Solar panels: profitability and surplus

Are solar panels still worth it? In Wallonia, the answer depends less on the price of the panels than on what becomes of the electricity you do not consume. Consumed at home as it is produced, a kilowatt-hour is worth about ten times the same kilowatt-hour injected into the grid: 36.94 c€ against 3.5 c€, at average mid-2026 prices. With no compensation for systems commissioned since 1 January 2024, and no meaningful public support, profitability depends on what you do with your production, as “Solar panels 2026: still worth it in Wallonia?” sets out. Before asking for quotes, look at your situation:

• No panels yet? Size for your consumption, not for your roof: every kilowatt-hour produced beyond what you can absorb leaves at the injection tariff.
• House empty during the day? The problem is neither production nor hardware, but the calendar and the wiring. Before thinking of a battery, look at your hot-water tank: “Solar panels: nobody home during the day” shows it is the best surplus absorber in a home, but often wired to heat at night.
• Renting? A portable photovoltaic kit plugged into a socket is now legal in Belgium and moves house with you; declaring it is compulsory and gets you a free communicating meter, which unlocks energy sharing. “Renting: the no-roof guide to solar” explains why to look at the length of your lease before the hardware.

Once the panels are up, check your metering regime first. A system commissioned before 1 January 2024 keeps compensation until 31 December 2030: your surplus is already valued at full retail price, up to the level of your annual consumption, and usually you are better off buying nothing, unless the system is oversized. For everyone else, “Solar surplus: the 5 options compared” shows that the answer is a stack, not a choice: shift the loads you already have, control the hot-water tank, then the car’s charging if it is at home during the day, share the remainder, export what is left, and consider a battery last.

The battery is effective but expensive: its payback is roughly its service life. It can be combined with energy sharing, but the gains do not add up: the better your sharing price, the weaker the case for a battery, as “Home battery: the price and the alternative” calculates.

Energy sharing asks for neither investment nor presence: it borrows, quarter-hour by quarter-hour, the consumption of other participants, and it is open to tenants, because it follows the meter, not the title deed. Its gain remains modest: it only replaces the energy component, network charges and levies remain due, and supplier fees can swallow it. A system predating 2024 must also give up compensation to take part. In Wallonia, sharing runs through the same building or an energy community; peer-to-peer between neighbours remains inoperative there, and existing operations are still rare.

The guides below follow these two stages: deciding to install, then making the most of your surplus.