Position paper

Mandatory PV installation on every car park?

The intended introduction of a photovoltaic (PV) obligation for existing car parks in France offers an opportunity to investigate whether a similar regulation could be implemented in German law.[1] A PV obligation for existing car parks would have considerable potential in Germany as well: a December 2022 study by Fraunhofer ISE estimated that covering 300,000 larger car parks in Germany with PV systems could produce a technical potential of 59 GWp.[2] But a cursory examination of the legal framework makes it clear that, before this significant potential can be exploited, fundamental legal issues must be clarified. In particular, it is important to consider the fundamental legal implications of a PV obligation as well as the proportionality of such an obligation.

Background: Mandatory solar canopy installation in France

The French National Assembly and Senate have approved[4] the government’s draft of the Law to Accelerate the Generation of Renewable Energy.[3][4] The law is currently before the Constitutional Council for final review.[5] In addition to a number of measures aimed at accelerating the development of renewable energies, the regulations contained in Article 11 provide for an obligation to construct canopies above existing car parks with a surface area of over 1,500 m²; the canopies should include shaded, integrated systems to generate renewable energy.[6] In the explanatory memorandum to its draft law, which still proposed the requirement for car parks with a surface area of more than 2,500 m², the government identified an additional installed capacity of 7–11 GWp that could be realised with the PV obligation.[7]

Previously: PV obligation in Germany only for new car parks

In Germany, PV obligations regarding new car parks have entered into force in North Rhine-Westphalia, Rhineland-Palatinate, Baden-Württemberg, Schleswig-Holstein, Lower Saxony and Hesse.[8]

To date, however, neither federal nor state regulations have been enacted with respect to solar canopies over existing car parks. Given the significant decarbonisation potential that would be associated with a nationwide solar canopy obligation, the solar expansion plans now contained in Section 4 (3) EEG (2023), and the ambitious solar goals of the German governing parties,[9] the introduction of a nationwide PV obligation for existing car parks should be examined within the framework of the German legal system, taking into account the French regulation.

Legislative competence of the federal government

The federal government is likely to have concurrent legislative competence in the field of the economy, including the energy industry, under Article 74 (1) (11) of the Basic Law due to the energy-related nature of a uniform PV obligation, or in the field of air pollution control under Article 74 (1) (24) of the Basic Law due to the connection between a solar canopy obligation and greenhouse gas reductions.

Relevance to fundamental rights

In terms of substantive law, the guarantee of ownership of private parking space owners under Article 14 (1) of the Basic Law and the general principle of equality under Article 3 (1) of the Basic Law must be taken into account. In addition, the freedom to exercise one’s profession pursuant to Article 12 (1) of the Basic Law may be affected if the car park is owned and operated by different parties. In the case of car parks that are publicly owned, the obligation could apply due to the exemplary role of the public sector.[10]

In addition to the question of the opening of the scope of protection under fundamental rights, it should be noted in particular what effects arise with regard to the intensity of interference and justification.

A PV obligation with regard to existing car parks regularly means a considerable encroachment on the property rights of the owners. This is due in particular to the fact that the owners are generally unwilling to invest or have only limited financial resources to do so. In any case, the encroachment on the existing property would likely to be associated with higher costs for the owners than would the installation of the PV system in the course of the planning and construction of a new car park.

From the perspective of proportionality, the national climate protection goals regulated in Section 3 of the Federal Climate Protection Act could justify legitimate purposes for a PV obligation. Regarding the appropriateness of a PV obligation for car parks that have already been constructed, it is necessary to harmonise this with the Federal Constitutional Court’s finding that the state is obligated to protect the climate under Article 20a of the Basic Law, which seeks to achieve climate neutrality, and that the relative weight of the climate protection requirement in the increases further as climate change progresses.[11] In connection with the expansion of renewable energies, the provision contained in Section 2 (2) of the Renewable Energy Sources Act (2023) also states in general terms that renewable energies are to be considered a priority concern when protected interests are weighed against one another in each case. This is likely to establish the effective promotion of greenhouse gas reduction by expanding renewable energies as a central consideration where fundamental rights and legal interests concerned.

Moreover, Article 14 of the Basic Law protects the existence of rights, so that owners may generally rely on the continued existence of rights acquired in accordance with the law. Accordingly, the legislature is responsible for ensuring a smooth transition for the obligated parties. This transition could be designed accordingly in individual cases by means of legally regulated, sufficiently measured transition period, or additional or extended support programmes or hardship clauses, e.g. in the event of economic unreasonableness.

France: Financial support

According to the impact study[12] conducted for the Prime Minister, the expected total investment (CAPEX) in the construction of canopies above all car parks that fall within the scope of the scheme (assuming costs of € 1,200 per kW of installed capacity) amounts to between € 8.1 and € 13.5 billion.[13] In this context, the impact study refers to the fact that obligated parties can choose to make use of public funding opportunities[14] and to generate income by producing electricity with the solar systems that they install; the latter option would cover the investment and the operating costs and create possible profits.[14] In this context, the impact study refers to the fact that obligated parties can choose to make use of public funding opportunities[14] and to generate income by producing electricity with the solar systems that they install; the latter option would cover the investment and the operating costs and produce possible profits.[15] The impact study presents an annual income of € 102 per installed kilowatt hour with a generation capacity of 1200 kWh per year as an example, which would lead to a normal profitability of the investment costs to be borne by the obligated parties.[16]


Within the framework of proportionality, an extension of the PV obligation for existing stock can be justified by the fact that the land can be utilised twice. The installed PV modules generate additional economic value.

In addition, a car park PV system is considered a ‘special solar system’ according to Section 37 (1) (3) EEG 2023. Since elevated PV modules are used here, an extension of the additional bonus granted under Section 38b (1) EEG 2023 could be appropriate to support economic efficiency. So far, this additional bonus is only granted for plants permitted under section 37 ( 1) (3) (e) EEG. These are installations built on peatland soils that have been drained and used for agriculture, if the areas are permanently rewetted with the construction of the solar installation. For existing car parks, this additional bonus could mitigate the costs incurred (ground work, elevated modules, etc.).


Mandatory installation of PV systems on a large number of car parks would significantly accelerate the expansion of solar energy. The potential in Germany is enormous. In particular, the feasibility of mandatory PV installation on existing car parks depends to a large extent on the proportionality of the requirement. In the process of considering the design of a German equivalent, valuable insight can be gained from French regulations regarding the installation, particularly with regard to the promotion of economic efficiency as well as transition periods and hardship clauses.

[1] Tagesspiegel Background, 08.02.2023.

[2] H. Wirth, Aktuelle Fakten zur Photovoltaik in Deutschland, Fraunhofer ISE, 18.12.2022, p. 36: https://www.ise.fraunhofer.de/content/dam/ise/de/documents/publications/studies/aktuelle-fakten-zur-photovoltaik-in-deutschland.pdf (accessed 27.02.2023).

[3] Projet de loi relatif à l’accélération de la production d’énergies renouvelables vom 26.9.2022, n° 889 Sénat: http://www.senat.fr/leg/pjl21-889.html (accessed 27.02.2023).

[4] See for details of the legislative process: https://www.legifrance.gouv.fr/dossierlegislatif/JORFDOLE000046329719/ (accessed 27.02.2023).

[5] https://www.conseil-constitutionnel.fr/decisions/affaires-instances?id=32246 (accessed 27.02.2023).

[6] Texte élaboré par la commission mixte paritaire: Projet de loi relatif à l’accélération de la production d’énergies renouvelables vom 24.1.2023, n° 761 Assemblée Nationale / n° 268 Sénat: https://www.assemblee-nationale.fr/dyn/16/textes/l16b0761_texte-adopte-commission (accessed 27.02.2023).

[7] Projet de loi relatif à l’accélération de la production d’énergies renouvelables vom 26.9.2022, n° 889 Sénat, Exposé des motifs, Article 11: http://www.senat.fr/leg/exposes-des-motifs/pjl21-889-expose.html (accessed 27.02.2023).

[8] See Section 8 (2) (1), 3 (2) Bauordnung für das Land Nordrhein-Westfalen of 21.7.2018, Section 5 rheinland-pfälzisches Landesgesetz zur Installation von Solaranlagen of 30.9.2021, Section 8b (1) Klimaschutzgesetz Baden-Württemberg of 23.7.2013, Section 10 (1) Gesetz zur Energiewende und zum Klimaschutz in Schleswig-Holstein of 7.3.2017, Section 32a (3) Niedersächsische Bauordnung of 3.4.2012, Section 12 (1) Hessisches Energiegesetz of 21.11.2012.

[9] According to the coalition agreement 2021–2025 between SPD, BÜNDNIS 90/DIE GRÜNEN and FDP, the target for the expansion of photovoltaics is approx. 200 GW by 2030; see p. 57: https://www.bundesregierung.de/resource/blob/974430/1990812/04221173eef9a6720059cc353d759a2b/2021-12-10-koav2021-data.pdf?download=1 (accessed 27.02.2023). In 2021, the nationwide installed nominal capacity was around 59 GW, compared with around 10.5 GW in the first survey year of 2009. Cf. data on the installed nominal capacity of solar systems by period from 2009–2021: https://de.statista.com/statistik/daten/studie/13547/umfrage/leistung-durch-solarstrom-in-deutschland-seit-1990/ (accessed 27.02.2023).

[10] As is already stipulated in the context of building heat, Section 4 GEG.

[11] BVerfG, decision of 24.3.2021, Ref: 1 BvR 2656/18, 1 BvR 78/20, 1 BvR 96/20, 1 BvR 288/20, second lead sentence.

[12] Étude d’impact: Projet de loi relatif à l’accélération de la production d’énergies renouvelables, NOR: ENER2223572L/Bleue-1, 22.09.2022: https://www.legifrance.gouv.fr/contenu/Media/files/autour-de-la-loi/legislatif-et-reglementaire/etudes-d-impact-des-lois/ei_art_39_2022/ei_ener2223572l_cm_26.09.2022.pdf (accessed 27.02.2023).

[13] Fn. 12, para. 4.2.2.

[14] Fn. 12, para. 4.2.2. Relevant subsidy programs are not named here in the context of the impact study, apart from a fixed tariff for solar electricity determined by means of a call for tenders. The impact study is based on the most recently determined fixed tariff of € 85 per MWh on average for systems with more than 500 kWp.

[15] Fn. 12, para. 4.2.2.

[16] Fn. 12, para. 4.2.2.


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Dennis Nill

Dennis Nill

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IKEM – Institute for Climate Protection, Energy and Mobility e.V.