The most common question before going solar: 'how long until it pays for itself?'. In Luxembourg, the answer mainly depends on the net cost after the Klimabonus grant, the share of electricity you consume yourself, and the price of the electricity you avoid buying.
Here is how to read a system's returns, with an indicative worked example and the levers that really make the difference. All amounts are orders of magnitude, to confirm with a quote and a simulation of your roof.
How long until it pays for itself?
The payback period is calculated on the net cost, that is the turnkey price minus the Klimabonus grant. In Luxembourg, this period is generally around 8 to 12 years depending on system size, roof orientation and, above all, your self-consumption rate.
Because panels last 25 to 30 years and keep producing well beyond payback, the remaining years are a net gain. In practice: once the system is paid off (around year 8-12), the electricity you produce and consume becomes almost pure savings for another 13 to 17 years.
Payback depends on real variables (consumption, electricity price, weather): these figures are indicative and not guaranteed.
Worked example (6 kWp)
Item
Amount
Turnkey price
~€11,800
Klimabonus grant
−€5,700
Amount left to pay
~€6,100
Savings / year
~€800
Pays for itself in
~8 years
Net gain over 25 years
~€14,000
Indicative. Assumes ~40 % self-consumption, to adapt to your profile and confirm by quote.
What improves the returns
High self-consumption
Every kWh used on site avoids a grid purchase (~€0.20/kWh), far more profitable than exporting it. Shifting usage (washing machine, car, water heater) to daytime raises this rate.
Good orientation & tilt
A south-facing (or east-west) roof with a good tilt maximizes annual output — and therefore savings — at no extra cost.
The Klimabonus grant
It directly reduces the net cost and shortens payback. It is the most powerful public lever in Luxembourg.
A controlled price
Comparing quotes avoids overpaying, which would lengthen payback. The right hardware at the right price beats the 'cheapest at any cost'.
With or without a battery?
A battery stores the daytime surplus to use in the evening. It raises self-consumption (often from ~40 % to 60-70 %), and therefore annual savings. But it adds a significant cost that lengthens the payback.
Without a battery, payback is around 8-12 years. With a battery, it stretches closer to 10-14 years: you consume more of your own energy, but the upfront investment is higher. The choice depends on your consumption profile (evening presence, electric car) and your goal — pure returns or autonomy.
As things stand, without an exceptional feed-in tariff, a battery is justified mainly by autonomy and comfort rather than returns alone. It is a trade-off to make according to your priorities.
Frequently asked questions
Is solar really profitable in Luxembourg?
Yes, in most cases, thanks to the Klimabonus grant that strongly reduces the net cost and the price of the electricity avoided (~€0.20/kWh). Payback is generally around 8 to 12 years, for panels that last 25 to 30 years. These are orders of magnitude, not a guarantee.
What affects payback the most?
Your self-consumption rate and the net cost after the grant. The more of your own electricity you consume instead of exporting it, the less you buy from the grid, and the faster the payback.
What happens after payback?
Once the system is paid off, the electricity you produce and consume becomes almost pure savings for the rest of the panels' lifespan (often another 13 to 17 years), giving a net gain that can exceed €14,000 over 25 years for a 6 kWp system.
Does a battery improve the returns?
Not directly. It raises self-consumption and therefore annual savings, but its cost lengthens the payback (closer to 10-14 years). It is justified mainly by autonomy and comfort.
Is your roof right for solar?
Estimate your roof's output, savings and grant for free — then get a quote to confirm your real payback.
General information for educational purposes. Amounts are indicative and not guaranteed, depending on your consumption, the electricity price and your roof. To confirm with a simulation and a professional quote.