For years, installing solar panels meant making “your meter spin backwards”: every kilowatt-hour injected cancelled out a kilowatt-hour consumed in the evening, at the same price. That mechanism has gone. Today, the grid buys back your surplus at a very low rate, around €0.05 per kilowatt-hour, while you buy it back in the evening at nearly €0.35. The consequence is crystal clear: the profitability of your installation no longer depends on what you produce, but on what you consume yourself, at the moment you produce it. This is self-consumption — and here’s how to push it to the maximum.
Why self-consumption decides everything
The self-consumption rate is the share of your solar production that you use directly at home, without going through the grid. A Belgian household equipped with solar panels and no control whatsoever spontaneously sits around 30 to 35%. The rest goes onto the grid, bought back for a pittance.
The reasoning fits in one sentence: a kilowatt-hour consumed under your panels saves you €0.35, whereas the same kilowatt-hour injected only earns you €0.05. The gap is sevenfold. Each kilowatt-hour you manage to consume instead of injecting is therefore worth far more than the one you resell.
That’s the gap, per kilowatt-hour, between self-consuming (saving ~€0.35) and injecting (selling at ~€0.05). The whole challenge is to shift as many kilowatt-hours as possible from the second case to the first.
Good news: raising this rate doesn’t necessarily require investment. The first levers are free — they’re simply changes of habit. The next ones are about equipment, and become worthwhile as you want to go further.
Lever 1 — Shift your usage to the middle of the day
This is the most profitable action, because it costs nothing. Your production peaks between 11am and 4pm; that’s exactly when you should run the power-hungry appliances.
- Washing machine and tumble dryer: set the delayed start for the middle of the day rather than the evening.
- Dishwasher: run it after lunch, not after dinner.
- Electric water heater: reprogram its heating window to solar hours instead of overnight.
Each of these appliances consumes several kilowatt-hours per cycle. Shifting them to the production peak means that much free electricity rather than electricity bought at full price. On its own, this discipline often pushes the self-consumption rate from 35% to nearly 50%.
Lever 2 — Control and automate
Shifting your appliances by hand requires consistency. Home automation does the work for you: a smart plug triggers the water heater or the filtration pump as soon as production exceeds a threshold; an energy manager reads your surplus in real time and arbitrates usage automatically.
The benefit is twofold: you no longer miss any sunny production window, and you keep a clear view of what is being self-consumed. Well set up, control turns good intentions into an invisible routine.
“The best kilowatt-hour is not the one you resell, nor even the one you store: it’s the one you consume the moment it’s produced.
Lever 3 — The thermodynamic water heater, a thermal battery
Domestic hot water is one of the biggest electricity items in a home. A thermodynamic water heater produces it with an integrated heat pump, three to four times more efficient than a conventional element. Set to heat in the middle of the day, it absorbs a large share of your solar surplus.
It is, in practice, a thermal battery: you store the energy as heat, for far less than an electric battery. For a household that uses a lot of hot water, it’s one of the best gain/investment ratios on the table.
Lever 4 — Charge your electric vehicle during the day
An electric car gulps 10 to 15 kWh for a typical daily charge. Plugged in at night, it draws everything from the grid at full price. Plugged in during the day, or controlled by a smart charger that only charges on the solar surplus, it becomes a tremendous self-consumption reservoir.
It’s even one of the few uses able to absorb a large midday surplus, where a home battery would already be full. If you drive electric, it’s a first-rate lever.
Lever 5 — The home battery
This is the most powerful lever. A battery stores the surplus produced during the day to deliver it in the evening and at night, exactly when you need it. It can take a self-consumption rate from 35% to 70%, sometimes more depending on your profile.
It can’t be improvised, though: its cost remains significant, and its value depends on your real surplus, your habits and the sizing of your panels. It’s a calculation to make after pulling the free levers, not before.
Capacity, self-consumption gain and real cost: everything you need to decide whether the battery is worthwhile in your specific case.
Discover battery storage →Lever 6 — Size the installation well
The more oversized your panels are relative to your consumption, the more your surplus goes to the grid at a low price. Conversely, an installation calibrated as tightly as possible, aligned with your consumption profile, naturally self-consumes a larger share of its production.
Good sizing isn’t just about the number of panels: orientation matters too. An east-west roof spreads production across the whole day — a peak in the morning, a peak in the evening — and often matches a household’s usage better than a due-south roof, which concentrates everything at midday.
Let’s recap the nine levers
- Shift your usage (washing machine, dishwasher, water heater) to the middle of the day — free.
- Control and automate via smart plugs and an energy manager.
- Thermodynamic water heater — store the surplus as hot water.
- Charge the electric vehicle during the day, on the solar surplus.
- Home battery — the most powerful lever: from 35% to 70%.
- Size panels and orientation well to your consumption profile.
Where to start in practice
The logical order is simple: first you bank the free gains, then you invest. Concretely, start by reprogramming your appliances and your water heater to solar hours — it’s immediate and costs nothing. Then add control to automate everything. Then, depending on your profile, consider the thermodynamic water heater, solar charging of the vehicle, and finally the battery.
Before investing in storage, measure your real situation. Our profitability simulator estimates your current self-consumption rate and the expected gain of each lever, taking into account the prosumer tariff applied to your connection. You’ll then know where your most profitable kilowatt-hours are — and in what order to capture them.
Self-consumption rate, annual savings and payback time: a figures-based calculation, tailored to your roof and your consumption habits.
Estimate my savings →Maximising your self-consumption isn’t a matter of cutting-edge technology: it’s first and foremost a question of common sense and timing. Consume when the sun produces, automate what can be automated, store the rest when the calculation justifies it — and your panels will really work for you.
Guide verified in May 2026 · updated every year