Half the World's Power Capacity Is Renewable. That Is Not the Same as Half Its Electricity

by Arjun Mehta · September 14, 2026

Science & Technology Writer, The Globe Ledger

Two authoritative numbers about the world's electricity system circulated this year, and read side by side they appear to contradict each other. The International Renewable Energy Agency reported that renewables made up 49.4 per cent of global installed power capacity at the end of 2025. The International Energy Agency reports that variable renewables — solar and wind — supply 17 per cent of the world's electricity generation.

Both are correct. They measure different things. Capacity is a rating; generation is a count of what came out. Confusing the two is the single most common error in public discussion of the energy transition, and it runs in both directions: as an overstatement of how far the shift has gone, and as a dismissal of how fast it is moving.

IRENA's definition of what it counts is precise and worth reading slowly. In its Renewable capacity statistics 2026, dated 31 March 2026, the agency states that "the renewable power capacity data shown in these tables represents the maximum net generating capacity of power plants and other installations that use renewable energy sources to produce electricity."

"Maximum net generating capacity" is a ceiling, not an average. It describes what a plant can deliver to the grid under rated conditions after its own consumption. Nothing in the figure says how many hours a year the wind blows at the turbine, how often the sun is on the panel, or whether the transmission line out of the site was full when it did.

On that basis IRENA put total global renewable power capacity at 5,149 GW at the end of 2025, following additions of 692 GW during the year — growth of 15.5 per cent. Solar accounted for 2,392 GW of the total after adding 511 GW, a rise of 27.2 per cent. Wind stood at 1,291 GW after adding 159 GW, up 14.0 per cent, and renewable hydropower at 1,296 GW. Bioenergy reached 154 GW, geothermal 16 GW and marine energy 0.5 GW.

The agency also reported that renewables accounted for 85.6 per cent of all power capacity added in 2025, with solar and wind jointly accounting for 96.8 per cent of net renewable additions. IRENA does not publish solar and wind as a share of all installed power capacity, but its own figures imply one: 2,392 GW plus 1,291 GW is 3,683 GW, and if the 5,149 GW renewable total is 49.4 per cent of everything installed, the world's total fleet is about 10,400 GW. Solar and wind are therefore roughly 35 per cent of installed capacity. That arithmetic is ours, not IRENA's, and it is the figure to hold against the IEA's generation share.

The IEA's Electricity 2026 report carries no publication date on the page consulted; it was accessed on 14 September 2026. It records that variable renewables supply 17 per cent of global electricity generation, and forecasts that share reaching 27 per cent by 2030. Renewable generation is expected to grow by roughly 1,000 TWh a year to 2030, with solar photovoltaics alone accounting for over 600 TWh of that. Renewables and nuclear together, the IEA expects, will account for around half of global electricity generation by 2030.

So roughly a third of the machines, and roughly a sixth of the electricity. The gap is not an accounting failure. It is physics and scheduling. A solar farm rated at one gigawatt produces nothing at night and less than its rating in most daylight hours; a gas turbine rated at one gigawatt can in principle run whenever it is dispatched and fuelled. The rated numbers are directly comparable; the output they imply is not.

This is why capacity-based targets need careful handling. The COP28 goal, as IRENA records it, is to "triple installed renewable power capacity to more than 11 TW by 2030." IRENA sets its end-2025 cumulative figure of 5,149 GW against an 11.17 TW marker in its 1.5°C Scenario — a shortfall of a little over 6 TW on that arithmetic. That is a target expressed in machines, and hitting it does not by itself specify how much electricity results.

IRENA's boundaries matter too, and the agency states them. Stationary electric batteries are excluded from the 5,149 GW total because, in its words, data collection for them is still at an early stage. Pure pumped storage hydropower — 160 GW — is reported separately rather than inside the renewable hydropower line, so that hydropower including pumped storage comes to 1,456 GW. Off-grid capacity is counted apart from grid-connected capacity and stood at 17.8 GW at the end of 2025, having expanded by 1.7 GW during the year.

Those exclusions are defensible and consequential. Batteries do not generate energy; they move it in time. But in a system where a third of capacity is weather-dependent, the ability to move electricity from a sunny afternoon to a still evening is part of what converts capacity into delivered supply. A capacity table that omits storage is not wrong, but it is describing only one half of the machine.

The geography of capacity is heavily concentrated. IRENA's end-2025 highlights place Asia at 2,895 GW, or 56.2 per cent of the global total, after adding 514.1 GW during the year — 74.2 per cent of all new capacity worldwide. Its detailed tables put Europe at 934 GW and North America at 614 GW, with Africa at 82 GW, the Middle East at 56 GW and Central America and the Caribbean at 21 GW. The regions with the least installed capacity are not generally the regions with the least sun.

IRENA is also candid about provenance. Its data comes from the IRENA questionnaire, official statistics, industry association reports, and other reports and news articles, and each entry is flagged as official, unofficial or an IRENA estimate. Figures are given in megawatts rounded to the nearest one. A reader can see, line by line, how firm a given country's number is.

On the generation side, the IEA's framing puts the capacity build in context. Global electricity demand grew 3 per cent year on year in 2025 and is forecast to rise at an average of 3.6 per cent a year over 2026 to 2030. Renewable output rose rapidly in 2025, on the IEA's account virtually matching the level of coal-fired generation on the latest available data, while global power sector emissions remained flat in 2025 and are forecast to plateau over 2026 to 2030.

That last pairing is the honest summary of where things stand. Capacity is being added at a rate that changes the composition of the fleet quickly; generation shares move more slowly because demand is growing underneath them and because each new gigawatt of solar delivers fewer hours than a gigawatt of thermal plant. Flat emissions alongside record capacity additions is exactly what that arithmetic produces.

For readers, the rule is simple enough to apply. If a figure is in gigawatts or terawatts, it is describing installed machinery and the year it was connected. If it is in terawatt-hours or as a share of generation, it is describing electricity that actually reached the grid. Neither number is a proxy for the other, and the distance between them is the part of the transition that grids, storage and demand patterns still have to close.