A few years ago, a solar installation was often used to sell all its output at a guaranteed tariff. That model has gone. Today, a successful installation is one that lets the household use as much of its own electricity as possible, at the right time.
Why selling is no longer enough
The surplus buy-back tariff fell to around 4 cents per kWh in 2025. During some very sunny hours, the market price of electricity even becomes zero or negative: producing more at those times earns nothing. Each kWh used at home, on the other hand, avoids buying one at grid price. That is where most of the economic value lies.
1. Use electricity when the panels produce
The first step is not a battery, but shifting usage. A home energy management system (HEMS) automatically starts the water heater, heat pump, vehicle charging or pool pump when output is available. Across about 200 projects analysed by software publisher Revolt.eco, adding a HEMS raised the self-consumption rate by 18 points on average.
2. Store, if your profile suits it
A physical battery lets you use in the evening the electricity produced during the day. Its share of projects rose sharply in 2025, but it is not universal: its value depends on your schedule, the season, its cost and its capacity. An oversized battery can harm the project’s return; combined with energy management, it can often be smaller.
A virtual battery is another option: not equipment, but a contract that credits injected surplus so you can recover it later. Terms (subscription, fees, duration) vary between offers and are worth comparing.
3. Size for tomorrow’s uses
A heat pump, an electric vehicle or a thermodynamic water heater can noticeably increase your consumption. If you are planning them, it helps to include them in the study, so you do not install a capacity that soon becomes too small.
4. Improve an existing installation
Many installations were designed without storage or energy management. Adding a HEMS, a battery, an EV charger or a few panels can improve their value. A study of actual production and consumption shows what is worthwhile.
What to check in a proposal
- A production and self-consumption estimate based on your actual consumption, not an average
- A justification for each item proposed (energy management, battery, charger)
- The qualifications (QualiPV, RGE) and ten-year insurance of the installing company
- The formalities included: town-hall declaration, grid connection, compliance certificate
- No guaranteed savings: output depends on actual sunshine and your usage
Figures quoted: “Le photovoltaïque en 2030” guide, Revolt.eco, 2026. Buy-back and tax conditions change: they are checked at the time of your study.
Frequently asked questions
Is a battery essential?
No. For many households, managing usage already brings most of the gain. A battery is justified by your consumption times and its cost.
Is solar still worthwhile?
Yes, when designed for self-consumption: equipment costs have fallen sharply and each kWh used on site avoids a grid purchase. The actual value depends on your roof and your consumption.