How does solar pre-financing work in Luxembourg? Complete guide to the Klimabonus third-party payment 2026
Since 4 January 2026, Luxembourg has introduced a third-party payment system for photovoltaic installations: the Klimabonus grant is deducted directly from your invoice by the installer, with no need to advance State aid. You only pay a deposit of maximum 30% of the total price including VAT, then only the net balance after the grant is deducted. The State reimburses the installer within 30 days. This page explains the mechanism, eligibility conditions, step-by-step procedure and pitfalls to absolutely avoid to benefit from this scheme safely.
Calculate your net cost with pre-financing. Our simulator uses the new 2026 degressive Klimabonus formula. Get your net amount in 2 minutes.
Simulate my pre-financing →What is photovoltaic pre-financing in Luxembourg?
Photovoltaic pre-financing — also known as the solar third-party payment — is a legal mechanism that came into force on 4 January 2026 in the Grand Duchy, introduced by bill 8463. The principle is simple: rather than paying the full cost of your installation and then waiting for the State to reimburse the Klimabonus grant, your installer now advances the grant on your behalf. The grant is deducted directly from your final invoice, and the State reimburses the installer.
Ministers Lex Delles (Economy) and Serge Wilmes (Environment) presented this mechanism as the flagship measure to remove the main barrier to solar adoption in Luxembourg: the cash advance, which could represent tens of thousands of euros for homeowners before being reimbursed — sometimes months later.
The government has also announced its intention to progressively extend this scheme to other components of the Klimabonus Wunnen programme (heat pumps, insulation, etc.), but in 2026, it applies exclusively to photovoltaic installations, with or without a domestic battery coupled to the initial installation.
This guide covers the pre-financing mechanism exclusively. For full details on Klimabonus amounts, reduced VAT, municipal grants and Enoprimes, see our complete guide to solar panel grants in Luxembourg.
Before / after: what changed on 4 January 2026
To understand the scale of the change, here is a direct comparison between the old Klimabonus system and the new pre-financing. Both routes still legally coexist, but pre-financing is by far the most advantageous solution for homeowners wishing to minimise their financial exposure.
| Criterion | Old scheme (classic route) | New pre-financing (since 4 Jan. 2026) |
|---|---|---|
| Who advances the grant? | The homeowner (advances 100%) | The installer (you advance nothing) |
| Maximum deposit | 50–100% of total price inc. VAT | 30% of total price inc. VAT — legal cap |
| Who submits the application? | The homeowner (via Environmental Administration) | The installer (via MyGuichet.lu, on your behalf) |
| Reimbursement delay | Variable, could exceed several months | Maximum 30 days (15 d. decision + 15 d. payment) |
| Grant calculation basis | 50% of eligible costs (vague notion) | Degressive formula on installed kWp (transparent) |
| Max. panels grant | Approx. €1,250/kWp (capped) | Up to €10,000 (reached at 15 kWp) |
| Domestic battery | Included in eligible costs | Separate grant, up to €2,250 (max at 9 kWh) |
| Administrative management | Homeowner’s responsibility | Fully managed by the installer |
| Digital procedure | Partial | 100% via MyGuichet.lu |
Whether you choose pre-financing or the classic route, your Klimabonus grant amount remains strictly identical. Pre-financing does not change the subsidy calculation — it only changes the timing and recipient of payment, and who handles the admin.
How the third-party payment works in practice
The pre-financing mechanism is based on a three-actor chain: you (the beneficiary), your registered installer, and the Ministry of Economy. Here is the concrete financial flow:
1. At contract signing: You sign the offer and the co-signed mandate with the installer, authorising them to submit the pre-financing application on your behalf. You pay a deposit of maximum 30% of the total price including VAT. Beyond this legal cap, the installer is in breach.
2. After installation: The installer carries out the work, submits the end-of-work declaration (EWD) to the network operator (Creos or Enovos), then issues the final invoice. On this invoice, the Klimabonus grant amount is visibly deducted from the total price inc. VAT. You can see exactly what the State covers.
3. Application submission: The installer submits the pre-financing application via MyGuichet.lu on behalf of the beneficiary, with all required supporting documents. This is entirely their responsibility.
4. Decision and reimbursement: The Ministry of Economy has 15 working days to decide. After this period without a response, the silence equals agreement principle applies automatically. Reimbursement to the installer occurs within 15 days of the decision — a complete cycle of approximately 30 calendar days, enshrined in law.
5. Your final balance: You pay the installer only the remaining balance: total price inc. VAT − deposit already paid − deducted Klimabonus grant. In most residential cases, this balance represents 30% to 60% of the initial gross price.
Pre-financing is not possible for a storage battery added alone to an already existing photovoltaic installation. If you already have solar panels and wish only to add a battery, you must go through the classic post-financing procedure with the Environmental Administration.
The 5 key steps of your project with pre-financing
Simulate your grant and choose a registered installer
Use the official Klima-Agence calculator (aides.klima-agence.lu) to find out your exact Klimabonus based on your installation’s kWp power. Then verify that your installer is listed in the approved installers register on guichet.public.lu — without this registration, pre-financing is impossible.
Sign the offer and the pre-financing mandate
You and your installer co-sign a client agreement (official document on MyGuichet.lu) confirming your choice of pre-financing, the order date, and the offer’s total price inc. VAT. Your deposit is capped at 30% of the total price inc. VAT — requiring more is a legal violation.
Installation and end-of-work declaration
Your installer carries out the panel (and battery) installation, then transmits the end-of-work declaration (EWD) to the network operator — Creos for most of Luxembourg’s territory. Without this prior declaration, no pre-financing application can be submitted.
Net invoicing and application submission on MyGuichet.lu
The installer issues the final invoice inc. VAT with the Klimabonus grant visibly deducted, then submits the pre-financing application on MyGuichet.lu with all supporting documents. You have no administrative steps at this stage.
Decision, reimbursement and settlement of your final balance
The Ministry of Economy decides within 15 working days (silence equals agreement thereafter). Reimbursement to the installer occurs within the following 15 days. You then pay your final balance: total price inc. VAT − deposit paid − Klimabonus. Your installation is operational and fully subsidised without ever advancing State aid.
Pre-financing eligibility conditions
Pre-financing is open to any individual or legal entity owning or holding real property rights on a residential building in Luxembourg, including co-ownerships via mandated property manager. Businesses subject to an artisanal, commercial or professional establishment permit are explicitly excluded.
| Condition | Detail |
|---|---|
| Minimum power | At least 2 kWp |
| Maximum power | 30 kWp for residential (beyond this, different regime) |
| Operating mode | Self-consumption only — no guaranteed feed-in tariff contract |
| Installer | Must be registered in the official pre-financing register |
| Eligible order period | Between 1 October 2024 and 31 December 2029 |
| Legal maximum deposit | Cannot exceed 30% of the total price inc. VAT of the signed offer |
| Mandatory documents | Co-signed client agreement + EWD sent to network operator + final invoice |
| Standalone battery addition | Not eligible for pre-financing — classic route mandatory |
| Leasing | Incompatible with pre-financing — classic route available for this case |
Installations benefiting from the guaranteed feed-in tariff (€0.1374/kWh for 15 years) are not eligible for the new Klimabonus or pre-financing. These two schemes are incompatible. To benefit from pre-financing, your installation must operate in self-consumption mode with a formal waiver of the guaranteed feed-in tariff.
The pre-financing approved installers register
The register of installers approved for the pre-financing procedure is the central element of the scheme. It is published and maintained by the Ministry of Economy and can be consulted at any time on guichet.public.lu. Its existence responds to a logic of quality and fraud prevention.
Conditions for registration include being established in Luxembourg or an EU member state, holding a valid establishment permit, and submitting a registration request via MyGuichet.lu with eIDAS authentication.
If an installer is removed from the register, all applications submitted before the removal decision are automatically refused — including for affected clients. Always check your installer’s status before signing anything.
Visit guichet.public.lu/fr/citoyens/outils/registre-installateurs.html and search by installer name or company number. This register is regularly updated by the Ministry of Economy.
Official deadlines and legal guarantees
One of the major contributions of pre-financing is the contractualisation of deadlines in the law. Here are the official Ministry of Economy commitments, enshrined in bill 8463:
| Stage | Legal deadline | Guarantee |
|---|---|---|
| Decision on pre-financing application | 15 working days after receipt of complete file | Silence equals agreement — automatic favourable decision |
| Payment to installer | 15 days after agreement decision | Legally guaranteed payment |
| Total State → installer cycle | ≈ 30 calendar days | Governed by law (PL 8463) |
The « silence equals agreement » principle protects installers against administrative delays that could paralyse cash flow. As a client, the law guarantees that the grant amount deducted on your invoice is final from the moment the mandate is signed and the installation technically validated.
Simulation: how much will you really pay with pre-financing?
To concretely illustrate the impact of pre-financing, here are four representative residential project examples. Klimabonus amounts are calculated according to the official degressive formula in force since 4 January 2026.
| Scenario | Estimated price inc. VAT | Max. deposit (30%) | Klimabonus deducted | Client final balance | Grant coverage |
|---|---|---|---|---|---|
| House — 3 kWp | ~€7,000 | ~€2,100 | ~€3,750 | ~€3,250 | ~54% |
| House — 5 kWp (family of 4) | ~€11,500 | ~€3,450 | ~€6,250 | ~€5,250 | ~54% |
| House — 8 kWp + 8 kWh battery | ~€22,000 | ~€6,600 | ~€11,170 | ~€10,830 | ~51% |
| House — 15 kWp (max subsidised) | ~€30,000 | ~€9,000 | ~€10,000 | ~€20,000 | ~33% |
Indicative amounts based on the 2026 degressive Klimabonus formula. Use the aides.klima-agence.lu simulator for a precise personalised calculation.
With pre-financing, your initial outlay (the 30% deposit) ranges from €2,100 to €9,000 depending on system size — instead of advancing €7,000 to €30,000 before waiting for reimbursement. This is precisely the cash flow problem the mechanism was designed to solve.
Pre-financing or classic route — which to choose?
Both routes coexist legally and entitle you to the same grant amount.
| Your situation | Recommended option | Why |
|---|---|---|
| You want to minimise cash outlay | Pre-financing | Deposit limited to 30% — no advance on the grant |
| You prefer to delegate all admin | Pre-financing | Installer manages 100% of procedures on your behalf |
| Your installer is not registered | Classic route | Pre-financing is impossible without register entry |
| You are adding a battery to an existing installation | Classic route | Pre-financing explicitly excluded for this case |
| Your installation is on a leasing contract | Classic route | Leasing is incompatible with pre-financing |
| Order between Oct. 2024 and March 2026 (transitional period) | Compare both | Old scheme (50% of costs) may be more advantageous for some sizes |
| You benefit from the guaranteed Enovos feed-in tariff | Neither (incompatible schemes) | New Klimabonus excluded with guaranteed feed-in contract |
Transitional period: orders from October 2024 to March 2026
A retroactive transitional phase was provided by law for installations ordered between 1 October 2024 and 4 March 2026. During this period, you can freely choose between:
| Option A | Old scheme: 50% of eligible costs, maximum approximately €1,250/kWp. No pre-financing. Final invoice must be issued by 31 December 2026. May be more advantageous for large installations (≥ 15–20 kWp) where the old cost-based calculation can exceed €10,000. |
| Option B | New scheme: degressive formula per kWp, cap at €10,000. Pre-financing possible if installer is registered. Conditions: final invoice not yet issued and deposit not exceeding 30%. Generally more advantageous for 2–12 kWp installations. |
The two schemes are strictly non-combinable: you choose one or the other. Ask your installer to simulate both options before deciding — the optimal choice depends heavily on your installation’s power.
5 pitfalls to absolutely avoid with pre-financing
Pitfall 1: paying a deposit above 30% of the total price inc. VAT
If your installer requests 40, 50 or 60% upfront, they are violating legal pre-financing conditions — potentially invalidating your application. Solution: insist that your contract explicitly states the deposit does not exceed 30% of the total price inc. VAT.
Pitfall 2: choosing an installer without checking their register entry
A good website, local reputation or years of experience do not replace a check in the official register. A non-registered installer simply cannot submit the pre-financing application. Solution: systematically verify on guichet.public.lu before signing anything.
Pitfall 3: signing the mandate without reading the client agreement
The mandate authorises the installer to act on your behalf. Verify it mentions the order date, the offer’s total price and your explicit choice of pre-financing. An incomplete mandate leads to rejection. Solution: read every line before signing — ask your installer to explain anything unclear.
Pitfall 4: confusing pre-financing and leasing
A leased photovoltaic installation cannot benefit from pre-financing — the two mechanisms are incompatible. Solution: clarify upfront with your installer whether your contract is a direct purchase or a lease.
Pitfall 5: believing pre-financing is possible for a standalone battery addition
If you already have solar panels and wish only to add a battery, pre-financing is impossible. Solution: if you plan both panels and a battery, include both in the same initial order to benefit from pre-financing on the full amount.
Ready to launch your project with pre-financing?
Simulate your 2026 Klimabonus online, then receive quotes from installers on the official register. Zero advance on the grant — your installer handles everything.
Frequently asked questions about solar pre-financing in Luxembourg
Does pre-financing change the amount of my Klimabonus grant?
No. The grant amount is strictly identical whether you choose pre-financing or the classic route. The only difference is that with pre-financing, it is your installer — not you — who advances the amount and waits for State reimbursement. You ultimately pay exactly the same total either way.
What happens if the State takes more than 15 working days to respond?
The « silence equals agreement » principle applies automatically: the application is deemed approved after 15 working days without a response. The State must then make payment to the installer within the following 15 days. This legal mechanism protects installers against administrative delays.
Can I benefit from pre-financing for a battery added to my existing panels?
No. Pre-financing only applies to new photovoltaic installations, with or without battery from the outset. A battery added alone to an existing installation must go through the classic post-financing procedure. If you plan both together, include panels and battery in the same initial order.
Is pre-financing compatible with the Enovos guaranteed feed-in tariff?
No. The guaranteed feed-in tariff (€0.1374/kWh for 15 years) is incompatible with the new Klimabonus and pre-financing scheme. If your installation operates under a guaranteed feed-in contract, it falls under a different regime and cannot benefit from either. To access pre-financing, you must formally waive the guaranteed feed-in tariff.
Will pre-financing be extended to other works (heat pumps, insulation)?
Yes, that is the government’s intention. The official communiqué of 4 January 2026 states that pre-financing is planned to be « progressively » extended to other Klimabonus Wunnen components. In 2026, only photovoltaic installations (with or without battery) are covered.
Go solar without advancing the grant
Luxembourg’s solar pre-financing lets you start your project with only 30% deposit. Simulate your 2026 Klimabonus and receive quotes from officially registered installers.