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Innovative building integrated Solar / PV Panels

  • 24-10-2021 8:25pm
    Registered Users Posts: 2,414 ✭✭✭

    I was driving around Geneva (Switzerland) earlier this week and randomly came across an interesting example of building integrated solar panels.

    Doing bit of research on Google after, the 99 apartment building has 190kWp installed capacity (facade+rooftop) feeding the building's electricity needs and helping to power a district heatpump for heating and hot water. Sad to see so few building projects take an unambitious approach to renewable production potential.


  • Moderators, Science, Health & Environment Moderators Posts: 19,127 Mod ✭✭✭✭Sam Russell

    What a good approach.

    One floor appears to have the PV panels omitted and trees instead. I wonder why?

  • Registered Users Posts: 1,677 ✭✭✭Deagol

    Would make about 70% of a properly mounted system so payback time is very long - I'd guess something around 15 years. Is it really worth it one has to wonder or is it just a virtue signalling effort? I have panels myself so I'm not against them but I wonder if this is a good use of effort and resources?

  • Registered Users Posts: 1,072 ✭✭✭gjim

    Yeah I think it's more for marketing reasons.

    It ignores one of the greatest benefit of electrification - you don't need to put the generation source right beside the point of consumption because of the magic of "wires".

    For the same cost, you could install 4 or 5 times the PV capacity on some marginal land (which can be far away) based on Lazard's LCOE numbers. In addition, putting panels on buildings like this means that they are not optimally oriented; they will be in complete shadow for half the day unlike traditional ground-mounted panels. And people like having things like trees near where they live - which would be incompatible with a set-up like this.

    Even ignoring that, the panels block half the light reaching the balconies making them dark which sortof defeats the purpose of having a balcony.

    Overall, it's just a bad location for PV panels.

    I wouldn't be surprised if each watt from this building cost 10 times that from a small grid-scale PV installation in a better location. Or alternatively, you could have built 10 times the capacity for the same money if you moved the panels to more appropriate location.

    Despite being a big fan of solar, I think putting panels on buildings like this is a distraction in terms of decarbonising electricity production.

  • Moderators, Science, Health & Environment Moderators Posts: 19,127 Mod ✭✭✭✭Sam Russell

    Would they not be better on the roof?

  • Registered Users Posts: 2,414 ✭✭✭embraer170

    A lot of good points in the responses. My understanding from online research (I wish the quote function would work).

    "One floor appears to have the PV panels omitted and trees instead. I wonder why?"

    That floor apparently has building utilities (heating etc.) and common facilities (playground, meeting rooms etc.) to free up the ground floor for more retail space.

    "For the same cost, you could install 4 or 5 times the PV capacity on some marginal land (which can be far away) based on Lazard's LCOE numbers."

    Switzerland certainly doesn't have a lot of marginal land, and as far as I am aware almost no normal PV built on agricultural land. All solar facilities I have seen driving around have been roof mounted solar. Some regions (Cantons) also seem to have strict building rules mandating in-roof solar panels instead of solar panels added on top of the roof, at least for new builds.

    "Even ignoring that, the panels block half the light reaching the balconies making them dark which sortof defeats the purpose of having a balcony."

    A lot of people with balconies in Switzeland and Germany seem to use privacy screens etc. so maybe doesn't make a huge difference.

    "Would they not be better on the roof?"

    There are also roof mounted panels on that building (and all the other buildings in that district).

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  • Registered Users Posts: 1,072 ✭✭✭gjim

    I also hate the way the new quote function works.

    But I don't buy the "shortage of land" argument - the side of that building has at most 200m2 of panels - about 5% of an acre. Even if you take the entire development, there's maybe a half or a quarter or half of an acre of panels being very generous? Mounting the panels flat in a small patch of land would allow optimal orientation to increase the efficiencies of the panel, slash the capital/installation costs and slash the maintenance costs.

    There's just no getting away from the cost argument for me. The LCOE for roof-top solar is between $150 and $230 per MWh while that for utility-scale is between $30 and $40 MWh (more than I had imagined actually). In other words, mounting the panels on buildings multiplies the cost by about 5. Mounting them on the sides of balconies 10 stories up is likely to add even more to the costs.

    As the electricity it provides is completely uneconomic, for me this type of project is about optics and marketing. Being cynical, developers can stick a few solar panels on the building and then market and sell a regular apartment as being "green" or eco-friendly.

  • Registered Users Posts: 8,394 ✭✭✭Markcheese

    Well yeah it's partly green wash -or it could be an initial step, I suppose they could have put some amount of slope on the panels pretty easily - probably would have affected the look of the building though ..

    How many sides of the buliding are they covering ? Just south and west would probably be most efficient ...

    Slava ukraini 🇺🇦

  • Registered Users Posts: 2,818 ✭✭✭Tea drinker

    But even if it takes 15 years to pay off (are you including inflated energy prices?) it's still a worthy project. I'd assume the panels and infrastructure would last 20 years?

    I've been thinking a similar thing for my apartment but also thinking about solar water heater instead. I don't know enough about the tech to know what's best.

  • Registered Users Posts: 2,414 ✭✭✭embraer170

    There were some questions on the size of the system.

    I might be slightly off but I count 28 panels on the west face and 13 panels on the south. Assuming 1.8sqm for each panel over 11 floors, that should be over 800sqm of panels.

    On the mounting, there might be a little money saved from not installing the normal glass/concrete apartment balcony panels? I am sure it is only a small fraction of the cost of installing solar but could become a factor if such approaches ever become more common.

    I fully agree with the economic arguments you mention but I believe planning laws in Switzerland currently prevent the conversion of agricultural land to solar farms. That is why everything you see is rooftop.

    For anyone who reads French, there is a pretty good description of the system here: Report (Published version)

    It first uses cold water capture from a well a few km away. The water is used to cool a nearby industrial estate and hospital (increasing its temperature) before being fed to a central heat pump for heating/hot water for the different apartment blocks in the district. When the power from the solar system is insufficient, the heat pump is supported from a district central heating system powered by Geneva's waste incinerator.

    It seems a bit more than mere greenwashing from a developer (and there is definitely plenty of that going on around Europe).

    They are covering 2 sides (South and West).

  • Registered Users Posts: 6,564 ✭✭✭Pete_Cavan

    There would be define savings in installation costs when installing as part of the main build (both in terms of designing the fixings into the building and having all the necessary resources on site already) plus offsetting the cost of alternative balcony railings. It is obviously designed as part of a much bigger overall system so it's not comparable with individual domestic solar installations.

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  • Registered Users Posts: 3,103 ✭✭✭hi5

    Lots of snow in Switzerland so wall mounted might be better, less clearing.

    Also the winter when its coldest and darkest is when the sun is low in the sky.

  • Registered Users Posts: 1,072 ✭✭✭gjim

    I'm with you fully on the district heating - it's a winner both environmentally and financially. I'm a big fan - where I live now has it and it's great.

    Regarding solar generation in Switzerland - there are a few points. First, I'm pretty sure that there's no law against putting solar panels on land. Panels on rooftops will naturally more noticeable to someone travelling the country. Bigger solar installation are naturally sited away from valuable land especially around towns or cities so you are far less likely to encounter them or see them.

    What I do know is that Switzerland is only in the process of liberalising its electricity market to allow private operators to bid to provide generation capacity to the grid. Nearly all the renewables added to the grid across Europe in the last decade has been added through this mechanism which happened after the EU liberalized the electricity market.

    I think you might underestimate the cost of installing PV panels on buildings - it's hugely more expensive than mounting them on frames over flat land. Installation costs dominate the cost of domestic solar.

    I just think the situation is too urgent to justify putting PV panels on buildings when we could (for the same money) put 4 or 5 times as many panels on flat land. For me, if theres $10m to be spent on solar generation, then, I'd prefer seeing the money spent on grid-scale solar yielding 10MW of capacity than spent on putting panels on buildings yielding 2MW.