2025
- Lithium-ion battery costs divided by 10 between 2010 and 2025
Temporal Shifting Becomes the Dominant Use
Energy storage was changing function. In 2020, most installed batteries served stabilization — compensating for micro-variations in the electrical grid, smoothing consumption peaks. Five years later, 90% of newly installed capacity aimed at temporal shifting: absorbing solar electricity during the day, when production exceeds consumption, and returning it in the evening.
This functional shift reflects a new problem. In states like California or South Australia, midday solar production regularly generates negative prices on the electricity market. Producers pay to dispose of their surplus. Storing this free or cheap electricity to sell during peak hours becomes more profitable than any other application.
Arizona illustrates this mutation. The state installed 2.3 GW of storage in 2025, almost exclusively coupled to solar farms. Electricity stored at 1 p.m., when solar floods the grid, sells for $180 per megawatt-hour at 7 p.m. The price difference justifies the battery investment, even including their replacement costs.
This temporal shifting strategy revolutionizes the solar economy. Gone are photovoltaic parks limited by intermittency. New installations systematically combine panels and batteries to provide electricity available 12 to 16 hours per day. Solar is leaving its daytime niche to compete with thermal power plants on their own ground: supplying electricity on demand.
China Monopolizes Global Additions
The 65 GW installed by China in 2025 represents 60% of global additions, far ahead of the United States (18 GW) and the European Union (12 GW). This Chinese dominance extends beyond simple production: Beijing controls 85% of global lithium-ion battery manufacturing and possesses 70% of refined lithium reserves.
The Chinese strategy blends public support and economies of scale. Provinces subsidize storage installation coupled to solar parks, guaranteeing a domestic market for local manufacturers. CATL, BYD, and EVE Energy — the three Chinese giants — dominate global contracts thanks to prices 40% lower than their American or European competitors.
This advantage feeds on massive investments. China invested $89 billion in battery research between 2018 and 2025, compared to $23 billion for all of Europe and the United States combined. Result: Chinese LFP (lithium-iron-phosphate) batteries now reach 6,000 charge-discharge cycles, compared to 4,000 for the best Western batteries.
Europe attempts resistance through regulation. The Battery Regulation, which entered into force in 2024, imposes environmental standards that only European producers currently meet. But these technical barriers barely slow the Chinese invasion. Northvolt, the European champion, produced 38 GWh in 2025 — less than CATL in six weeks.
The United States is betting on the Inflation Reduction Act to relocalize production. Tax credits for “Made in America” batteries reach $45 per kWh, or 15% of total cost. Ford, GM, and Tesla are building their own factories, but scaling up will take five to seven years. Until then, Chinese dependence is taking root.
Costs Collapse and Change the Game
Lithium-ion batteries cost $1,200 per kWh in 2010. They cost $120 in 2025. This 90% drop transforms global energy economics: storing electricity becomes cheaper than transporting it over long distances.
Bloomberg NEF attributes this deflation to four factors. Increased production volumes enabled massive economies of scale: global manufacturing capacity grew from 50 GWh in 2015 to 1,100 GWh in 2025. Chemical innovations optimized energy density: current batteries store 60% more energy than their 2020 equivalents. Production line automation reduced labor costs by 70%. Finally, vertical integration — from lithium extraction to final assembly — eliminated intermediate margins.
This cost decline redraws the energy geography. Countries rich in sunshine can now export their sun-stored electricity rather than their hydrocarbons. Australia is testing the export of sun-recharged batteries to Singapore. Morocco is studying “electron farms” combining massive solar with storage to supply Europe.
But deflation is reaching its limits. Raw materials — lithium, cobalt, nickel — now represent 70% of total battery costs, compared to 50% in 2020. Yet their prices are surging: lithium carbonate tripled between 2021 and 2025, driven by automotive demand. China is industrializing the humanoid robot while Tesla is still experimenting with it, but this industrial innovation race also increases pressure on critical resources.
Manufacturers are diversifying their sources and chemistries. CATL is developing sodium-ion batteries, 40% cheaper than lithium but with 20% less energy density. Tesla is testing iron-air batteries for stationary storage, virtually inexhaustible but heavier. These alternatives will slow cost increases without reversing them: the era of plummeting prices is ending.
The Geopolitical Impact of Distributed Storage
Massive electricity storage reshuffles geopolitical cards. Countries that import fossil energy can now target electrical self-sufficiency by coupling renewables and batteries. India is installing 22 GW of storage in 2025, targeting 40% renewable electricity by 2030 — compared to 12% in 2020.
This electrical autonomy weakens traditional exporters. Saudi Arabia, aware of the risk, is investing $180 billion in the Neom project: producing green hydrogen from massive solar and storage. The kingdom is attempting to substitute hydrogen for oil as an energy export vector.
But distributed storage poses new security challenges. A grid powered by millions of residential batteries becomes vulnerable to coordinated cyberattacks. South Korea experienced a three-hour outage in September 2025 caused by malware that simultaneously discharged 200,000 residential batteries. The incident reveals security gaps in decentralized electrical grids.
States are rethinking energy sovereignty. Germany has banned Chinese batteries from its critical infrastructure since January 2025, fearing electronic backdoors. France imposes a security audit for any storage system exceeding 10 MW. These defensive measures slow deployments but testify to growing awareness: controlling your batteries means controlling your electricity.
Storage Redefines Supply-Demand Balance
The multiplication of batteries transforms the daily management of electrical grids. Operators no longer simply pilot supply to follow demand. They now orchestrate three flows: production, consumption, and storage-destocking. This new complexity requires predictive algorithms and redesigned electricity markets.
RTE, the French grid operator, modified its market rules in 2025 to integrate batteries. Producers can now sell “deferred” electricity: stored today, delivered tomorrow. This forward electricity market attracts financial investors. Goldman Sachs raised $2.1 billion for a fund dedicated to “electricity arbitrage”: buying cheap electricity to store and reselling it at price peaks.
This financialization of storage concerns regulators. In California, 15% of storage capacity already belongs to speculative funds that optimize returns without considering grid stability. The regulatory authority CPUC has imposed public service obligations on battery owners since October 2025: obligation to discharge in emergencies, even if market prices remain low.
Mass storage also modifies electricity consumption. Households equipped with residential batteries shift energy-intensive uses — washing machines, dishwashers, electric vehicles — to off-peak hours to maximize self-consumption. This demand flexibility reduces peak production capacity needs, but complicates consumption forecasting.
Tesla reports that its Powerwall customers consume 23% less grid electricity than before installation, while maintaining the same comfort. This automated optimization — guided by artificial intelligence — foreshadows the emergence of autonomous consumer-producer-storer actors. Electrical grids are evolving from a centralized model toward an ecosystem of interconnected prosumers.
The accumulation of storage questions the future of thermal power plants. In South Australia, a storage pioneer state, gas plants operate only 15% of the year, compared to 60% in 2020. Their profitability collapses: generating electricity a few hours per year no longer covers fixed costs. Several operators are requesting public subsidies to maintain these “backup plants” essential for renewable failures.
This mutation questions the very structure of electricity markets. Designed for a world where production followed demand, they adapt poorly to a universe where storage decouples the two temporally. Europe is working on a reform of the electricity market that would integrate the “time value” of electricity: the longer it can be stored, the more expensive it is. First implementation planned for 2027, to prevent economic collapse of the traditional electricity sector.