Clean Power

Published on August 17th, 2013 | by Nicholas Brown


Largest Solar Rooftop In Europe Complete, In Germany!

August 17th, 2013 by  

The largest self-consumption rooftop solar array in Europe has been completed, and it is of course located in Germany. It is eleven hectares in size, consists of 33,000 solar panels, and has a generation capacity of 8.1 MW (which could power up to about 1,846 homes).

The record-breaking solar roof is on top of the Pfenning Logistics distribution centre named multicube rhein-neckar, which is located in the Heddesheim municipality, a bit south of Frankfurt. The building was recently constructed and has been owned by Union Investment as of 2012.

Dennis Seiberth, president of international large-scale projects at the project development company Wirsol, said: “In this size we usually build solar parks.” He added that Wirsol was ambitious in its aims to build the plant in four weeks.

Largest solar rooftop in Europe. Image Credit: Wirsol.

The power plant was connected to the grid in July.

“We are happy that we can now partially generate electricity by ourselves,” said Karl-Martin Pfenning, owner and managing partner of the Pfenning group. “With the photovoltaic installation we can annually save up to 5, 171 tons of CO2.”

Germany has one of the most successful solar markets in the world, and while many now know that, it is still quite impressive that a cloudy country could have such a successful solar market. It also makes one rethink the misconception that solar panels only work in direct sunlight.

I own a solar panel, which I have been running numerous tests on for over a year. It works in all weather. However, power production does decrease to an extent when the weather is cloudy. The darker the sky is, the less power the solar panel generates. The good side to this is that air conditioner power demand decreases along with solar power production when the weather becomes cloudier, reducing the need for solar backup.

The results of some of my tests can be found here.

Check out our new 93-page EV report, based on over 2,000 surveys collected from EV drivers in 49 of 50 US states, 26 European countries, and 9 Canadian provinces.

Tags: , , , , , , , , , , ,

About the Author

writes on CleanTechnica, Gas2, Kleef&Co, and Green Building Elements. He has a keen interest in physics-intensive topics such as electricity generation, refrigeration and air conditioning technology, energy storage, and geography. His website is:

  • mony1
  • Bob_Wallace

    It doesn’t make financial sense to store more than ~3 days of power in batteries.

    • Too bad. Where I live that might be just right, but we do get a lot of sun.

      • Bob_Wallace

        I think the battery issue will change. EOS Systems is manufacturing a zinc-air battery which should be an incredibly cheaper option than the lead-acid batteries most off-the-grid people now use.

        If their battery works as claims and is offered to the public for the price they are stating then it would make sense to install more storage and rarely have to use backup.

  • Ivor O’Connor

    So what percentage of their power will they be generating? What is it that this company does? How long will it take to pay for itself? How did they choose that exact angle to extend their power? Do they have any calculators that take in hundreds of parameters and spit out the best 10 options?

  • CaptD

    Great news for Germany and all those in other countries that look to Germany to model the way on how to use Solar (of all flavors) in their own countries.

    Germany’s solar success it is very important to all those that want to promote the use of solar because it allows them to tout how effective solar installations are for Germany, since otherwise their own countries traditional non-solar utilities will only promote for more of the same “old school” energy technology, since it will help these utilities maintain the status quo and their market share!

    Every solar installation installed will help get the next solar installation installed!

    I look upon each installation as yet another step forward toward Energy Freedom, which will hopefully lead to a safer Planet, where countries are not wagging future wars for Energy resources. If we can get the cost of Solar (of all flavors) reduced to the point where it is cheaper to install Solar (of all flavors) instead of wage resource wars, then mankind will have a far better chance of survival!

    + Kudos to Bob_Wallace for his moderation expertise, you are a hero to many!

  • Robert

    The rush into renewable is endangering the whole of civilization and progress. This planet is not a stable platform for live and a small cosmic event can easily take all solar and all wind out at once.

    • Bob_Wallace

      Right, Robert.

      Now put on your tinfoil nightcap and let your mother tuck you under your bed.


      • Robert

        Bob, you think that there is somebody that will look after humanely if we fail to look after our selves?

        • Bob_Wallace

          Nope. That’s why we need to get our butts in gear and install a lot more solar and wind that we’re putting on line right now.

          If we don’t turn around this climate change problem we’ve caused then we’re going to fricassee ourselves.

          • Robert

            Bob, then we have the same concerns and view but most likely a different way of thinking how cavitation can progress and survive. Are you interested in history? Did you by any chance read the book by Jared Diamond ‘Guns, Germs and Steel’? This is also on video.

          • Bob_Wallace

            We probably do have different ideas about how civilization can best progress and survive.

            I’m not likely to find a lot of common ground with someone who is calling on slowing down solar and wind energy because the Earth might get hit by a meteor.

          • Robert

            Professor Brian Cox sad “I don’t know if there is other intelligent live somewhere in the universe, if there is not, that would make human life even more pressures.”

            In my opinion, only way for humans ultimately to survive
            is to progress and I am not too sure that solar and wind power will progress human kind and help to provide a safe platform for future intelligent live.

            Historically, this planet has been changing all the time and from time to time it has wiped out most of live that was there at the time or in the wrong spot.

          • Bob_Wallace

            Having lived with solar for over 20 years, observed wind for more than 30 and fossil fuels/nuclear for even longer I’m pretty convinced that we can have a nice future with renewables.

            There’s something to be said for an energy source that needs no fuel, produces no dangerous or problematic wastes and delivers for a good price.

            Keep on thinking. Maybe you’ll figure out what you think works.

          • Robert

            That would be wonderful if that would work like you implied.
            But power generation is only a part of the energy equation. How do you think we should fuel, air planes,
            ships, trucks earth moving equipment and so on?

          • Bob_Wallace

            First, we should move moderate length air travel to electrified high speed rail. That would cut our need for liquid airplane fuel by half.

            We should move most of our freight to electrified rail, using trucks for only ‘the last mile’. And those last few miles could probably be done with electricity/batteries.

            We probably can’t move everything to electricity/batteries but we can dispense with most of our petroleum use. What has to have liquid fuels can be supplied with biofuels and to the extent that we can’t produce enough we could continue using a small amount of oil.

            That’s what we can do right now with the technology we have in hand. Later we might invent batteries that store as much usable energy as liquid fuels.

            (Remember, a tremendous amount of the energy in oil is lost as waste heat. The most efficient diesel engines turn only about half of the energy in a barrel of diesel into kinetic energy, the rest is wasted. And energy is used getting the oil from ground to diesel in the tank.)

    • Ross

      What nonsense. An event big enough to take out all solar and wind would take out pretty much everything else including the fossil fuel supply.

      • Robert

        That is my point. There are several events’ that can happen
        that would wipe out or put humanity back into Stone Age; Yellow Stone National Park super volcano as an example can create a global winter in almost total darkness for several years. What do you think we can do to prevent this from happening?

        • Bob_Wallace

          A super volcano? Not much if anything. But what does that have to do with minimizing climate change?

          Back into the Stone Age. That is not going to happen. If enough survive to start breeding a new group of humans they will have the advantage of our accumulated knowledge. They won’t have to reinvent fire and stone points.

    • CaptD

      If an “event” occurs, then I hope you are not forgetting what would happen to the planet if many of the older nuclear power plants all started to meltdown at the same time… Compared to that scenario, “downed” Solar (of all flavors) would be a trivial recycling cleanup…

      Ask The Japanese, they are experts now because they are now dealing with a Trillion Dollar Eco-Disaster called Fukushima, that still is not contained, continues to send radioactive pollution into the Pacific Ocean (via the Sea of Japan) and will continue to do so for decades if not the rest of our lives!

      • Robert

        Almost all nuclear power stations had been designed in the
        sixties and naturally they are not to what is considered an expectable safety standard today and if nuclear would have been developed progressively they would have been replaced in my opinion because of inefficiencies. 73 reactors are under construction and another 450 are planned or proposed.

        All of the will not have the attached danger of the ones in operation now. Some of them will use the future fuel Thorium rather than Uranium with the well-known safety and building cost advantages.

        Nobody got killed because of Fukushima and TEPCO has been incompetent to deal with the problem. You most likely have a better chance to get killed by the Cadmium from your solar collector leaking into your rainwater tank then from anything from Fukushima.

        • Bob_Wallace

          Your nuclear plant numbers are way off.

          People certainly did get killed at Fukushima. People died during the evacuation.

          If you can make cadmium break its bond with telluride and leak into a water tank you’re a freaking wizard.

          Nuclear is a dead man walking. Give it up.

          • Robert

            This is the information I have, please correct me if this is wrong. “There are 435 operating nuclear plants around the world, each reactor a source of zero-carbon energy. And more nuclear plants are being built: 73 reactors are under construction and another 450 are planned or
            Source (Aug. 16, 2013)

            Germany is replacing its Nuclear power stations with coal fired power stations; how is that helping climate change?

          • Bob_Wallace

            Your under construction number is high based on other sources.


            Your initial claim was about a large number planned. A number of those planned will never be built. The plan was begun years and years ago and have gone nowhere.

            Germany’s new coal burning plants are replacing (not adding to) the older plants that either have been or will soon be decommissioned. These new plants were planned and construction was started prior to the decision to close nuclear plants.

            There is no relationship between Germany building coal plants and closing nuclear reactors.

            By 2020, 18.5 gigawatts of coal power capacity will be decommissioned, whereas only 11.3 gigawatts will be newly installed.

            Furthermore those plants will be more efficient, releasing less CO2 per unit electricity produced than are the ones they are replacing.

            And the new coal plants are partially load-following which also helps reduce CO2 emissions.

          • Robert

            Thank you very much Bob, looks like my information was not up-to-date; also thank you very much for your comments, they are very professional with a no nonsenses approach.

            Germany was building 6 coal power stations this year but build 9 now with 5,300 MW capacity; they are going to close one old power station with 1,000 MW.

            As you mentioned, the new super-heated steam power stations are more efficient and better suited to operate with renewables. If we would have had replaced the open bond fires that we are using presently we could have easily saved the 5% that everybody is aiming for. The elections are coming up in Germany as well and it looks to me as SPD and CDU considering a big coalition to sideline the greens. Peter Altmaier has his foot carefully pressed onto to Energiewende brake to stop the power cost increase in Germany. It will be interesting to watch what is happening in Germany within the next four years.

          • Bob_Wallace

            I don’t follow German politics but the tidbits I’ve picked up make it sound like the German fossil fuel industry is fighting hard to stay alive. It may be that the Greens were seeing a lot of progress and slacked off a bit. It could be that anti-renewable forces will gain some political power and slow things down for a while as has happened in Spain.

            People who own fossil fuel plants, coal mines and oil wells certainly know that they are contributing to climate change. They may not be willing to state so publicly, but any half-way intelligent person has to be able to understand the science.

            They know that they are harming the planet but they are putting their personal fortunes ahead of the lives of billions. They are likely to fight hard to maintain their profits. They won’t give up and go away quietly.

            Coal is losing in Germany. The question is how long it will take, how long the coal industry can drag it out.

            Looks like there is some closure happening aside from replacement plants.

            “RWE has announced in their latest report on their first six months results (press release in German) that they plan to take 3.1 GW of fossil fuel generating capacity off the market.”


            There seems to be a large problem with retail electricity prices in Germany. The spread between wholesale and retail seems extreme. And this is a problem that seems to stretch back long before the emergence of renewables and the decision to close nuclear plants.


            “… the average price on the wholesale exchange in June dropped below three cents for the first time ever. Firms that purchase wholesale power now only pay 2.8 cents on the average.”


            How is it that with wholesale rates of less than 3 cents and renewable subsidies adding only a few cents, the retail price of electricity is so high?

            I’ll add some more in a follow-up reply.

          • Bob_Wallace

            This is from a 2009 Economist article explaining the high cost of electricity in Germany

            “The competition regulator is trying to work out why energy prices in Europe’s biggest economy are so stubbornly high, and in some cases still rising, even though oil and gas prices have fallen sharply. It suspects that generators may have been keeping prices artificially high by, for instance, shutting power stations in concert to limit supplies. Finding evidence of that sort of skulduggery may be difficult, and proving it even more so. But regulators need not look too hard to see that Germany’s electricity market is broken and that a flawed liberalisation of the market over the past decade seems only to have entrenched many of its problems.

            The first sign that the market is not working is in Germany’s electricity prices, which are among the highest in Europe, even though it has access to abundant cheap coal. Moreover, Germany’s electricity prices have remained persistently high even at times when they would have been expected to fall. Analysts at Credit Suisse, an investment bank, reckon the slowing economy will reduce electricity demand by about 5%. Coal prices have dropped by half from last year. Yet there is little sign that either falling demand or lower input costs are leading to cheaper electricity. Wulf Bernotat, the boss of E.ON, Germany’s biggest electricity firm, said this month that he did not expect German consumer prices for electricity to fall this year.

            The main reason Germany’s electricity market is not working as it should is the lack of competition. The four biggest utilities in Germany generate more than 80% of its electricity; the top two, E.ON and RWE, more than 60%. Liberalisation has, if anything, exacerbated this. Germany had eight big electricity producers in 1997, before the government liberalised the market, but the number has since fallen by half because of mergers and takeovers, says Uwe Leprich of the Hochschule für Technik und Wirtschaft in Saarbrücken.

            A second problem is that Germany’s biggest electricity generators also own the networks that distribute electricity. Critics argue that this gives them a huge advantage over independent producers, which may struggle to gain access to the networks fairly or, if they do, gain as much information on supply and demand across the grid. The European Commission has long criticised this “vertical integration” but it has had little success in getting its members to agree to force firms to “unbundle” generation and transmission.

            Change is, however, coming on two fronts. The first is that antitrust regulators in Germany seem to have woken up to the fact that the country’s electricity market is not competitive. And the European Commission is having some success in forcing firms to “unbundle” using antitrust powers. Late last year it closed an investigation into alleged price manipulation by E.ON after the utility agreed to sell its long-distance distribution network along with some of its generating stations.

            And over the longer run, ambitious plans to increase the share of electricity from renewable sources may erode the dominance of the country’s four biggest electricity generators. Germany hopes to get as much as 30% of its electricity from renewable sources by 2020, and although few in the industry think the target will be met, there is nevertheless likely to be a huge investment in new generating capacity over the coming decades. Judicious action by antitrust authorities now could ensure that it adds to competition in the electricity market rather than simply entrenching the incumbents’ positions. But because of the high cost of renewable energy, even with more competition in the market, Germany’s power prices are likely to keep on rising.”


            The last paragraph is badly outdated, but the causes for Germany’s high retail electricity prices predate both renewables and nuclear reactor closures.

        • CaptD


          Japanese authority declare emergency, fuel in reactors unapproachable. Till 2021


          And remember that is just one NPP that has gone BAD, what would happen if something like a massive solar flare really brought down the grid for a L-O-N-G time?

    • All our modern technology would be susceptible, and much of it more so than solar or wind. If we get blasted back to the stone age, we’ll have many, many issues. Some related to technology, some not. Waiting or preparing for this is like playing the Lottery—wasted resources.

  • Ronald Brakels

    I think the tilt might just because it makes for a cheaper installation to attach panels to a single support rather than two. The tilt also allows rain to run off them making for better self cleaning and helps keep them free of snow.

    • Pieter Siegers

      Agreed, but of course peak delivered power curve smoothing is another aspect that may have its benefits.
      Then, if you really want to practice day-stretching then of course all panels should follow the sun. I’d be no surprised to see an overall efficiency gain of about at least 30%.
      But of course such an installation would become a problem in maintenance costs and durability which is not at all desirable.

  • Gary Barrett

    good thing it works in overcast weather. I was there four years and saw the sun about two weeks.

  • agelbert


  • Matt

    looks like half are tilter east and half west, to extend the time period of the day they get power. Trading off self use over max power to maximize $.

    • Bob_Wallace

      Day-stretching. Interesting.

      The attached image shows how south-facing solar is wiping out Germany’s midday peak demand and leaving earlier/later peaks. Using a E/W tilt should wipe out much of the remaining peaks.

      • eject

        Since there are 1.8million or so individual rooftop installations all at different longitudes and latitudes with different roof tilts (and by far not all houses do have a south facing roof) they are quite naturally already distributed very widely. In the early days the FIT was so good it didn’t really matter if your spot was ideal you were making a killing anyway. Now the modules and the installation has become so cheap it still makes sense to install in whichever direction as long as there is no shading.

        This drive to install east west is also fueled by the fact that FIT is not as lucrative as the replacement of own consumption.

        The broadness of the install directions can also be seen in the curves published by SMA for each day. Germany did reach >20GW on reasonably nice days between 10:30 AM and 4:00 PM with 32GWp installed. The reached GWp also seems to be limited to something around 28GW since not all arrays can peak at the same time. This is good.

        Furthermore new installations above 10kWp are only allowed to deliver 70% of kWp. I.e. if you have exactly 10kWp in modules installed you are not allowed to deliver more then 7kW to the grid. This is to avoid high loads which will only last half an hour or so on exceptionally good days and would lead to unnecessary regulations in grid management. The excess electricity has to be either wasted or consumed (mostly heating water). Alternatively for very large arrays there is the option that you allow your array to be remotely controlled so it can be turned down on demand. But this is not viable for small installations which is why the 70% hard limit is preferred for home installations.

        In reality there are no huge losses since 100% load is only reached for a couple of hours each year and there is loads of meat below the 70% line.

      • This is a fascinating development, much like the practice of designing for time-of-use (rather than optimal sun). Where can we find more information on this topic, Bob? Searches on “day-stretching” and solar don’t turn up much.Thanks

        P.S. My previous understanding of the East/West orientation was simply to eliminate the un-utilized in a single orientation set up. I’ve also heard it described as “thin-film” racking since thin film works better in low light. It is supposed to maximize morning and evening light.

        • Bob_Wallace

          Day-stretching. I think I just made that term up. (I also own gasmobile. ;o)

          There’s a lot on E/W panel mounting. I’m going to copy over quite a bit from one site…

          Solar electric modules perform best when mounted on the south facing roof in every northern hemisphere location (not taking into account any shading issues). What happens if you do not have a south facing roof, or if you south facing roof is not suitable for solar? Southeast and southwest roofs are the next best options, but east and west facing roofs are not all that bad. In fact, a tilted solar array facing east or west will only result in about 5-15% less energy produced here in Southwest Florida. But which is better?

          Solar Electric Comparison East vs. West

          The tool that is commonly used to estimate solar electric output is called PVWATTS, which was developed by the U.S. National Renewable Energy Labs (NREL). We can enter a variety of variables to determine how much solar radiation to expect at a given location over the course of an average year. NREL uses historical hourly weather data, array
          orientation, temperature, and other factors to determine the expected system performance.

          If we run a PVWATTS calculation for Southwest Florida for a
          hypothetical solar array tilted at 25 degrees (about a 6 in 12 roof), the total average annual radiation per day is 5.26 kilowatt-hours per square meter for a south facing array. The east and west averages are 4.73 and 4.61, respectively. The production losses are 10.0% and 12.4%, respectively. The winner is east!

          Let’s delve into the numbers just a bit to find out why. The chart on the right shows that east and west production are virtually identical from January – April and August – December. However, May – July shows better results for the east facing array. In fact, the east facing array beats the south array in the summer! It’s not immediately obvious why
          this phenomenon exists, but if you dig into the hourly output, there are some clues. Two important factors come into play – weather and temperature.

          In the summer Southwest Florida gets pretty routine afternoon thunderstorms. These thunderstorm occur when the sun is in the western sky at the time that the west facing solar modules should be performing optimally. Generally the mornings have sunny weather, benefiting the east facing array. In addition, temperatures at mid-day and in the
          afternoon are generally much warmer than in the morning. Solar electric modules lose performance in high temperatures (we’ll save the “why” for another blog entry). Finally, the mid-day sun is almost directly overhead in summer in Southwest Florida, so in this particular example with a 25 degree array tilt, east beats south in May – July.

          So if you are asking whether to mount solar panels on the east or west roof, it doesn’t make a huge difference, but east trumps west by a slight margin.”

          E/W at a higher latitude might have/probably have different performance characteristics.

          Thinking a bit more about the mounting in the picture, that much tilt might extend the day a little and eliminate the need for panel washing.

        • Bob_Wallace

          “I’ve also heard it described as “thin-film” racking since thin film works better in low light.”

          Do you know of any numbers?

          I’m thinking of adding some more panels to my house to reduce my backup generator need. It’s the cloudy days what cause me to have to push the starter button. If thin-film is better than silicon then I’d go that route.

          • eject

            thin film is better in terms of yield under cloudy conditions for each installed Wp. But with mono cryst Si you are still getting more power per area because of the higher overall efficiency. If Roof space is you limit go for monos if money is the limit go for thin film.

          • Bob_Wallace

            I’m going to have to see if I can answer my question from the spec sheets.

            I want the best bang for my buck. Space is not an issue, my panels are ground-mounted and I’ve got 60 acres.

            The issue is how to get more power under cloudy conditions. Right now we’ve got smoke blowing in from summer fires some distance away. The high smoke filter means that I’m getting a lot less power than normal. I ran my batteries a lot lower than I normally would last night since I’m swapping them out this fall. And I may have to turn on the generator later today in order to do a bit of woodworking that I need to finish.

        • Bob_Wallace

          Just found a most wonderful site. It lets you calculate the cost of solar-electricity for places all around the world and you can change the mounting direction. That would let one calculate the loss from E/W mounting at different latitudes.

          It defaults to south-facing with azimuth set at 180 degrees. For east or west just change to 90 or 270.

          • Bob_Wallace

            Playing with the calculator a bit…

            Going north to Copenhagen and using $2/watt ($2k/kW).

            At different orientations the array would produce…

            5354.51 krone per year with a 180 degree (S) mounting.
            3642.56 krone with a 90 degree (E) mounting. – 32%
            3517.15 krone with a 280 degree (W) mounting. -34%

            Then getting closer to the equator in Trivandrum, India

            Rs 10,292.96 with a 180 degree mounting.
            Rs 10,010.60 with a 90 degree mounting. -2%
            Rs 10,070.32 with a 270 degree mounting. -2%

    • eject

      it is more economical to have a high self use. They will receive in the range of 14-16 eurocent per kWh for exporting electricity to the grid. Buying electricity from the grid will cost them more (normal retail price is around 24-28eurocent, however a large company might get it below 20 but not below 16). So they are maximising their profit from the array by stretching out the period and trading of the max peak.
      Especially over the whole year.

    • Doug

      With so much solar coming online in Germany, having a few E/W vs South installations would smooth out the production curve, especially the W part.

Back to Top ↑