Spain's solar struggle: Tesla ready to soak up the sun

Solar now supplies a quarter of Spain's electricity, double its share in 2022. But the more solar a market adds, the less each midday hour is worth: in Spain this year, midday power sold for a fifth of the evening price. The ones who profit are those who buy at midday and sell in the evening: the companies building batteries. The batteries being added to Spanish solar farms come almost entirely from Chinese makers, but two-thirds of the standalone capacity in Spain's permits, the batteries built only to trade that gap, is built on Tesla Megapacks. None of those batteries is running yet, and when they are, the evening margin will go to the companies that own them; Tesla's prize is the hardware and the software that trades it. The question is no longer whether Europe can build enough solar, but who gets paid for the power it produces.

What we measured

We analysed hourly day-ahead electricity prices in 44 bidding zones across 27 European countries, from 1 January 2022 to 20 October 2026, together with daily generation by source for each country. Prices for continental Europe come from the power exchanges via Energy-Charts, and for Great Britain from Elexon; generation for Great Britain comes from the National Energy System Operator. All hours are Central European Time, and 2026 figures cover the year to 20 October.

Italy, Norway, Sweden and Denmark are split into several bidding zones, each with its own price. We report each zone separately and name the zone wherever a country has more than one. For batteries, we read the equipment listed for every battery project in Spain's national gazette, the Boletín Oficial del Estado, and grouped the projects by maker and by whether they stand alone or sit beside a solar or wind farm.

We focus on two measures because they capture different sides of the same market:

The midday–evening gap compares the average day-ahead price between 11:00 and 15:00, when solar output peaks, with the average between 18:00 and 22:00, when solar falls away and demand peaks. It is the margin a battery captures by charging at lunchtime and selling in the evening, before efficiency losses.

Zero-price hours counts the hours in which the day-ahead price was zero or below. In those hours a generator selling on the market earns nothing for its power, or pays to deliver it.

A market can look moderate on one measure and extreme on the other. The gap shows what a battery can earn on an ordinary day; zero-price hours show how often a solar farm selling on the market goes unpaid. Both come from the same cause: more solar at midday than the market can use.

Where solar grows fastest, midday power is worth least

For anyone who sells solar power on the market, or plans to store it, such as the developers lining up Tesla Megapacks in Spain's battery permits, what matters now is how cheap midday power gets and how often it is worth nothing at all. In every zone outside the far north, power costs far more in the evening than at lunchtime, and that gap decides who earns from a megawatt-hour of solar power. A solar farm sells it at the midday price; a Tesla battery charges with it at midday and sells it in the evening, and keeps the difference. The chart below sets the two side by side in every country we track: where solar is plentiful the battery earns more, and in Spain it earns about four times as much as the farm that generated the power.

The midday price is where solar's effect shows most clearly, and it falls furthest wherever a country has added more panels than it can use in the middle of the day. Every solar farm produces in the same hours, so each new plant adds power when the market already has plenty, and pushes the midday price down for every plant selling into it. Once the sun sets, gas plants set the price again, and evening power costs what burning gas costs. In Spain, midday power averaged €22 per megawatt-hour this year, against €111 in the evening.

Part of the gap also stems from commercial reality. Spain added another 10 GW of solar in 2025, according to the industry association UNEF, and almost all of it sells into the same four midday hours. The country has almost no batteries yet to hold that power back for the evening, so the extra output has nowhere to go but the midday market, and each new farm lowers the price for every farm already selling there. Most Spanish solar farms sell their output at the market price rather than under a fixed-price contract, so the midday glut lands directly on their revenue.

Zero-price hours show how far the glut goes. In Spain the day-ahead price was zero or below in 41% of midday hours this year. For a solar farm without a fixed-price contract those are lost hours; for a battery they are the cheapest hours to charge, and the hours the Tesla Megapacks in Spain's permits are built to buy. After sunset zero-price hours all but disappear: across our zones, fewer than one evening hour in a thousand was priced at zero, so a battery that charges at midday always has an evening buyer.

Solar plays varied roles across Europe

Solar plays different roles across Europe's power markets. In some it now sets the midday price on its own; in others it adds to a system that still runs on nuclear, hydro or gas. Where batteries arrived early, as in Bulgaria, solar's cheap hours already have a buyer; where they have not, as in Spain, those hours wait for whoever builds the storage, which is the market Tesla is lining up for.

Our analysis covers the day-ahead markets of 27 countries, where solar is sold in the same auction as every other source. The chart below shows how large a share of each country's power solar now generates, from Energy-Charts and, for Great Britain, the National Energy System Operator. Most of that solar produces in the same midday hours, so the share is a fair guide to how much power arrives at once. It leaves out the Netherlands, where solar output is missing from our generation data, and the countries where our data does not cover every source.

In Iberia, solar has become the midday price-setter, and it now rivals wind and nuclear as Spain's largest source. Portugal, whose market is coupled to Spain's, sells at almost the same midday price, even though solar supplies a far smaller share of its own power. Spain counted 397 hours of negative prices, eight times as many as a year earlier, in the first quarter of 2026 alone, according to pv magazine: hours in which a battery would have been paid to charge. With almost none running yet, Iberia offers batteries the widest opening in Europe.

Germany has Europe's largest solar fleet, and its midday price drags its neighbours down with it: the regulator's SMARD platform counted 573 negative-price hours in 2025, and Belgium and the Netherlands, whose markets are coupled to Germany's, set records of their own. Unlike Spain, Germany already runs several gigawatts of batteries to buy those hours. France shows that solar does not need a large share to empty the midday market: it makes less than a tenth of French power, with EDF's nuclear plants supplying most of the rest, yet the grid operator RTE counted hundreds of negative hours, mostly around midday.

Central and South-East Europe has added solar fastest, from a low base, and pays for it in the evening. The six countries from Slovenia to Greece had 29 GW of solar in 2025, according to the EU regulators' agency ACER, while closing coal plants left too few flexible plants to replace solar after sunset; evening prices there are now the highest in Europe. Hungary's solar output passed national demand at noon on one day in June 2025, with barely any batteries to store it. Bulgaria moved first on storage: its grid operator counts more than 3 GW installed, and in the August 2026 heatwave Greece and Bulgaria, with batteries behind their solar, had the region's lowest prices.

In Italy and the Nordics, solar barely moves the price. Italy still burns gas for about half its power, so even its sunniest southern zones pay several times Iberia's midday price, and the grid operator Terna is buying storage by auction instead: its first MACSE auction awarded 10 GWh of batteries in September 2025, more than half of it to Enel. In Sweden and Norway, hydro and wind set the price, and northern Sweden's negative hours come from wind, not sun; there, midday and evening power cost almost the same. In Finland, where electric boilers soak up surplus power, evening power is among the cheapest in Europe. Great Britain sits in between: solar supplies a tenth of its power, and its midday power is cheaper than its evening power, but by far less than in Iberia. Where midday and evening cost almost the same, a battery has little to trade; the money sits where the gap is widest, in Iberia and the south-east.

Batteries are where the money is, and Tesla is lined up

A battery earns the gap between when it charges and when it sells. On Clean Horizon's index, what a battery earns in Spain nearly doubled between June and July 2026, yet Spain had less than 200 MW of batteries running in April, according to Red Eléctrica, while Germany, Italy and Great Britain each have several gigawatts. Tesla is moving into that gap across Europe. In June 2026 it signed a deal with NatPower to supply more than 25 GWh of Megapacks to projects in Italy and the UK, with trading through its Autobidder software, and Wood Mackenzie ranked it the world's largest battery integrator in 2024.

Spanish battery projects must publish their equipment in the national gazette, the Boletín Oficial del Estado. We read every battery filing in it and compared Tesla with every other maker named, separately for standalone batteries and for batteries added to solar and wind farms. Battery filings have multiplied since 2023, and 32 projects name the battery maker. Looking at who supplies them, a few patterns stand out:

Tesla leads standalone batteries: Megapacks make up two-thirds of the named capacity in standalone projects, and lead in both regions where they appear: La Farga and Lagerung in Girona, ahead of BYD in Catalonia, and Visenta and Perdiguero in Huesca, the only standalone projects named in Aragon. These are batteries built to do one thing: charge at midday and sell in the evening. Outside those two regions, the only standalone projects that name a maker are CATL's Orcoyen in Navarre and Saft's Tabiella in Asturias.

Other makers, almost all Chinese, lead batteries added to solar and wind farms: Tesla supplies none of them. Trina leads in Castilla-La Mancha with Tagus 2 in Toledo, Huawei in Andalusia, Envision in Extremadura, Sungrow in Castilla y León, CATL in Madrid and Canadian Solar in Aragon.

Tesla is the largest single maker overall: more than a quarter of all the battery capacity whose maker is named, almost twice as much as Huawei, although Huawei appears in more projects.

None is running yet: La Farga and Lagerung received preliminary approval in April and May 2026; Visenta and Perdiguero went to public consultation in August 2025.

What this means for solar owners

Solar farms selling on the market are unlikely to see midday prices recover soon. The projects already waiting to connect in Spain produce in the same hours as the plants running today, so each one that connects adds to the midday glut rather than easing it. Buyers have already repriced the plants: operating Spanish solar farms now sell for about half what they fetched in early 2024, according to nTeaser. Plants with fixed-price contracts or older regulated payments held their value better, and owners adding batteries of their own, almost all from Chinese makers such as Huawei and Trina, are buying back part of the evening price their farms can no longer reach.

Households have seen little of the fall. Spanish households on hourly tariffs see the midday glut most directly. On weekdays this year the market price in the hour from 12:00 averaged €28, against €140 in the hour from 20:00, yet the grid charge on the standard household tariff, in force since June 2021, is the same in both hours, and the tariff still counts 10:00 to 14:00 as peak. At home, noon power costs four and a half times its market price.

This is not restricted to Spain. In Germany, wholesale power costs less than half what it did in 2022, yet households pay more, according to Eurostat; France, where regulated tariffs were capped in 2022, tells the same story.

The batteries are coming. In the third quarter of 2026 alone, close to 2 GW of storage projects entered public consultation in Spain and about 1 GW received construction authorisation, almost all of it standalone, according to ESS News. As they connect, they will buy the midday power solar farms cannot sell and sell it in the evening, narrowing the gap. For solar owners, the question is no longer whether storage arrives, but whether they own it, or whether the batteries next door, many of them Tesla's, take the margin instead. Tesla sells the Megapacks and the Autobidder software that trades them; the evening margin itself goes to the companies that build and run the batteries.

Individual country results

Methodology

Prices are hourly day-ahead prices for each bidding zone, from the European power exchanges via Energy-Charts; Great Britain's are from Elexon's market index, in pounds, converted to euros at the European Central Bank's daily rate. Midday is 11:00 to 15:00 and evening 18:00 to 22:00, Central European Time. Zero-price hours are hours at or below €0. Generation is daily output by source from Energy-Charts, and for Great Britain from the National Energy System Operator's historic generation mix; solar's share is solar output divided by total generation. 2026 figures cover 1 January to 20 October. Household prices are Eurostat's (nrg_pc_204) for households using 2,500 to 4,999 kWh a year, all taxes included. Battery equipment comes from project filings in Spain's Boletín Oficial del Estado, which covers projects authorised by the national government but not those authorised by the regions; some filings allow an equivalent model. Battery revenues are from Clean Horizon's index as reported by ESS News, installed battery capacity in Spain from Red Eléctrica, and solar asset values from nTeaser. Battery capacity by maker is the installed capacity stated in each filing, and each project is assigned to its region from the province named in its filing. In the comparison of a solar farm with a Tesla battery, the solar farm earns the midday price and the battery the evening price minus the midday price in the same zone, before charging losses and grid fees; each country's zone is the one with its cheapest midday power. The storage pipeline for the third quarter of 2026 is from ESS News. Household grid charges are the network fees and policy charges of the standard household tariff, 2.0TD, for 2026 (CNMC Resolution of 18 December 2025; Order TED/1524/2025).