Producing green electricity should, in theory, bring money to the public purse. In practice, France has sometimes seen the opposite, and the bill has been steep. A report from the Court of Auditors, released last spring, dissects the public support system for renewable energy, revealing a mechanism that is as costly as it is unpredictable. Between promises of an energy transition and budgeting overruns, this Rue Cambon institution presents a finding that deserves closer attention.
- From 2016 to 2024, public support for renewable energy has cost the French state 26.3 billion euros, averaging around 2.9 billion euros per year.
- Fixed twenty-year guaranteed purchase prices mean some producers continue to be paid even during periods of negative market prices, intensifying market dislocations.
- The Court of Auditors warns of risks of overpayment and a failure to adapt subsidies to falling production costs, while noting that the share of renewables in the power mix rose from 18% in 2016 to 27% in 2024.
- 26.3 billion euros: the hidden bill of France’s renewables
- Twenty-year guaranteed tariffs, regardless of market price
- When producing green electricity costs the grid money
- Overcompensation, too little competition: what the Court of Auditors points out
26.3 billion euros: the hidden bill of France’s renewables
The figure is staggering. According to the Court of Auditors, the contracts supporting the production of renewable electricity and biomethane cost the French state 26.3 billion euros between 2016 and 2024. When scaled to an annual basis, that still amounts to an average cost of 2.9 billion euros per year, a colossal sum that ultimately weighs on public finances. Yet this figure tells only part of the story.
Because behind this accumulated total lies a far more volatile reality. The Court indeed stresses that this expenditure can swing sharply from one year to the next, in step with the fluctuations in energy market prices. It is therefore not a fixed, predictable burden like a standard budget, but a line item that swings dangerously with the global energy context.
Twenty-year guaranteed tariffs, regardless of market price
To understand this volatility, you have to look under the hood of the scheme. The principle is simple, almost naive on paper: the state guarantees renewable energy producers a fixed purchase price for a period of roughly twenty years. If the market price falls below this guaranteed tariff, the state compensates the difference. But this mechanism can also work in the opposite direction when market prices soar, as evidenced by years with negative charges.
This mechanism has produced paradoxical situations. In 2022, and especially in 2023, the energy public-service charges turned negative, amounting to -3.12 billion euros for 2023 alone. In other words, during the energy-price surge triggered by the energy crisis, the state collected net revenues of 4.83 billion euros over that period. Yet the wind soon shifted: by 2024, the state was again paying out 3.9 billion euros, and the Court of Auditors anticipates a bill of 7.3 billion euros for 2025. A figure enough to make any public-finance manager dizzy.
When producing green electricity costs the grid money
That is where the system reveals its absurdity: during episodes of negative prices on the electricity market. These moments occur when production exceeds demand on the grid. In a conventional market, such an excess would prompt producers to scale back. But with a twenty-year guaranteed tariff, the equation changes entirely: the producer continues to be paid at the fixed rate, regardless of what is actually happening on the grid.
As a result, some producers have little economic incentive to shut down their plants when prices fall below zero, since their remuneration remains secured by the compensation mechanism. This setup mechanically contributes to worsening episodes of negative prices, a phenomenon some sector observers prefer to label a grid-flexibility problem rather than an intrinsic fault of renewables themselves. Still, the support scheme, as designed, does nothing to correct this drift.
Overcompensation, too little competition: what the Court of Auditors points out
Beyond the question of negative prices, the Court of Auditors highlights structural weaknesses in the very design of the support schemes. It points to risks of overpayment and windfall effects, tied, in its view, to an insufficient understanding of the real economics of the relevant sectors. In other words, public authorities may have at times set tariffs too generous, lacking a sufficiently precise assessment of production costs.
The report also underscores a glaring lack of adaptation to market evolutions: subsidies have often been kept at high levels even as the production costs of renewable energy fell significantly over the years. A mismatch that could have fostered insufficient competition in some bidding rounds, allowing high tariffs to endure without solid economic justification. Unapologetically, the Court of Auditors calls these schemes “costly, unfair, and unpredictable,” a phrase that aptly sums up the scale of the dysfunctions identified.
Yet it would be unfair to reduce this report to a simple indictment. Renewable electricity production has indeed progressed spectacularly, rising from 100 TWh in 2016 (18% of national production) to 150 TWh in 2024, now accounting for 27% of France’s electricity production. Public support has thus fulfilled part of its initial mission, namely speeding up the deployment of green sectors.
The cost-effectiveness equation, however, now deserves reconsideration. Between a regime that has nearly tripled the share of renewables in the French electricity mix and billions of euros spent with sometimes no real counterpart for the grid, there is still substantial room for improvement. At a time when carbon neutrality remains an explicit objective for 2050, the question is no longer whether to support renewables, but how to do so without repeating the same budgetary missteps.
