Solar Quote: 7 Lines to Check Before Signing in Luxembourg

Why a Detailed Solar Quote is Essential in Luxembourg

Luxembourg's solar market has boomed since 2023. With the introduction of Klimabonus Wunnen 2026, which fully replaced the PRIMe House programme in January 2026, homeowners can benefit from substantial subsidies: up to EUR 10,000 for a photovoltaic system and up to EUR 2,250 for a home battery. But these amounts shouldn't overshadow a simple truth: a poorly written quote can cost you far more than the subsidy you expect.

A complete solar quote should let you understand exactly what you're buying, how the installation will be carried out, and what your obligations are. Too often, quotes are limited to a lump sum and a vague power rating. Without technical details, you can't compare two offers or verify that the installer complies with Luxembourg standards.

This guide reviews the 7 essential lines to check before signing. Each point is illustrated with concrete examples tailored to the Luxembourg context, including current subsidy amounts and pitfalls to avoid.

Line 1: Peak Power (kWp) and Number of Panels

Peak power, expressed in kilowatt-peak (kWp), is the standard measure of a photovoltaic system's capacity. It corresponds to the maximum power the panels can produce under ideal sunlight conditions. In Luxembourg, a typical residential system ranges from 5 to 10 kWp.

The quote must clearly state:

• The unit power of each panel (often between 400 and 500 Wp)
• The total number of panels
• The total peak power of the system
• The exact brand and model of the panels

A typical example: a quote stating "6 kWp system" without specifying the number of panels or their unit power is incomplete. You can't verify whether the installer uses 12 panels of 500 Wp or 15 panels of 400 Wp, which changes both cost and roof space requirements.

Also pay attention to the inverter power. It must be matched to the peak power, usually slightly lower (ratio of 0.8 to 1.0). An undersized inverter leads to production losses, while an oversized one unnecessarily increases cost.

Line 2: Brand and Technical Specifications of Equipment

The quote must precisely identify each component: panels, inverter, mounting system, wiring, and if applicable, battery. In Luxembourg, reputable installers use recognised brands such as SunPower, LG, Huawei, SolarEdge, or Fronius. If the quote remains vague ("high-end panels" or "branded inverter"), ask for a technical datasheet.

Key specifications to check:

• Panel efficiency: above 20% is a good quality indicator
• Product warranty: typically 10 to 15 years for panels, 5 to 10 years for the inverter
• Performance warranty: 25 years with an annual degradation rate below 0.5%
• Certifications: IEC 61215 and IEC 61730 standards for panels

A quote that only mentions "photovoltaic panels" without brand or model is a red flag. It may mean the installer uses variable quality materials depending on batches, or is trying to hide dubious origins.

Line 3: Klimabonus Wunnen 2026 Subsidies and Their Integration

Since January 2026, Klimabonus Wunnen has replaced PRIMe House. This programme, managed by Klima-Agence and Guichet.lu, offers generous subsidies for energy renovation. For photovoltaics, the subsidy can reach EUR 10,000, with an amount of approximately EUR 8,300 for a 10 kWp system. The cap is reached at 15 kWp.

For a home battery, the subsidy goes up to EUR 2,250. These amounts must appear in the quote or in an annex, as they significantly reduce the final cost.

The quote must specify:

• The estimated Klimabonus Wunnen 2026 subsidy amount
• Whether administrative procedures are included (submitting the file to Klima-Agence)
• The condition of submitting before work begins
• The impact of the subsidy on the final price including VAT

An illustrative example: an 8 kWp system with battery listed at EUR 18,000 incl. VAT could drop to around EUR 8,000 after deducting subsidies (about EUR 7,000 for PV and EUR 2,250 for the battery, subject to eligibility). The quote should reflect this reality.

Line 4: 3% VAT and Conditions of Application

In Luxembourg, the super-reduced VAT rate of 3% applies to renovation work on homes over 2 years old. This is a major tax advantage compared to the standard rate of 17%. But beware: this reduced VAT does not apply to all components.

The quote must clearly distinguish:

• Installation and labour (eligible for 3%)
• Supplied materials (eligible for 3% if integrated into the service)
• Any non-eligible options (e.g., charging station)

Check that the quote explicitly mentions the VAT rate applied and the legal basis. An installer charging 17% without justification is costing you money. Conversely, an installer promising 3% on a new build is making an error.

Line 5: Additional Costs and Hidden Fees

A complete solar quote is not limited to the price of panels and installation. Many additional costs can add up and increase the bill by 15 to 30%. The quote must list them explicitly.

A typical example: a quote listed at EUR 12,000 can rise to EUR 14,500 once scaffolding, grid connection, and administrative fees are added. These amounts must be known before signing.

Line 6: Schedule, Deadlines, and Penalties

The quote must specify the work schedule: start date, estimated duration, commissioning date. In Luxembourg, a standard installation takes 1 to 3 days, but grid connection waiting times can reach several weeks.

Elements to check:

• Firm start date or range
• On-site work duration
• Grid connection lead time
• Any late penalties
• Postponement or cancellation conditions

A quote without a precise schedule exposes you to significant delays, especially during peak demand (spring and summer). Don't hesitate to ask for written commitments.

Line 7: Warranties, Insurance, and After-Sales Service

Finally, the quote must detail warranties and after-sales service. In Luxembourg, reputable installers offer:

• Perfect completion warranty (minimum 1 year)
• Two-year warranty
• Ten-year warranty for roof waterproofing
• Panel product warranty (10 to 25 years)
• Inverter warranty (5 to 10 years)
• Optional annual maintenance contract

Check that the installer is covered by professional liability insurance and has a Luxembourg business number. A foreign installer not established in Luxembourg can complicate recourse in case of dispute.

The quote should also mention after-sales contact details: phone number, address, response time. An illustrative example: an inverter that fails after 3 years must be replaced under warranty within a reasonable time, at no extra cost to the client.

How to Verify a Solar Quote: The Final Checklist

Before signing, go through these 7 lines and tick each point. If something is missing, ask for a corrected version. A complete solar quote is a sign of professionalism and protects you from unpleasant surprises.

Don't forget to consult Klima-Agence and Guichet.lu to verify eligibility conditions for Klimabonus Wunnen 2026. Subsidies are granted subject to income and energy performance conditions. An incomplete application can lead to permanent rejection.

Finally, always compare at least three quotes. Price differences in Luxembourg can reach 30% for the same installation. A detailed quote allows you to compare like with like and make an informed choice.