A homeowner in Germany with ten solar panels, totaling 4.5 kWc, reported that during a July noon, the house consumed only 300 W while the panels produced 3,500 W. The excess energy flowed into a solar battery, and the homeowner even modified the electric car's charging system to absorb surplus energy. This scenario, once a personal challenge for homeowners, has now become public policy in Germany. A bill proposed by the Minister of Economy Katherina Reiche passed the cabinet on July 29 and had its first reading in the Bundestag on September 24, with an intended entry into force on January 1, 2027. For new small and medium-sized roof installations, the injection at the connection point will be permanently capped at 50% of the installed power, with or without a smart meter. A 10 kW installation, the average size in Germany, will therefore never be able to send more than 5 kW to the grid. Self-consumption and storage are not affected, and the panels still produce at full capacity. The guaranteed buyback rate for 20 years is being replaced with a transitional premium of 36 months, starting at 5.20 cents per kWh, followed by a mandatory transition to direct sale on the market. Balcony kits up to 2 kW are exempt from this, as their inverters are already limited to 800 W. Without a battery, up to 16% of production is lost. The capping is not an absolute novelty in Germany. A 70% rule existed until 2022, then a 60% limit was reintroduced in February 2025 for installations without a smart meter. The difference this time is that you can no longer get around it by installing a smart meter: the cut is definitive. According to calculations by the HTW Berlin, a 10 kW installation with full injection would lose between 12 and 16% of its annual production. With a 10 kWh battery intelligently controlled, the loss drops to around 1%. The official discourse speaks of smoothing midday peaks, when the wholesale price drops to zero or negative. However, with a buyback rate of 7.7 cents and electricity billed at 30 to 40 cents per unit, a German has already an interest in consuming their electricity rather than selling it. This capping makes a battery mandatory to avoid any loss. In France, there is no injection capping, but there are similar economic pressures. A decree of June 1, 2026, has reduced the buyback rate of the surplus to 1.1 cents per kWh for all installations up to 100 kWc and abolished the self-consumption premium. At the beginning of 2025, the same kWh was still worth 12.69 cents, then 4 cents after March 2025. Facing a regulated rate of 20 cents, selling your electricity earns 18 times less than saving it. The result is the same as in Germany, without going through the law or the inverter. In both countries, the good customer is the household with heat pump, electric car, and battery, which absorbs its production during the day. The bad customer, the one who has covered their entire south-facing roof, counting on resale, ends up with oversized panels. Unless, of course, they still benefit from an old resale contract. The German method is brutal, but it has the merit of being readable: the rule is written, numerical, and the installer can size accordingly. In France, the same effect is achieved with a low buyback rate. As a result, on both sides of the Rhine, the battery has become necessary, and the roof filled to the brim no longer makes sense.