The companies of the energy transition

Question and design

Within two and a half decades, the transformation of electricity generation in Germany has produced a corporate landscape of its own. Alongside the large utilities, project developers, operating companies, trade businesses, engineering firms and investment companies have emerged, whose number and form are closely tied to the conditions of subsidy. How this landscape is structured today can be inferred only indirectly from market statistics on installed capacity.

This report describes the energy transition from the perspective of the companies. It asks how many corporations plan, install, finance and operate solar, wind and biogas installations, when they were incorporated, where they have their registered office, how they are structured and managed, and how the recent turn in the solar market is reflected in their insolvencies.

The population comprises 23,273 corporations in the database whose corporate purpose names photovoltaics, wind energy or biogas and biomass, or which are assigned to electricity generation from renewable sources. 1,101 companies are active in more than one technology and are counted in each.

Population and stages of the value chain

Photovoltaics accounts for by far the largest part, with 13,911 companies. Wind energy follows with 4,787, biogas and biomass with 2,893. A further 2,904 companies generate electricity from renewable sources without naming a technology in their corporate purpose; these are predominantly operating companies and subsidiaries of municipal utilities. 870 companies combine photovoltaics and wind energy.

The three technologies differ less in the number of their companies than in their position in the value chain. In photovoltaics, installation predominates: 32.7% of solar companies belong to construction, 13.1% to trade and only 22.1% to energy supply. The rooftop solar system is a product of the skilled trades, and its market is shaped by electrical and roofing businesses, solar installers and specialist dealers.

Wind and biogas, by contrast, are fields of operation and finance. Among wind companies, 31.5% belong to energy supply, 27.1% to financial and holding companies and 25.6% to planning and engineering services. A wind farm comes into being over years through a sequence of companies that secure sites, obtain permits, arrange finance and operate; the construction itself is carried out by a few manufacturers and their service providers.

Waves of incorporation and subsidy law

Scarcely any sector traces the history of its regulation as faithfully as this one. The Renewable Energy Sources Act entered into force on 1 April 2000 and guaranteed fixed tariffs over twenty years. In every year since, companies have been formed whose number rose or fell sharply with each amendment.

Biogas experienced its wave after the 2004 amendment and above all after the 2009 amendment, which increased the bonuses for renewable raw materials and manure. Incorporations rose from 57 in 2004 to 293 in 2010. With the 2014 amendment, which tightly capped the annual expansion of biomass, they fell to 74 and have not recovered since.

Photovoltaics has seen two waves. The first was carried by the high tariffs of 2009 to 2011, with 564 incorporations in 2010; it broke off when the legislator cut the rates drastically in 2012. The second began in 2022 and far exceeded the first. Three causes coincided: rising electricity prices after the beginning of the war against Ukraine, the exemption of small installations from income tax and VAT at the beginning of 2023, and the amendment of the Renewable Energy Sources Act that entered into force at the same time. In 2023, 1,910 solar companies were formed, 2.7 times as many as in 2021. Since then the number has been falling, to 1,065 in 2025.

Wind energy runs more calmly. Its incorporations reached a first peak in the years 2011 to 2013 with up to 214 a year, declined after the switch to auctions in 2017 and have been rising again since 2022, to 338 in 2024. This reflects the designation of additional sites and the declared overriding public interest in expansion, which has eased permitting procedures since 2022.

Regions

Measured against the number of all companies in a state, the energy transition is most densely represented in the north and east. Mecklenburg Western Pomerania leads with 48.1 companies per thousand, followed by Bremen (42.9) and Schleswig Holstein (39.0). The share is lowest in the city states of Hamburg and Berlin and in Hesse, because the rest of the corporate population there is large.

The technologies have their own territories. Wind energy is most densely represented in Bremen and Schleswig Holstein, with 25.4 and 18.0 companies per thousand; with its ports and engineering firms, Bremen is at the same time a centre of the offshore industry. Outside the large cities, Bremen and Bremerhaven are the most important locations. Photovoltaics reaches its highest density in Mecklenburg Western Pomerania (20.7) and Brandenburg (18.1); in absolute numbers Bavaria leads with 3,012 companies. Biogas, finally, is concentrated in Mecklenburg Western Pomerania, Schleswig Holstein and Saxony Anhalt, regions with large livestock holdings and arable land; among the locations, Dorsten, Münster and Lohne stand out.

Structure of the companies

The companies of the energy transition are young. Their median age is 8.0 years compared with 10.3 in the total population, and 46.3% of them were incorporated since 2020. In photovoltaics the figure is 55.7%, among biogas companies only 18.3%.

Their structure reflects the business models. Wind and biogas companies are frequently general partners of limited partnerships (26.0% and 23.1%), because installations of this size are mostly set up in the form of a GmbH & Co. KG and financed with the capital of many limited partners. They more often have a management of several people and more often have participations as their corporate purpose. Solar companies, on the other hand, resemble the rest of the Mittelstand: 13.5% are entrepreneurial companies (UG), 31.4% have more than one person in management.

Project companies and concentration of management

Anyone planning a wind or solar park forms a separate company for each project. This shields liability, facilitates financing and allows the finished park to be sold together with the company. The result is a large number of companies managed by a few people.

This is clearest in wind energy. 26.7% of wind companies have a management in which at least one person runs five or more wind companies, 13.9% one in which that person runs ten or more. 44 people each manage ten or more wind companies; the largest number in one hand is 150. In photovoltaics, the share of concentrated management is 9.1%, among biogas companies 4.1%, because biogas plants are predominantly run individually by agricultural businesses.

The address also reveals the project company. 13.6% of wind companies share their business address with twenty or more other companies; in the total population the figure is 5.8%. Only 3.4% of the companies of the energy transition, by contrast, are contractually bound to a parent company. Among the parent companies with the most recorded agreements are the large utilities and some mid sized project developers.

Insolvencies after the solar boom

The incorporation wave of 2022 and 2023 has been followed by a wave of insolvencies. In 2023, 27 insolvencies of solar companies were recorded; in 2025 there were 170. Demand for rooftop systems declined when electricity prices fell again after the crisis and interest rates for financing rose. At the same time, module prices fell, so that dealers with inventory bought at high cost realised losses.

The burden is unevenly distributed across the stages of the value chain. In the twelve months from July 2025 to June 2026, the insolvency rate of solar companies in construction stood at 25.4 ‰ and that of solar trade at 21.2 ‰. Operators of solar installations, whose revenues are remunerated over twenty years, reached 5.3 ‰. Wind and biogas, at 4.2 ‰ and 4.3 ‰, are well below the total population (8.6 ‰).

The pattern corresponds to what organisational research expects for young companies in a suddenly expanded market. Those who founded during the wave have little capital, little experience and few established customers. With a median age of 4.6 years, solar installers are the youngest group in this report, and 60.3% of them were incorporated since 2020.

Management and origin

The youngest member of management of a solar company has a median age of 47 years, in wind energy 52 and among biogas companies 51 years. In 13.0% of wind companies and 11.8% of biogas companies, the entire management has reached the age of 65. This mainly concerns the community wind farms and farm based plants of the first generation, whose tariffs expire after twenty years. For them, succession, continued operation and replacement by more powerful installations form a single question. 431 biogas companies, 14.9%, explicitly name agriculture in their corporate purpose.

4.9% of management mandates are held by people resident abroad, somewhat more than in the total population (4.5%). Most of them live in Switzerland, Austria, Netherlands, China and Denmark. This reflects the countries of origin of the project developers, manufacturers and investors who serve the German market with companies of their own.

Assessment

The companies of the energy transition fall into two worlds. One is the world of the skilled trades and of trade, in which solar systems are sold and installed. It is young, fragmented, heavily dependent on demand from private households and currently undergoing a shake out. The other is the world of project and operating companies, in which wind, solar and biogas installations are planned, financed and operated over decades. It is secured by long term tariffs, concentrated in few hands and difficult for outsiders to see through.

For suppliers, financiers and service providers, this calls for different approaches. In the solar trades, owners of small, young businesses decide, and their creditworthiness needs to be checked carefully. In wind and biogas, the decision is frequently made by project developers and investment companies that run dozens of such companies; the company with which the contract is concluded is often merely their executing arm. And the installations of the first generation face a wave of handovers and renewals in the coming years.

Method and limitations

Data basis

The basis is the HDH Group database of registered corporations with their registered office in Germany as of 23 October 2026, with 1,158,810 companies.

Definitions

• Company of the energy transition: a company whose corporate purpose names photovoltaics, wind energy or biogas and biomass, or a company generating electricity from renewable sources.
• Technology: according to the terms in the corporate purpose, for instance photovoltaics, solar park and solar installation, wind energy, wind farm and wind turbine, biogas, biomethane and biomass. A company may belong to several technologies.
• Stage of the value chain: the sector of the company according to the classification of economic activities. Installation means construction, operation means energy supply, planning means professional, scientific and technical services.
• Concentrated management: at least one member of management runs five or more companies of the same technology. People are recognised across companies where their details allow this unambiguously.
• Insolvency rate: companies with an insolvency entry between 1 July 2025 and 30 June 2026 per thousand companies incorporated before this period.

Limitations

• The study covers corporations. Many wind and solar parks are run as a GmbH & Co. KG; they appear here only through their general partner company. The number of project companies is therefore a lower bound, especially in wind energy.
• The assignment to a technology follows the registered corporate purpose. Companies that operate a technology without naming it are missing; companies that mention it only in passing are included.
• Incorporations are counted for companies still registered today. For early cohorts, companies deleted in the meantime are missing; the early waves therefore appear flatter than they were.
• The temporal attribution to subsidy law is descriptive. Incorporations have further causes besides tariffs, such as electricity prices, interest rates and the availability of sites.

Literature

• Jacobsson, S. and Lauber, V. (2006): The politics and policy of energy system transformation: explaining the German diffusion of renewable energy technology. Energy Policy 34 (3), pp. 256 to 276.
• Stinchcombe, A. L. (1965): Social Structure and Organizations. In: March, J. G. (ed.): Handbook of Organizations. Chicago, pp. 142 to 193.
• Wüstenhagen, R. and Menichetti, E. (2012): Strategic choices for renewable energy investment: Conceptual framework and opportunities for further research. Energy Policy 40, pp. 1 to 10.

How to cite

HDH Group (2026): The companies of the energy transition. Solar, wind and biogas companies: waves of incorporation, regions, stages of the value chain and management. HDH Group Research, as of 23 October 2026. https://hdhgroup.de/en/reports/energy-transition

The results may be used freely provided the source is acknowledged. For questions on method and data, for analyses to your own definition and for press enquiries, please reach us via the contact page.