Klimabonus solar water heating grants
Grants for solar collectors that supply hot water, with or without additional home heating, in eligible existing Luxembourg homes.
Solar thermal collectors use the sun to heat water. Klimabonus pays a grant towards their investment and installation costs. For hot water alone, a single-family house receives €2,500; an apartment building receives €2,000 per dwelling, capped at €14,000. For hot water combined with additional space heating, the amounts are €4,000 for a house or €3,500 per dwelling in an apartment building, capped at €17,500.
An additional €1,000 flat-rate grant may be awarded when the solar thermal system is installed at the same time as a wood-fuelled boiler or heat pump. Aid is paid only once per installation. The grant is generally paid into your bank account; inaccurate or incomplete declarations, or failure to provide requested information or documents, can lead to repayment.
Eligibility
- The system must serve an existing residential building in Luxembourg. Its invoice must be dated at least 10 years after the building permit was issued; attach proof of the permit date.
- Individuals, private-law legal entities and public legal entities other than the State may apply. Apply as the dwelling owner, or as a legal representative who is also a member of the applicant group. If ownership changes, the former owner who paid for the investment may receive the aid when the new owner of the dwelling and/or installation gives up that aid in their favour.
- The collectors must carry the European Solar Keymark certification. The installation must include a heat meter (calorimeter) that measures the heat produced by the solar circuit. If it also supplies additional space heating, the collectors’ gross surface area must be at least 9 m² for flat-plate collectors or 7 m² for vacuum-tube collectors.
- Unglazed collectors with polyethylene pipes and hybrid collectors producing both hot water and electricity are excluded. Second-hand systems and replacement, repair or exchange of a component that cannot work independently are excluded. An installation already subsidised under the 2017 or 2022 scheme is ineligible.
- A legal entity carrying out an economic activity receives aid under the EU de minimis rules, which limit the business’s total aid under that regime. It must identify whether the aid is registered in its name or transferred to another recipient; a transfer requires formal proof and the final recipient’s name and identification number.
How to apply
- Status
- Open continuously
- Round restrictions
- Eligible standard-route invoices must be issued between 1 January 2026 and 31 December 2030 inclusive. Apply within four years after 31 December of the invoice year.[^c5]
- For installations concurrent with energy efficiency renovation of an existing building, invoices may be issued through 31 December 2035; applications must arrive by 31 December 2039 and also meet the four-year invoice-year rule.[^c5]
Check with the municipality where the building stands whether a building permit is needed. After completing the work, apply through MyGuichet.lu or its mobile app using LuxTrust or an electronic identity card. Alternatively, post or hand in the appropriate DEPA-2026 form at the Single point of contact for housing assistance, 11 rue de Hollerich, L-1741 Luxembourg. Use the individual or legal-person form according to your applicant status; the Environment Agency administers the grant.
Include bank-account identification and detailed invoices, each with valid proof of payment: a bank stamp or a bank debit notice. Attach any itemised quotation referenced by an invoice, plus the SOTH-2026 technical sheet. The sheet can be completed and signed by your energy adviser, the person who calculated the energy performance, the project architect or the company responsible for the work. Include proof of the building-permit date and an energy performance assessment if applicable. Incomplete applications or annexes are returned.
If you use the optional solar thermal conformity certificate instead of detailed cost invoices, the person or company responsible for the work must complete, sign, stamp and date it. All deposit, final or overall invoices must still accompany it, each with a bank debit notice as proof of payment.
For a jointly owned or apartment building, provide COLL-2026 and PROC-2026 authorisations for each owner, or the general-meeting record or another official document confirming the owners’ decision to carry out the project. Include the list of apartments and each apartment’s energy reference area, excluding common areas. Energy reference area means the net area that is heated or cooled, generally the heated living area; use this energy-calculation measurement for each apartment. A group representative receiving the payment must immediately transfer each member’s share to them and send copies of those payments to the Single point of contact.
For the standard route, eligible invoices run from 1 January 2026 to 31 December 2030. Apply no later than four years after 31 December of the invoice year. When the installation accompanies energy efficiency renovation of an existing building, invoices can run to 31 December 2035 and applications to 31 December 2039, while the four-year rule still applies.