A Solar Freakin’ Walkway

Looking to add a little pizzazz to your back garden? Are those strings of lights hung in the trees looking a little dated? Why not try lighting your garden path with DIY solar-powered pavers?

If [jfarro]’s project looks like a miniature version of the much-touted solar freakin’ roadways concept, rest assured that there are huge differences. For one, these lighted pavers actually work — trust me on this; I live not far from the demo site for the Solar Roadways and the degree to which it underwhelms cannot be overstated. Granted, a garden path is a lot simpler to engineer than a road, but many of the challenges remain.

Using recycled glass blocks that are usually reserved for walls and windows, [jfarro] figured out how to attach Neopixel rings to the underside and waterproof them with a silicone conformal coating. The 12 lighted pavers he built draw considerableĀ current, so a 45-watt solar array with charge controller and battery were installed to power the pavers. An Arduino and a motion sensor control the light show when someone approaches; more complicated programs are planned.

Hats off the [jfarro] for taking on a project like this. We don’t often see builds where electrical engineering meets civil engineering, and even on a small scale, dealing with dirt, stone, and water presents quite a few challenges. Here’s hoping his project lasts longer than the Solar Roadways project did.

22 thoughts on “A Solar Freakin’ Walkway

  1. This guy seems to have had much better luck than I did. 7 years ago my girlfriend had her driveway redone with pavers, mostly so she could have paver lights. We used commercial ones made by Kerr lighting. That project has become the bane of my existence. Problems with copper-clad-aluminum wire and bad connections, corroded sockets and bulbs (she lives at the beach) plagued me for the first 3 years. Then I spent 2 weeks pulling up a bunch of the pavers in the hot Florida sun and replacing and rewiring everything from scratch. I replaced the incandescent bulbs with pixels, used heavy gauge real copper wire, ran it thu conduit, soldered, heat-shrank, and siliconed everything. Not really an improvement to the situation, as the pixels kept failing at a very high rate and had to constantly be replaced involving more soldering, heat shrink and silicon. Then there were the problems with data corruption, forcing me to pull everything back up again and replace the plastic conduit with metal. When it worked, it was awesome. An Arduino flashed the lights in all sorts of different colored patterns, including some for each major holiday. (Green and red for Christmas, red white and blue for July 4th, pink red and white for Valentines, etc….) Then along came hurricanes Matthew and Irma, leaving everything flooded under salt water for days. Next week I have to pull it all up and start all over, again. If you know any voodoo priests that remove curses, PM me.

    1. Silicone is a bad idea for waterproofing electronics, as it is acid binding. It releases acid, which corrodes the copper over time. Many leds are sensitive to such environments, and the cheap pixels are quite bad in terms of quality. They fail of many different reasons, which is quite sad, compared to the great functionality they bring.
      Try different casting materials, and make it pluggable. There are quite expensive automotive watertight connectors, but using silicone grease on normal connectors (acid free, like food approved stuff) helps a lot! Where there is grease, there is no water nor air, so it prohibits a lot of bad things.
      And very important, cleaning up your soldering with isopropyl alcohol gets rid of remaining acids from the Flux! Don’t trust no clean.
      In automotive industry, conformal coating is often considered to be not very helpful, as long as there are ANY residues coming from soldering or pcb manufacturing. We’re talking about tiny amounts of residues. Those + water create paths for small currents, which create local galvanic elements, eating up your electronics :-(

      It’s the smallest thing, which can ruin reliability.

      1. Not all silicone releases acid. If that was the case all out motor car windows would be falling out. Neutral curing silicone releases no acid. Easy to spot, it doesn’t smell like vinegar. That’s because it does not release acetic acid, also known as vinegar. In electrical stuff your solder should never contain acid. only use rosin cored solder.

        1. Unfortunately, if you are using lead-free solder, the flux is very active and will eat away at traces and component leads.

          Which is why I’ve always used lead solder, if I have a choice. Sometimes, you don’t.

          In high impedance and/or high voltage circuits, even rosin flux must be cleaned off.

        2. Thanks everyone for the info about the Silicon etc. The pixels BTW are the flat ‘bar’ style which are encapsulated (not very well) in some sort of epoxy and are _supposedly_ waterproof. Until it invariably cracks anyway. The silicon is meant as an extra layer of protection. This whole installation would probably be much less troublesome though if she didn’t live across the street from the Atlantic ocean.
          No-one knows any voodoo priests?

          1. Silicone meant for building aquariums would be better. There are issues with salt water creeping under the bond between some times of silicone caulk and the material it is stuck to. This came up on the Homebrew_PCBs list I run when people were making their own acid etch tanks from scratch and some silicone sealer would eventually develop leaks.

          2. I can look an old college buddy up if you like, he said he was either going into particle physics, or if that didn’t work out, taking over from his grandfather as a witch doctor in Ghana.

      2. Go get silicone from the auto parts store, that is the kind that is non-acidic. As Murray says, you can tell by the smell when it is curing. Hardware store silicone caulks for tubs and windows tend to be acid curing and will corrode metal away in a very short time. You can tell anyone who has tried to fix a leak around their car windshield with silicone from the hardware store, as the paint will be bubbling up from the rust racing along underneath it.

        Silicone is used in electronics all the time. We have several grades of RTV silicone that we use at work, some are stiff and meant to stay where it is put, some are flowable for potting, some are meant to withstand high temperatures. They are all non-acid curing and are inert.

        Hard potting compounds are trouble, as they are unlikely to expand and contract with temperature at the same rate as your PCB, and so will stress and crack boards and connections.

        Why would you use food grade silicone grease when there is silicone grease made specifically for electrical connections?

        I agree about not trusting no-clean flux for lead-free soldering. It tends to be more difficult to clean off than the other varieties, but any residue left over is unlikely to corrode the board. Leaded flux which is rosin, aka pine sap in alcohol, is fairly inert when cool. But residue from either may spoil adhesion of conformal coatings or silicone potting, and cause leakage currents as you say.

  2. Ahhh… nothing makes you see better in the dark then some bright lights shining directly in your face… Instead of lighting the pavement it shines only up, so you can see the tile that really shines but you can’t see the tile next to it (that has been removed for maintenance and no leaves a treacherous hole you could easily step into and cause a nasty tumble.

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