No more patchwork. For years, the solar obligation in Germany was a matter for the states – with the result that companies and property owners faced completely different regulations depending on their location. Baden-Württemberg was a pioneer, other federal states followed, and still others remained inactive. For owners of supra-regional portfolios, this was a nightmare of conflicting deadlines, different thresholds, and hardly comparable exceptions.
This is fundamentally changing now. With the Building Modernization Act (GModG) the federal government creates a uniform basis for the first time – and the crucial paragraph is called German Works Constitution Act. As of January 1, 2027, it will apply nationwide. Anyone building, renovating, or holding commercial real estate must act now.
What is the GModG – and why does Section 106 exist?
The Building Modernization Act replaces the previous Building Energy Act (GEG) and implements, among other things, the European Buildings Directive (EPBD) into national law. The EU had set the requirement that member states must introduce binding solar requirements for buildings – and the federal government has cast this requirement into concrete paragraphs in May 2026 with the GModG draft.
§ 106 GModG becomes Central regulation for solar energy on buildings in Germany. It is considered technology-neutral for Photovoltaics and solar thermal, relies on a phased introduction and defines clear thresholds – depending on building type and usable area.
For commercial real estate, this is the most relevant innovation of the entire law.
The Staged Plan: When does what apply to commercial real estate?
§ 106 GModG provides for a phased introduction to avoid overburdening the construction industry. The roadmap for non-residential buildings – meaning commercial, industrial, office, and logistics – is as follows:
| Moment | Scope |
| January 1, 2027 | New public non-residential buildings, as well as new commercial and purpose-built buildings with more than 250 m² of usable floor space |
| January 1, 2028 | Existing commercial buildings with at least 500 m² of usable space during major roof renovations; large public existing buildings with at least 2,000 m². |
| January 1, 2029 | Existing public non-residential buildings with a usable area of 750 m² or more |
| January 1, 2030 | All new residential buildings; covered parking that is physically attached to a building (e.g., carports) |
| January 1, 2031 | Smaller public inventory buildings from 250 m² usable space |
Important for practice: The obligation for existing buildings does not apply immediately and unconditionally; it is usually triggered by a Major renovation of the roof triggered. Anyone who is about to fundamentally renovate their commercial building with a usable area of 500 m² or more must also install or have a solar system installed from 2028 onwards.
Solar-Ready: The obligation begins during the planning phase
An often underestimated aspect of Section 106 of the GModG does not concern the installation itself, but rather the Planning. In the future, new buildings must be designed in the drafting phase to optimize their solar potential – the keyword here is „solar-ready.”.
Specifically, this means that the roof orientation, structural reserves, conduit routing, and installation spaces must be designed from the outset for later or simultaneous solar use. Those who ignore this risk expensive retrofits or preclude the possibility of operating the system economically.
For builders who apply for building permits or develop projects today, the solar-ready requirement is not a nice-to-have – it is a legally anchored planning basis.
Exceptions and hardship clauses
The law provides for situations where the installation obligation does not apply. The most important grounds for exemption are:
- Historic preservation Buildings under monument protection are generally excluded, unless the monument protection authority grants an exception.
- Technical impossibility If the installation cannot be realized for static, constructive, or technical reasons.
- Economic unreasonableness When the costs are out of proportion to the achievable benefit.
- Avoid double taxation: Buildings that are already subject to mandatory extensive renovations under § 40 GModG are temporarily exempt from the solar obligation – to protect owners from a simultaneous double burden.
For owners and asset managers, this means that a blanket invocation of exemptions is not possible. The reasons must be documented and, if in doubt, proven. An early review – ideally as part of a technical due diligence – is advisable.
Implementation by third parties possible
§ 106 GModG expressly permits the duty to be fulfilled by third parties – for example, through Contracting. This means that owners are not required to invest their own capital. A Contracting provider handles the planning, financing, installation, and operation of the system—thereby enabling the owner to fulfill their legal obligation without committing any of their own capital. This is a particularly relevant model for property owners and asset management companies with tight capital expenditure budgets or complex ownership structures.
State law remains – and can be stricter
The GModG sets a nationwide minimum, but no nationwide maximum. It is expressly regulated in paragraph 4 that the states can set further requirements through state law. Existing, stricter regulations – for example in Baden-Württemberg, NRW, Hamburg, or Bavaria – remain fully in force.
This has an important consequence for owners of portfolios spanning multiple regions: the nationwide solar obligation according to § 106 GModG is the new minimum standard. Whether state law applies beyond this must be examined on a location-specific basis.
For federal states with little regulation so far, such as Mecklenburg-Western Pomerania, Saarland, Saxony, Saxony-Anhalt, and Thuringia, the federal law, on the other hand, means a real cutback – from January 2027, the new solar obligation will automatically apply there, without state laws acting as a buffer.
An up-to-date overview of country-specific regulations with all thresholds and deadlines can be found in our articles “Where is there a solar panel mandate for industry and commerce?” as well as“Solar obligation for real estate“.
Parking Lot PV: What State Law Regulates – and What the GModG (Still) Doesn't Mandate
An important point that is often overlooked in the discussion about § 106 GModG: The federal law exclusively regulates the solar obligation on and on Buildings. For commercial parking lots - meaning open-air parking spaces without direct building connection - the respective state regulations will initially remain in place.
Several federal states have already introduced binding regulations here. A selection of the most important ones:
- Baden-Württemberg PV obligation for new commercial parking lots with 50 or more spaces since 2022; one of the strictest regulations nationwide.
- Bavaria PV obligation for newly built canopies over commercially used parking lots with 50 or more spaces.
- Hamburg: PV obligation for new parking lots above a certain size within the framework of the State Solar Act.
- Hesse: Mandatory requirement for newly constructed parking lots with 50 or more spaces applies to state-owned and commercial areas.
- Bremen Solar obligation for non-residential buildings and larger parking lots with 35 or more spaces already in effect since 2023.
Able January 1, 2030 Does the GModG then also apply to a specific area: Covered parking spaces that are physically adjacent to a building – such as carports or integrated underground garage entrances with canopies – then fall under the federal regulation.
For all other commercial parking spaces, check state law, as regulation remains fragmented here.
What does this mean strategically for developers, owners, and asset management companies?
For builders and project developers
Anyone planning a commercial building with more than 250 m² of usable space today is doing so under the conditions of § 106 GModG. The solar system is no longer an optional additional investment, but a mandatory component of the project – and should therefore be included in the economic feasibility study early on.
A well-sized PV system reduces energy costs, increases the property's attractiveness, and can contribute to returns through direct marketing or self-consumption optimization, depending on the model. Those who plan photovoltaics as an integral part of the building concept rather than as an imposed obligation will get significantly more out of it.
For existing customers
For owners of existing commercial properties, the crucial question is: When will a major roof renovation planned or due? Because starting in 2028, that's exactly what will trigger the solar obligation – for buildings with a usable area of 500 m² or more.
This means two things: Firstly, upcoming renovation measures should be checked for their solar obligation relevance at an early stage. Secondly, it can make sense to intentionally combine renovation and PV installation – this reduces scaffolding costs, coordination effort, and construction disruptions.
Owners who have to invest in the coming years anyway should start planning now – not just when the obligation comes into effect.
For asset managers and fund companies
For institutional investors managing commercial real estate portfolios, Section 106 of the GModG is more than a compliance issue. It changes the Valuation basis of objects and the Risk structure entire portfolios.
Specifically: Properties without a PV system will no longer be considered compliant with the law from 2027/2028 onwards, once a major roof renovation is due. This will impact their rentability, ESG score, and in extreme cases, their financing capacity—as banks and investors increasingly consider the climate compliance of properties as a lending risk criterion.
We recommend conducting a systematic portfolio analysis: Which properties will require renovation by 2030? Where and when does the solar mandate apply? Which properties offer the best conditions for a cost-effective PV system? And for which properties does a Contracting model make more sense than a direct investment?
Those who answer these questions now will avoid future regulatory pressure and strategically leverage the economic opportunities of solar energy utilization.
Conclusion: Legal Obligation and Economic Opportunity
§ 106 GModG is not a bureaucratic burden to be met somehow. It is the signal that the energy transformation of the building stock in Germany is gaining momentum – with clear deadlines, concrete thresholds, and real consequences.
For businesses and property owners in the commercial sector, this means: the question is no longer whether a solar system will be installed, but when and how it will be optimally integrated.
Planning now will save costs later, help you avoid time pressure, and allow you to strategically leverage the potential of your roof space—whether through self-consumption, direct sales, or as part of an energy Contracting.
FAQ: Solar Obligation for Commercial Properties according to § 106 GModG
When does the nationwide solar obligation for commercial properties take effect?
Starting January 1, 2027 – initially for new commercial and purpose-built buildings with more than 250 m² of usable floor space. Existing buildings will follow starting in 2028, when major roof renovations are carried out.
Does the solar obligation apply to all commercial buildings?
For new buildings, the requirement applies from 250 m² of usable space. For existing buildings, it applies from 500 m², but only if a major roof renovation is carried out. Smaller properties without renovation measures are not directly affected for the time being.
Do I have to install PV or is solar thermal enough?
§ 106 GModG is technology-neutral: photovoltaics and solar thermal systems are both permissible. The decision should be based on the actual energy demand and economic conditions.
What if my roof isn't technically suitable?
The law provides for exceptions in cases of technical impossibility, economic unreasonableness, and monument protection. However, these exceptions must be substantiated – there is no blanket exemption.
Do I have to invest myself, or are there other models?
Section 106 of the GModG expressly permits implementation by third parties—such as through a Contracting model. Under this model, a service provider handles the investment, installation, and operation of the system; the owner thereby fulfills the legal obligation without using their own capital.
Does the solar obligation also apply to parking lots?
§ 106 GModG only regulates buildings. For commercial open-air parking spaces, the respective state regulations continue to apply – several federal states already have binding obligations in this regard. Covered parking spaces that adjoin a building will also fall under the federal law from 2030 onwards.
What happens if I don't comply with the solar mandate?
The GModG provides for sanctioning possibilities. The exact penalty regulations are enforced by the responsible state authorities – comparable to previous building code violations. In case of doubt, a missing attachment can also have implications for the building permit or its approval.