Sun for Future - Solar parks on farmland

 First published 3 May 2019 - Version of 07 July 2020 - time to read: 11 minutes 


The Earth Overshoot Day in Germany would actually have fallen on 3 May. The current UN species protection report does not report anything good. The IPCC Special Report on Climate Crisis and Land of August 2019 calls for an urgent turnaround in land use. The Leopoldina presents a 10-point plan on biodiversity. Will man and nature finally come together in the face of the corona and climate crisis?

Now is the time to take the energy transition seriously, because the climate crisis is not a future scenario. The Paris Agreement can be followed by action.

How can solar parks help to make the energy revolution and necessary changes possible? Could this path lead to the goal?

Wildlife Conservation in the Solar Park

Only at first glance are solar parks technical installations that devalue the surrounding landscape and nature. At second glance, solar parks offer enormous potential for nature and species conservation when solar parks are built where intensive farming has been practised up to now.

Areas of arable land with few species are transformed into high-quality, species-rich plant communities for nature conservation purposes. Solar parks offer a special habitat for plants, insects and small mammals, which are rarely found in the intensively used cultural landscape. In this way they make a significant contribution to the conservation of many native species and mysterious wildflowers.

In principle, every solar park offers ecological added value compared to "industrial" agriculture. However, the benefit for flora and fauna is much higher if there is a site-specific biodiversity management concept. 

That means:

    Sowing with different species-rich wild plant mixtures (regional seed)

    Creation of differently structured habitats

    Sub-area specific mowing regime

    Regular monitoring

    6 meters instead of 4 meters row spacing

    80 cm instead of 60 cm ground clearance 

    Fence distance to the module field considerably more generous

Such solar park biotopes enhance the existing agricultural landscape and do not require compensation areas. Instead, a biotope solar park offers compensation areas and could be credited as an ecological priority area or greening area or even receive ecopoints

Why Solar Parks?

Solar parks in Germany are currently profitable at a price of 4-5 euro cents per kilowatt hour for the electricity generated. This also applies to biotope solar parks, because they are built without additional expenses for photovoltaic technology. They no longer need any financial support and will generate electricity even more cheaper in the future. Solar parks are therefore economically reasonable and also serve the purposes of nature protection.

Once the initial investment has been repaid, solar power from solar parks is only charged for operating and maintenance costs. Then electricity prices of less than 2 euro cents per kilowatt hour are to be expected. Since the operating time of a solar park should in principle be unlimited, electricity from solar parks is extremely cost-effective in the long term.

Roof and facade systems may be well suited for the own electricity consumption. For the long-term, secure and inexpensive supply of all sectors I do not see this. Because of the higher installation, maintenance and operating costs, solar electricity from roof or facade systems will always be considerably more expensive than electricity from solar parks.

In detail: Scaffolding for installation, scaffolding for refurbishment and maintenance on the roof, less powerful inverters are more expensive. Downtimes during roof refurbishment, service life of the building, damage to the roof must be considered. There are also not enough roofs and facades to generate the quantities of electricity listed below.

Solar parks are also considerably more efficient in comparison with other bioenergy sources.Here is a comparison with biogas plants operated with silage maize:

A solar park produces per year approx. 700,000 kWhelect./ha, the biogas plant on the other hand only approx. 10,587 kWhelect./ha. The efficiency is 66 times higher with solar power.

If the heat is also used with the biogas plant, the advantage of the solar park still remains with the factor 44.

Where are we - where are we going?

To date, aboute 48 GWp of solar power systems have been installed on roofs and free-field sites in Germany.

The current annual power requirement in Germany is 500 terawatt hours. If one expects losses of approx. 50 % in order to adapt the fluctuating supply of sun and wind to consumption, then all "renewables" should generate 1,000 terawatt hours per year. Of course, considerably more electricity is needed across all sectors. An annual electricity demand of approx. 1.300 - 3,000 terawatt hours per year is likely to be realistic if the primary energy demand of today is taken as a basis.

Solar power, wind power, water power together with short-, medium- and long-term power storage technologies (Power-to-x) could secure a complete power supply from renewable energies until 2050. This study by the Federal Environment Agency already said so in 2013.

The following diagram (based on a template by Prof. Görge Deerberg, Fraunhofer Umsicht) shows what the 2050 Energy system could look like:

Electricity demand is rising from just under 550 terawatt hours at present to up to 3,000 terawatt hours. The energy demand of the transport sector is falling enormously due to a massive reduction in individual traffic and the extensive conversion to electric mobility (battery, overhead line, e-fuels). Demand in the heating and industrial sectors remains essentially the same. New elements in the energy system of the future are the storage (X) in the middle and the waste heat generated by all P2X and X2P processes, which should be used as intelligently as possible and which supplements or even replaces special heat production. Waste heat from industry is integrated as well as possible into the energy system.

The Challenge of Demand for Land

Solar parks require space and are supposedly in competition with agriculture, which cultivates food, feed and renewable raw materials there.

There are various approaches to combine solar parks and agricultural use in one area.   

Agriphotovoltaics (APV) means: combined use of an area of land for agricultural crop production (photosynthesis) and PV electricity production (photovoltaics). APV covers a broad spectrum in the intensity of agricultural use and in the additional expenditure for photovoltaic plant construction. From extensive grassland with no additional expenditure at all on the photovoltaic side to arable crops with special mounting systems. In principle, the agricultural use is not changed by photovoltaics.

However, a biotope solar park is a change of agricultural use. A biodiversity management concept requires suitable regional seeds from native species, a special mowing regime and regular monitoring.  In order to allow flora and fauna to develop optimally, row spacing (6 instead of 4 metres), ground clearance (80 instead of 60 cm) and the distance to the surrounding fence must be greater. In the long term, this creates a species-rich biotope of very extensively used permanent grassland on which, after all, very high-quality roughage can be harvested.

Biotope solar parks on former farmland mean

  • improvement of the soil structure, protection of the soil against water and wind erosion,
  • Preservation and enhancement of biological diversity,
  • Water pollution control, because there is no need to use fertilisers and pesticides,
  • Climate protection by reducing greenhouse gas emissions,
  • Care and preservation of the cultural landscape

Biotope solar parks could be assessed as so-called "ecological priority areas" in connection with greening or as measures of contractual nature conservation.

Bioenergy areas

Due to the considerably better efficiency and ecological advantage of solar parks, it is advisable to first use the areas that are currently used to grow silage maize for biogas plants. This could be done step by step with the expiry of the EEG support for the biogas plants concerned.

In 2018, a total of 1.35 million hectares of land were used for biogas. Of this, approx. 900,000 hectares were used for the cultivation of silo maize.

According to the current state of the art, 600 gigawatt peak photovoltaic capacity can be built on 900,000 hectares of land, generating 630 terawatt hours of electricity per year. Biogas plants operated with silo maize only generate just under 10 terawatt hours on the same area.

The technology of biogas plants can be further used in combination with solar parks from the surrounding area. This enables the necessary Power-to-X technology: production of e-hydrogen, e-methane, E-CNG, e-methanol, gas storage, feeding gas into the natural gas grid, demand-oriented provision of electricity and heat, use of the installed technology, including local heating grid, transformers and grid connection are possible. The fluctuating electricity supply from sunlight could be buffered with redox flow batteries, so that the production of e-Carbon and e-Hydrogen runs continuously.

What to consider

Below are some aspects and wishes for a successful implementation of the energy revolution with biotope solar parks.

  • Even spatial distribution of the facilities throughout Germany to create a biodiversity network that can be used by insects, small mammals and birds (Stepping Stone Corridors). Motto "Every community a biotope solar park"
  • Creation of financial participation opportunities for citizens in the vicinity of solar power plants.
  • Simplification of the authorisation procedure where multiple use is ensured. Multiple use means: Biodiversity concept for species protection or agricultural use or a mixture of both = biodiversity agricultural photovoltaics.
  • Adaptation of EU agricultural subsidies, the Federal Nature Conservation Act and building law to land use by biotope solar parks. Keywords: contractual nature conservation, greening, ecopoints.
  • last, but not least: Increasing biodiversity, water and soil protection serve agriculture. Roughage production is agriculture. Consequently, biotope solar parks and all other forms of APV can also be privileged construction projects according to § 35 Paragraph 1 No. 1, 2 BauGB


In Germany, solar parks are an essential building block for the generation of renewable energy. They are considerably more efficient and ecological than the cultivation of renewable agricultural raw materials for biogas plants.

I therefore consider it advisable to use precisely this bioenergy agricultural land for the construction of agro-photovoltaics and especially for biotope solar parks, when not only biodiversity but also very inexpensive electricity is important.

Requirements of species protection and food production are taken into account by biodiversity concepts and future use with farm robotics.

Solar parks as privileged projects within an agricultural enterprise hand over the planning, project planning and implementation to farmers.

If we install 600 gigawatt peak photovoltaic power in the next 15 years, then domestic  module production is not only desirable but necessary.

Further Links

Ground-mounted PV systems promote biodiversity according to a new study published in Germany. Scientists collected data from 75 MW of solar plants nationwide and found the areas they were located in showed greater diversity and more intact habitat structures and found panels provide a refuge for animals.

The benefits of networked biotopes are demonstrated by 3sat nano on 8 January 2020 in its contributions to the Insect Atlas and Biotopes. The presenter is particularly impressive in broadcasting minutes 10:16 to 10:31. He addresses a different way of shaping and promoting agriculture: "Farmers should actually be able to say something like: I produce five hectares of asparagus, nine hectares of lapwing and one hectare of butterflies." My addendum: Why not put up a solar park on the same hectare as the lapwing and the butterfly and achieve the energy transition and finance the whole thing?

In order not to be suspected of greenwashing, biotope solar parks not only require good planning, but the benefits for the environment should also be measurable. How this is possible is shown by the EULE - project of the Deutsche Bundesstiftung Umwelt (DBU). Project manager Andreas Engl from the Regionalwerke has been combining species protection and energy system transformation for years. 

Naturtalk FÜNF VOR ZWÖLF! - Biodiversity through biotope networks. An interview with Prof. Dr. Berthold. As an ornithologist and former director of the Max Planck Institute for Ornithology, he is known beyond the borders of Germany and is considered an expert in this field. As a member of the Board of Trustees of the Heinz Sielmann Foundation, he is particularly committed to the Lake Constance biotope network and promotes the establishment of a biotope network throughout Germany. His ideas:  Every community to create its own biotope and now simply do it instead of waiting for further research results.

Handlungsleitfaden Solarfreiflächenanlagen: The guide is an important component of the solar offensive of the state of Baden-Württemberg. It is made up of various contributions by authors and provides information on the subject:
- Development, state of development and economic efficiency,
- Planning law,
- civic participation and
- the ecological design of photovoltaic and solar thermal parks.
In addition, the guide presents examples of how biodiversity can be improved in the course of the construction of solar parks.

In this context, Stefan Brunnhuber's books seem to be absolutely right:
In his latest book "Die offene Gesellschaft: Ein Plädoyer für Freiheit und Ordnung im 21. Jahrhundert" (published in February 2019) Stefan Brunnhuber describes how the transition can succeed step by step and with the involvement of the critical public.

In 2016 Stefan Brunnhuber already described a way to meet the global challenges as a society in: "The art of transformation, how we learn to change the world".

The director of the Wuppertal Institute, Prof. Dr. Uwe Schneidewind, on WDR's philosophical radio, is also worth listening to the question: What possibilities are there to deal with the seemingly unsolvable problems of the ecological crisis - and to make the process as meaningful as possible?

How does our society deal with farm animals and what effects does this have on the environment? The Protestant Church tries to give orientation. Among others Uwe Schneidewind speaks in "Diesseits von Eden" of 29.09.2019. WDR 5 ( 04:39 Min.)

Werner Bätzing describes in his current book Das Landleben. He goes far back into the past to sketch scenarios for the future of town and country.
After reading the book, city dwellers think differently about the country. A good book for appreciation and encounter of city and country at the same eye level.

The Deutschlandfunk reports in "Forschung aktuell" from 06.05.2019 in a radio report about the UN report on global biodiversity as well as about the topic of agricultural photovoltaics. Click here to go directly to the podcast.

In this report on the Bonn Climate Crisis Conference - June 2019, Deutschlandfunk in Forschung aktuell, dated 19.06.2019, provides a sobering outlook: Even if all the climate protection agreements of Paris (2015) were implemented, the average temperature of the earth would increase by 3 degrees by the end of the century. One more reason to seriously consider food production without agriculture.

How uncomfortable it will be in the year 2050, no matter what we do now in terms of CO2 reduction, is described here in detail. Understanding rhe climate crisis from a global analysis of city analogues. In this context, greenhouses on many roofs equipped with air conditioning systems fed by solar modules or by cold from deep boreholes could be or become a good idea.

Deutscher Wetterdienst, 2020: Climate Status Report Germany Year 2019, DWD, Climate and Environment Division, Offenbach, 23 pages

What is the situation regarding the achievement of the objectives of the Paris Agreement? The "Production Gap Report", published in November 2019, clearly shows this. It is not good if we continue like this.

Earth’s Future is a transdisciplinary journal examining the state of the planet and its inhabitants, sustainable and resilient societies, the science of the Anthropocene, and predictions of our common future through research articles, reviews and commentaries.

With the "Barometer of the Energy Transition" the Fraunhofer IEE annually evaluates the state of the German energy transition. The indicators selected for this purpose describe the energy system in its various technical dimensions: end energy, wind energy, photovoltaics, balancing power systems, bioenergy, power-to-gas, batteries, heating sector, mobility sector and investment activity.
On the basis of the actual values from December of the previous year, scenario modelling is used to calculate target values for 2050 and to identify target paths that will enable the energy system to be transformed into a 100 percent renewable energy supply.

The Fraunhofer Institute for Interfacial Engineering and Biotechnology (IGB) does research on methanol production from CO2. The project is called innovative cascade processes for the conversion of CO2 into fuels and chemicals.

Carbon dioxide neutral fuels from air and electricity. The Karlsruhe Institute of Technology (KIT) and the companies Climeworks, Ineratec and Sunfire combine the necessary process steps in a compact plant.

How this works with Climeworks technology on Iceland is shown by 3-sat Nano in 4 minutes. A broadcast from 19.03.2020.

The climate crisis represents an existential, global threat to humanity, yet its delocalized nature complicates climate action. Here, the authors propose retrofitting air conditioning units as integrated, scalable, and renewable-powered devices capable of decentralized CO2 conversion and energy democratization. Crowd Oil - not Crude Oil

The DLF reports on 8 May 2019 on how algae and CO2 become climate-neutral building materials.

E. coli bacteria engineered to eat carbon dioxide. Feat could turn bacteria into biological factories for energy and even food. Nature newsfrom November 27.

Deutschlandfunk reported on CO2 recycling on 4 June 2019. Production of fuels with the help of bacteria. BASF has recognized the potential of Lanzatech, the company mentioned in the article. Bacteria are also working on this topic at Electrochaea GmbH.

An exciting report by Deutschlandfunk from 26.06.2019 on how CO2 could change from a climate killer to a valuable raw material. Methanol can become an essential component of the future energy world.

Critical questions and insights into the current debate about which type of energy system will need which energy networks in the future. Deutschlandfunk Zeitfragen with a revealing and very informative report on 28.01.2020: "Braucht die Energiewende die Stromtrassen wirklich?" 

Local heating - district heating - energy transition - Learning from Danes - The Danish heating market. Making it easy! Short and simple on 32 pages by Tobias F. Langer, Logstor.

Store electrical energy regionally and make it available as electricity and heat. Lumenion does this with high-temperature steel storage tanks.

Facts and figures on agriculture from the Federal Ministry of Food and Agriculture

SWR2 Wissen "Der globale Acker" part 6/10. Less soy, less meat, more variety on the plate and the field - it would be a win-win situation.

Contractual nature conservation, greening, common agricultural policy, first pillar, second pillar, ecological priority areas and so on. You can find more information on websites of the EU and the Federal Ministry of Food and Agriculture (BMEL).

Is agriculture in a solar park eligible? This question is discussed in the judgment of the Verwaltungsgericht Regensburg from 2018, which clearly states: Yes, if the agricultural use is not restricted by this. 

SWR2 Wissen "Der globale Acker" Teil 9/10: The experts agree that agriculture as a whole will become more ecological and that environmental pollution will be reduced by precision farming or even brought to an end by "smart farming" and "digital farming".

The conflicts between agriculture and nature conservation are strong. But the ecological problems are becoming more and more obvious. Expectations of the new German arable farming strategy are correspondingly high. A political balancing act is foreseeable. A report by Deutschlandfunk on 8 October 2019.

Digitisation in agriculture, when the tractor becomes the office. Agriculture 4.0 - a report by SWR television.

Current Facts on Photovoltaics in Germany from Fraunhofer ISE, July 31, 2019

Stromgestehungskosten Erneuerbare Energien with an outlook until 2035 from Fraunhofer ISE, March 2018. Due to the high learning rate of 15%, electricity from large solar parks will undisputedly become the cheapest electricity from renewable sources.

Mertens, K.: „Photovoltaik - Lehrbuch zu Grundlagen, Technologie und Praxis“; updated edition, Carl Hanser Verlag, München, 2018. Prof. Dr.-Ing. Konrad Mertens teaches photovoltaics and sensor technology at Münster University of Applied Sciences and is the head of the photovoltaics test laboratory there. His conclusion in Chapter 11.14 Photovoltaics versus biomass: Compared to photovoltaics, biomass requires about 50 times the surface area to produce electrical energy.

Is module production in Germany or Europe competitive? Two articles in the PV Magazine from March 2020 and August 2019 say: YES.

Informative article of the PV - Magazine online about the technology-open tender in November 2019. Also in the fourth round only solar parks are the winners. This time, however, not even one wind farm project has dared to score in the tender. The results of the joint tender rounds for solar plants and onshore wind energy plants on the pages of the Federal Network Agency.

In many countries and market segments, electricity from solar parks is already the cheapest form of renewable power generation. An EU-PVSEC PAPER from August 5, 2019

Prof. Dr. Görge Deerberg of Fraunhofer Umsicht commented on the annual electricity demand of a greenhouse gas-neutral Germany in a lecture at the annual conference of the Network Kraftwerkstechnik NRW on 27.08.2019 as follows: Energy system 2050: heat, mobility and Power2X: electricity demand GHG-neutral Germany: between 1300 and 3000 TWh (see slide 11 of the lecture: SEKTORENKOPPLUNG: CROSS-INDUSTRIELLE NETZWERKE)

This study by the Research Centre for Energy Networks and Energy Storage (FENES) at the East Bavarian Technical University Regensburg (OTH Regensburg) from 2016 offers a look beyond the horizon:
"METASTUDY, Analysis of cross-sector studies on the decarbonisation of the German energy system, On behalf of the Deutsche Energie-Agentur GmbH".
Author's note: In 2016, the authors of this study may not have been able to foresee that solar power plants in Germany can already be operated profitably today with electricity sales prices of 4-6 cents / kWh and that agriculture with farm robots can be possible in 5-10 years under, between and alongside the installed module.

Why we are morally obliged to help when someone's existence is threatened, read and listen to the two political philosophers Christian Neuhäuser and Arnd Pollmann in a report of Deutschlandfunk Kultur from 05.05.2019. In many situations in life, however, the question of a duty to help is more complicated than in philosophical model cases. What happens when we hear about need and injustice elsewhere? How far does each individual's personal responsibility go? How does it measure itself, and how high does the common good rank in relation to individual claims and rights? Should this moral duty be extended to every kind of existence - including the biosphere? I say: Yes!

All Pictures by Christina Grätz (