Can You Really Build a Solar Panel Out of Old CDs?

Debunking YouTube videos that claim to show DIY photovoltaic cells

Recently, one of those DIY hack videos popped up on one of my social media feeds. In it, the creator claimed "I turn CD/DVD into a solar panel," which seemed interesting but improbable. So, I started watching the video and thought, there was no way that this could work—is there? I understand, basically, how solar cells, or photovoltaic cells, work. And, I really doubted that this proposed hack could work, despite the video showing a multimeter hooked up to the makeshift solar cell indicating that it did.

It's important to understand how a photovoltaic cell works—they’re actually fairly simple, with three parts sandwiched together. The top and bottom are conductive contacts, while the middle is a semiconductor. Semiconductors are materials that allow electricity to flow through them, at a rate somewhere between that of an insulator—which does not—and a metal—which does so efficiently.

One of the most common semiconductors is silicon, which is what is used in photovoltaic cells. When the silicon is bombarded with photons—essentially energy from light—electrons are freed. Collecting these free electrons is how we get electricity from the photovoltaic cell, although it is a little more complicated than that. The silicon is manipulated to release the freed electrons in one direction, towards an outside layer of the cell which becomes the negative leg of the electrical circuit. As the free electrons leave that side of the silicone layer it creates a deficit on the other outside layer, which becomes the positive leg.

Back to the video, it shows someone wrapping copper wire around a CD or DVD, going through the center hole, and working their way around it until it is covered on both sides. This leaving the two ends of the wire next to each other. To keep the wires anchored and isolated from each other, presumably, they’ve each been passed through holes drilled in the CD. So, here is the first problem I see with the video. There is one wire wrapped around the top and bottom sides of the CD, so the top and bottom terminals or wire ends are not isolated from each other. And, even if that worked, there is a second problem. The wire appears to be plain copper wire, which touches where it is bunched up around the center hole—this would cause a short circuit situation.

In any event, I built one of these "cells," as shown in the video, to test—it generated zero current as I expected. One can only guess why someone would create a DIY video for free electricity that doesn't work. And, they’re not the only ones. Doing a search for "DIY CD solar cells" yields a lot of videos. Some mimic the one I originally saw, some use slightly a different design, but are equally ineffective.

In the video, "Free Energy 100% , How make solar cell from CD" they use 3 Zener diodes inline, in a loop of copper on one side of a CD. Doing this may generate some measurable voltage, but it has more to do with the diode than it does the CD or the elaborate copper wire arrangement. When excited by energy, either electricity, or heat from sunlight, the silicon in the diode can release freed electrons, similar to a photovoltaic cell, but not at a voltage or amperage that is actually useful. It would take an absurd number of Zener diodes to create a useful electric current.

In a third video "Homemade 30W Photovoltaic Solar Panel" the creator proposes building a panel using 15 CDs. This design seems to try to mimic a traditional photovoltaic cell, with the CDs fulfilling the role of the silicon semiconductor, and aluminum foil as the contacts on the top and bottom layers. There is a big reason why this design won't work, aside the CD not being a semiconductor that can direct its freed electrons: The aluminum foil used to connect the top side of the CDs is taped down to hold it in place and in doing so, it comes in contact with the lower sheet of aluminum foil which would short out any circuit that might have been created.These too-good-to-be-true hacks, are just that. Videos like these might be interesting or at least entertaining, as evidenced the number of plays they’ve received. But, do your research before spending your time and money on a project destined to waste both. Trying to reproduce the results in these videos is futile.

Brad Ford has spent most of his life using tools to fix, build, or make things. Growing up he worked on a farm, where he learned to weld, repair, and paint equipment. From the farm he went to work at a classic car dealer, repairing and servicing Rolls Royces, Bentleys, and Jaguars. Today, when he's not testing tools or writing for Popular Mechanics, he's busy keeping up with the projects at his old farmhouse in eastern Pennsylvania.

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