Skylight In Any Room

Despite a glut of introvert memes, humans need sunlight. If vitamin D isn’t your concern, the sun is a powerful heater, and it helps plants grow. Sadly for [mime], their house is not positioned well to capture all those yummy sunbeams. Luckily for us, their entry into the 2020 Hackaday Prize is their sun-tracking apparatus that redirects those powerful rays throughout the house. It uses a couple of mirrors to redirect the light around their shed and into the house. For those who work in a dim office, no amount of work is too great for a peek of natural sunlight.

Movie spoiler alert: We saw this trick in the 1985 movie Legend and it was enough to vanquish the Lord of Darkness.

This project started in 2014 and sat on hiatus for more than five years, but it is back and prime for improvements fueled by half-a-decade of experience. The parts that aren’t likely to change are the threaded struts that adjust the positioning mirror’s angle, the driving motors, and power circuitry. Their first plan was to build a solar-powered controller with an Arduino, DC motors, and sun telemetry data, but now they’re leaning toward stepper motors and a computer in the house with a long cable. They are a finalist this year, so we will keep our eyes peeled for further development.

41 thoughts on “Skylight In Any Room

  1. Isn’t most of the UV-B (source of vitamin D) blocked by the standard glass in most windows. Unless you are using a special, expensive, high temperature glass made from quartz as a window.

    1. It is also blocked by melanine, which explain why in Spain, although having more light hours than other countries, we have smaller levels of vitamin D :(

      So if vitamin D is the reason to make this, better take all into account. It would probably be more effective (and cheaper) to take supplements in your diet (but always under medical control!!!! Vitamin D is liposoluble, so taking too much can lead to hypervitaminosis) than mount an expensive quartz window plus polished metal mirrors (the glass in the mirror also counts).

  2. I had considered doing something to direct sunlight into my place some years ago but found if the mirrors were mounted at a manageable height the direction the light came in ended up shining directly into my face. The mirror needed to be mounted up high to direct the light down to the floor to make the system usable. This was not feasible with the size mirrors I was using ( about 4sqm)

  3. I’ve thought about setting up something like this to reflect sunlight onto our north-facing, uphill, shaded-by-the-house driveway in the winter, to help melt snow and ice. Even after being plowed or shoveled there’s often a significant remnant that takes a long time to melt.

    It’d have to follow the sun and also scan the driveway side to side and up and down like a CRT’s electron beam (but much much more slowly).

    1. – love the idea! Wonder how well it’d work with ice and show not being the most absorbent of light themselves… Guess you just get a bigger mirror if need be? :-) Maybe with a flexible mirror you could change the flex/parabola as you scan for better focus on varying distances?

      1. My thinking is that this wouldn’t be a particularly fast process, just a way to hopefully speed up the melting over 4-7 days.

        There’s usually some black asphalt visible, which would absorb the heat more. Probably a system like this ought to be set up with a computer vision system to aim the sunlight at white/black transitions.

        1. Really interesting idea. You could set up a system to concentrate on a small area to start with. I wonder if you heated the asphalt the heat would spread under the surrounding snow.

  4. Combining a variety of LED and fluorescent light sources, you can come up with a very nice approximation of sunlight in a far more compact, practical package. It works on cloudy days, too.

      1. Interestingly, none of the children from the inside of that scene were the same children as the ones from the outside scenes. Filmed in completely different places with completely different children. Nobody seemed to notice.

        1. That’s called “movie magic”.
          Traditionally, filming is scheduled by location, and always filmed “out of sequence” to reduce cost.
          Bringing in the same cast, (Children in this case) increases the overall budget.

  5. Here’s a slick looking one: https://solenica.com/

    Pretty sure they’ve been dragging out a failed crowdfunding campaign for 4 years without shipping anything though. Which is exactly the timeframe of [mime]’s project, oddly enough. Major respect for picking an old project back up though!

  6. I think heliostats were found at every college and maybe high schools in the old days to provide light for optics experiments and in biology departments to provide light for microscopes. They were typically mounted outside a window. https://www.uvm.edu/~dahammon/museum/heliostat.html Also at explorations into dark areas – replacing the kids with mirrors in the beginning of The Fifth Element.

    The Sun moves a degree every 4 minutes and in this application a mirror rotates at half that rate – Sun goes through 180deg as the mirror rotates 90. I suppose it is a hack to replace a clock motor with a computer and a stepper? There isn’t any special tracking since it is a constant rate. Anyway, a fun project and it must be great to have sunlight all day like that.

    1. Doing it with a computer and two steppers allows the mirror to work everyday as the height of the sun changes through the year. Doing it with one motor, or a clockwork mechanism, would allow it to work for one day.

  7. you can do it simpler than that – I have a very large mirror (left over from a old bathroom) flat on my balcony outside, with a piece of lamented glass on top so I can walk on it… During winter it bounces a couple of square meters of light onto the ceiling inside, making a huge difference to the light, and during summer the reflection doesn’t get inside (due to the angle of the sun).

    1. If you’ve a really tall ceiling, you can take a portion of the top of your window for this. Works better if you’ve standard height windows with a short window above it, then you can use that entire short window.
      Then like the Suntube in other posts, you build a rectangular box that fits against the ceiling (or built-in if a new build), that is lined with a mirror surface of your choice, like plastic mirrors or aluminized mylar. The light bounces its way down that box. Add a diffuser opening in the bottom of the box where you want light. If there’s only one spot for that, optimize it with reflectors directing the light within the box at the diffuser.
      This is limited to the light hitting the window, but you can shade it in summer, or like your balcony, aid it with a mirror directing more light into it.

  8. About 15 years ago I saw a completely passive sistem in a fair. It consisted of a domed collector (probably w/ a Fresnel-like lens) to be put on the roof and a lot of mirror-like inox piping to bring the light where needed. Simple and efficient. No moving parts needed.

  9. Just be careful. I remember an article years ago where mirrors were used to direct light on to either solar voltaics or heat arrays on a house to improve winter efficiencies. The article writer said also that the mirror system shifted one day and nearly set his garage on fire. Also there were complaints from neighbors about glare.

  10. How about solving the problem of the UVB being absorbed by glass by turning the light into electrical energy outside the house with a solar panel, running it inside via a pair of wires, and then turning it back into light with a good sunlamp? One could then skip the motor if the solar panel is pointed right and large enough.

  11. Awesome project and ideas! Really neat paradigm of thinking for sure!

    I think all I wanted to note has been noted. Was thinking for directing to solar concentrators of some sort; whether for cooking, lightpiping, heat exchange or PV’s.

    I have to post this beast also while at since I love the idea of refining (pun intended) R&D using high temperature systems to augment or perform existing processes.

    https://www.youtube.com/watch?v=0tK3s1Vnol0

  12. There’s always aiming and/or using reflectors to direct light onto the ends of a bundle of fibre-optic cable, then routing that bundle or portions of it to where you want the light. Was available commercially, but not for DIY retail builds. I don’t know if it’s still available. With the new fibre-optic cable with high-bandwidth per fibre, I’d guess there’s less fibre seconds that are available cheap for this.

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