Generating electricity can now actually cost money. Instances of negative prices are becoming increasingly common on the Germany-Luxembourg electricity market, putting pressure on the profitability of solar power producers. These occur when supply – driven in particular by renewable energy sources – exceeds demand. In such situations, the wholesale price falls below zero and generators are no longer paid for the electricity they feed into the grid; some even have to pay to get rid of it. It is against this backdrop that the Ministry of the Economy launched two new photovoltaic tenders on Wednesday 5 August, totalling 110 MW, with one major new feature: projects incorporating batteries will now be given preference during the selection process.
The third tender for agrivoltaic power stations covers 75 MW, whilst the eighth tender for large-scale installations on rooftops, façades, car park canopies and other impervious surfaces accounts for 35 MW. As in previous rounds, the successful projects will benefit from a 15-year feed-in tariff contract. However, this year, storage capacity will be taken into account when ranking bids, in order to encourage projects capable of shifting their generation outside periods when prices turn negative.
This development is a direct response to a trend that is gathering pace. In a reply to a parliamentary question from MPs 
Acceleration in the number of hours with negative prices
The figures illustrate this acceleration. After 139 hours in 2021 and 69 hours in 2022, the number of hours with negative prices rose to 301 in 2023, then to 457 in 2024, before reaching a record 573 hours in 2025. Since the market switched to quarter-hourly pricing, 1,178-quarter hours of negative prices have already been recorded between 1is 1 January and 30 June 2026.
For operators of solar power stations, these episodes have very real consequences. European guidelines prohibit the payment of production subsidies when market prices are negative. For the most recent installations benefiting from a market premium, payments will be suspended as soon as prices remain negative for two consecutive hours in 2026, before this threshold is reduced to one hour from 2027 onwards.
The government emphasises, however, that these periods are not lost. The hours during which the premium is not paid will be offset by an equivalent extension of the duration of the market premium contract, which is set at fifteen years. However, it is not currently possible to quantify the number of hours involved, as this depends on the production profile of each plant.
Batteries are a game-changer
In this context, batteries are a game-changer. By enabling electricity to be stored when the market is saturated so that it can be sold at a later date, they reduce exposure to periods of negative prices. The Ministry also states that it is continuing its work on flexibility solutions, notably storage, active demand management and the development of market mechanisms.
Lex Delles, however, dismisses the idea that strengthening interconnections with neighbouring countries could solve the problem. Luxembourg shares the same price zone as Germany, and episodes of negative prices result mainly from an imbalance between abundant renewable generation and insufficient demand across this vast market area. According to the minister, increasing cross-border transmission capacity would therefore have a “very limited, if any” impact on these episodes.
Beyond the 110 MW put out to tender, these new calls for tenders illustrate a fundamental shift in the electricity market. Installing more solar panels is no longer enough. The value of a power station now also depends on its ability to store its output to avoid times when generating electricity… no longer yields any profit.
