One afternoon in July, a homeowner used a smartphone app to carefully adjust the charging intensity of their electric car, reducing it by ampere (A) increments. Their rooftop was equipped with ten 450 W solar panels, producing just over 3 kW of power. The goal was to avoid sending any electricity back to the grid. At 10 A, the car consumed 2.3 kW, and the electricity meter reversed as soon as a cloud passed overhead. At 6 A, the car used 1.4 kW, allowing the fridge to run alongside. However, the process consumed much of the afternoon, which the user noted doesn’t align with the idea of true energy autonomy. A new government regulation, published in the Official Journal on June 5, changed the financial incentives for solar energy. The purchase price of surplus electricity was reduced to 1.1 cents per kWh HT for new installations, down from 4 cents previously. The self-consumption bonus was also eliminated. This new rate applies only to installations where the connection request was submitted after June 5. Existing systems, installed before this date, retain the higher rate of around 4 cents per kWh, guaranteed for 20 years. Meanwhile, the regulated base electricity rate is about 19 cents TTC, making a solar-generated kWh consumed at home 18 times more valuable than one sold to the grid. The government’s message is clear: keep your electricity for yourself. Electric vehicles have specific power requirements for charging. Most can only accept alternating current (AC) down to 6 A, which is 1,380 W, and some, like the Renault Zoe, require at least 10 A (2,300 W) to begin charging. Energy losses also play a role—some vehicles, like the MG4, lose between 8 and 15% of the energy during the charging process. At this rate, a 55 kWh battery would take over 24 hours to fully charge using only solar power, and the sun would have set by then. Instead, many users aim for a partial charge—around 5 to 8 kWh, enough for 30 to 50 km of driving—on a sunny day. The number of solar panels needed depends on the amount of surplus power available at noon, after household appliances like the fridge and ventilation system have drawn their share of power. To charge an electric car using only solar power, you generally need at least four 450 to 500 W panels, along with a buffer battery to maintain a stable power supply. Without the battery, the car may stop charging if cloud cover reduces the solar output below 1,380 W. Starting with eight panels, you can charge the car without a buffer battery during the better part of the summer. Ten panels allow charging at higher amperage levels, but only under clear skies and between March and October. The key challenge is matching the car’s power needs with the actual solar output, which is often lower than the peak capacity listed on the panels due to weather and orientation. For those aiming to achieve energy autonomy, the next step after installing solar panels is deciding whether to add a home battery. These can cost between 1,500 and 3,000 euros for 5 kWh of storage, but they typically cycle only once per day, resulting in limited annual savings—around 300 euros at the current electricity rate. In contrast, an electric car already has a built-in battery, and each solar kWh that charges it replaces a kWh purchased from the grid, which can cost 40 to 60 cents. The cost of achieving this is minimal, limited to a controllable charger, which can range from 150 to 800 euros depending on the desired level of control. For those seeking a fully automated system, surplus charging setups use real-time measurements and smart controls to ensure no electricity is injected into the grid. These systems can be assembled using dedicated wallboxes or open-source software like evcc, which runs on a Raspberry Pi or similar device.