Residential photovoltaics in Belgium have changed dramatically over the past 5 years: more efficient panels, smarter inverters, revised regional grants. Here's how to size and choose an installation suited to your roof and consumption, in Wallonia, Brussels or Flanders.
Monocrystalline vs polycrystalline: which to choose?
Monocrystalline cells (efficiency 20-23%) are today the standard for residential installations in Belgium. They take up less space and maintain better performance in cloudy weather. Polycrystalline cells (efficiency 15-18%) are cheaper but require more surface area for the same power output.
In practice, for a roof with limited surface area, monocrystalline is the obvious choice. Half-cut and bifacial modules push efficiency up by 3 to 6% and have become the standard at major brands (Longi, JA Solar, Jinko).
String inverter, micro-inverter or power optimizer
The string inverter (SMA, Fronius, SolarEdge) remains the most widespread and least expensive solution. It centralises DC-AC conversion for the entire solar array. Drawback: partial shading on one panel penalises the whole string.
Micro-inverters (Enphase) process each panel independently: ideal for roofs with obstructions (chimney, skylight). Higher cost but per-panel monitoring. Power optimizers (SolarEdge P-series) combine the advantages of both: individual MPPT tracking with a central string inverter.
Sizing for a Belgian home
A Belgian home consumes an average of 3,500 to 4,500 kWh/year. With irradiance of approximately 900-950 kWh/kWp/year in Brussels/Antwerp, a 4-6 kWp installation (10 to 15 panels of 400 W) covers 60-80% of annual needs. With battery storage or a heat pump, this can exceed 90%.
Practical rule: allow 5-6 m² of roof area per kWp. Orientate south or south-west to maximise production. A tilt of 30-35° is optimal in Belgium, but even a 15° roof remains very profitable.
Grants and incentives 2026 in Belgium
In Wallonia, the green certificate (CER) rewards local production and there are investment grants from municipalities and intercommunals. In Flanders, the self-consumption grant has been replaced since 2021 by the digital bi-directional meter. In Brussels, Bruxelles Environnement offers RENOLUTION grants of up to 30% of installation cost.
In all regions, benefit from the reduced VAT rate of 6% for buildings over 10 years old (panels + inverter + installation). Always check with your municipality and distribution system operator (DSO) for local grants.
Frequently asked questions
How many solar panels for a family of 4?
For a consumption of 4,000 kWh/year, plan a 5 to 6 kWp installation, i.e. 12 to 15 panels of 400-420 Wp. With self-consumption, this covers about 70% of annual needs. With a home battery, you can reach 85-90%.
What is the difference between Longi LR5 and Hi-MO X6?
Both are high-quality monocrystalline PERC/HPBC modules. The Hi-MO X6 uses HPBC technology with slightly higher efficiency (22-23%) and better low-light performance. The LR5 is more affordable and very reliable. For residential use in Belgium, both are excellent choices.
Which inverter to choose for my photovoltaic installation?
For a roof without shading, a string inverter (Fronius Primo, SMA Sunny Boy or SolarEdge) is sufficient. With partial shading, prefer Enphase IQ8 micro-inverters or SolarEdge power optimizers. For large installations (>10 kWp), a three-phase inverter is recommended.
What grants can I get for solar panels in Belgium?
Wallonia: municipal/intercommunal grants + CER (green certificates). Flanders: digital net metering (no direct grant but financial compensation). Brussels: RENOLUTION grants up to 30% of cost. Everywhere: reduced VAT of 6% for buildings over 10 years. Check your regional energy agency and DSO for updated amounts.
What is the lifespan of solar panels?
Modern solar panels have a lifespan of <strong>25 to 30 years</strong>. Reputable manufacturers (Longi, JA Solar, SunPower) guarantee 80% of rated power after 25 years. The inverter has a shorter lifespan (10-15 years) and will likely need replacing once during the installation lifetime.
