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• Concept for commercial manufacture

  Joris Wegner • 02/20/2024 at 13:22 • 0 comments

  I've updated my concept for commercial manufacturing, since I believe that it is important to have all the components properly certified if it should ever find widespread adoption.
  
  

• Prototype finished

  Joris Wegner • 01/02/2024 at 14:24 • 0 comments

  
  Well, that took a while - I can't recommend the shops for the 28 mm tubing system I linked in a previous post.
  However, the prototype is now in action. It is not really meant to be mounted this high, but the ledge below the panel predetermines that in this case. I will set up the panel properly in another location soon.
  Things that I would change in the next iteration:
  

  • The equipment feet on the horizontal tube that I use to clamp it into the scuncheon should be more robust, maybe from massive plastic or turned aluminium parts rather than sheet metal. I will try 3d-printed parts soon.
  • The tube construction besides the horizontal bar in the scuncheon is robust, but fiddly to assemble. I am already thinking of other options, probably of bent sheet metal.

• Mechanical construction

  Joris Wegner • 08/24/2023 at 01:00 • 0 comments

  I found this nice modular construction system for workplaces in factories based around 28 mm tubing. That could work well for mounting the solar panels. I don't know the manufacturer, but I found it for sale here and here. I ordered some components for testing. I rendered the construction that seems to be the most promising and used the images for the project thumbnails. I hope everything works out well when the parts arrive.
  

  (Edit in 2024 - TechXXL never responded to my request and the order and delivery process with Maunsystem was very lengthy and riddled with communication problems, so I can't recommend either at this point)

  
  

• Window feed-through 2

  Joris Wegner • 07/25/2023 at 23:52 • 0 comments

  This is probably much simpler and cheaper than the previous approach. A 20 x 0,5 mm copper strip is connected to a 4 mm2 standard solar cable with a crimped-on ring ferrule. Everything is protected by a 3d-printed case for isolation and strain relief.
  
  

• Window feed-through

  Joris Wegner • 07/24/2023 at 23:14 • 0 comments

  In case the commercial feed-through made from flat copper braid proves too flimsy, I will experiment with a flat copper strip. Here are my thoughts that might be a bit overengineered.
  It involves two 3d-printed case halves for isolation with a ziptie slot for strain relief, a lasercut copper strip and a wago clamp to connect everything electrically.
  I can already think of a version that omits the lasercut copper strip and works without the expensive lasercut part.
  I probably also need drainage holes for outdoor use.
  
  

• Second approach

  Joris Wegner • 07/19/2023 at 23:11 • 0 comments

  I see two major problems with the initial approach:

  • wind load
  • not really suited for larger solar panels - due to larger wind load, shadowing of windows below etc

  I thought that it might be a good idea to mount a larger panel vertically leaned against the wall below the window. I hope this lowers the load on the telescopic rod holding everything and lowers the wind load siginificantly. The lower efficiency would more than compensated by the use of a larger panel (that doesn't cost that much more).
  I had a few ideas that I illustrated:

  All these are side views. A is the basic concept. 1 Is a 30 mm aluminium strip with 2 mm thickness that connects the telescopic rod 2 (clamped into the window frame) and the solar panel 3. Two are needed to mount the solar panel. 4 is a spacer between the wall and the aluminium mount. The weight of the panel rests on the telescopic rod.
  
  In B, the aluminium strip rests on the window sill to lower the load on the rod. The problem is that the angle of the window sill is not standardized. 5° are recommended, but much more can be common.
  
  Approach C adds an instrument foot with integrated ball joint to the strip to make the design fit varous angles of window sills. Approach D has an additional strip that has a variable angle and can be adjusted with a setscrew.
  
  In E, the telesopic rod terminates in wall pads with a flat underside that rest on the window sill. This would be a simple approach to lower the load on the bar, but I am afraid that tensioning the bar would actually prevent the whole construction of resting on the sill.
  
  For simplicity, I'm torn between trying approach B for the angle of my window sill or E for flexibility.
  

• Initial concept

  Joris Wegner • 07/19/2023 at 22:51 • 0 comments

  These are my renderings of the original idea I had at university.
  The concept depicts a flat and wide copper conductor that transfers the low voltage current from the panels to an inverter on the inner window sill.
  In this project I am searching fo a DIY approach to achieve the same result or a similar approach that proves to be safer and cheaper.

• Mounting solar panels: First approach

  Joris Wegner • 07/19/2023 at 21:29 • 0 comments

  My first idea was to use a telescopic rod that is clamped into the sides of the window for mounting the hardware. This principle is also used for rods that are clamped into door frames for doing push ups. Those hold 100 kg easily, so I think that this is a promising approach to explore.
  For my experiments I bought a telescopic rod for mounting cat nets on balconies. It is sturdy but overpriced. If my experiments are successful, I will publish details on building one from scratch.

  
  I constructed a simple frame for holding a 100 W solar panel at an ideal angle of 32° from U-shaped aluminium profile and 3D-printed parts. The prototype is mounted in the window of friend's houseway higher than planned just for easier access when tinkering.
  
  

  
  
  Takeaways:

  • Everything seems quite sturdy. I'd prefer bigger pads on the telescopic rod though.
  • I felt more comfortable when the outriggers could freely rotate on the rod rather than when they were clamped down, since vibrations might loosen the rod over time.
  • The threaded rod strut flexes a bit, I would use two when I decide to explore this approach further.
  • I'd replace the printed parts on a U-profile with square profile and U-clamps.

• Getting power into my flat

  Joris Wegner • 07/19/2023 at 21:10 • 0 comments

  I'm not allowed to drill into the walls to pass a cable through, so I see no other option than passing a flat conductor between a window and its frame. Products for doing that exist, but I am concerned that they might not be durable enough in the long term. Here is an example, a flat copper braid crimped into connectors sold by wallbox24.de:
  
  

  
  

  If these don't hold up they would probably not only become a fire hazard, but also be too expensive to replace to make the whole endeavour financially viable. I doubt that they are certified by anybody. Maybe I should ask the dealer.

  If these should not do the job reliably, I had some other approaches to explore:

  • a flat (maybe 0.5 mm) but wide copper sheet with isolation around it that can be bent around the window frame. It could be terminated with large WAGO clamps to connect to regular solar power leads.
  • Maybe certain types of flex PCBs could be robust enough. It could be possible to add traces to detect failures in the power traces.

  I think this problem is the bottleneck for the project. If there is no safe way to do this, the whole idea is worth nothing. If you have any thoughts on this I'd be happy to hear your suggestions.
  

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