Team members Madeleine Laitz, left, and lead author Dane deQuilettes stand in front of a tidy lab bench equipped with oscilloscopes and computers. Laitz has a snazzy yellow jacket that pops compared to the neutrals and blues of the rest of the picture.

More Progress On Perovskite Solar Cells

March 8, 2024 by Navarre Bartz 20 Comments

Perovskites hold enormous promise for generating solar energy, with the potential to provide lighter and cheaper cells than those made from silicon. Unfortunately, the material breaks down too rapidly to be practical for most applications. But thanks to some recent research, we now have a better understanding of the nanoscale changes that happen during this breakdown, and how to combat it.

The research is focused on the topic of passivation, which seeks to increase the useful lifespan of perovskites by studying the surface interface where they meet other materials. Most of the perovskite material is a perfect latticework of atoms, but this structure is broken at the surface. This atomically “jagged” interface introduces losses which only get worse over time. Currently, the best way to address this issue is to essentially seal the surface with a very thin layer of hexylammonium bromide.

While this technique significantly simplified the passivation process when it was discovered, the effect had yet to be adequately characterized to further advance the field. According to lead author, [Dane deQuilettes], “This is the first paper that demonstrates how to systematically control and engineer surface fields in perovskites.”

Prefer to roll your own cells? How about a DIY dye sensitized cell or this thermionic converter model?

Solar Cell Fabric Makes Anything Solar

December 18, 2022 by Al Williams 16 Comments

MIT has been working on very thin solar cells made of a film just a few microns thick. The problem? The cells are so thin that they’re hard to work with. You could make a small solar cell on top of, say, a glass slide, but that’s not all that interesting since you can make perfectly good solar cells that are as fragile as glass using conventional techniques. But in a new paper, MIT researchers describe creating 50-micron-thin fabrics that can generate electricity from solar.

The process still involves using chemical vapor deposition to produce the solar cell on glass. However, the cells are removed from the glass, prepared with electrodes, and then transferred to a piece of fabric which acts as a new substrate.

The fabric used in the paper is a composite fabric known as Dyneema composite fabric. It uses ultra-high molecular weight polyethylene fibers and sheets of Mylar. This material has low weight but a very high strength. A UV cure adhesive bonds the fabric and solar cells.

Honestly, we doubt anyone will be making these in their garages anytime soon. But we would love to see what you could do with a roll of this fabric. Wearables, self-charging laptop bags, or solar-powered instruments in an airborne drone could all take advantage of the material’s flexibility and low weight.

Perovskites Understood

November 27, 2021 by Al Williams 9 Comments

The usual solar cell is made of silicon. The better cells use the crystalline form of the element, but there are other methods to obtain electric energy from the sun using silicon. Forming silicon crystals, though, can be expensive so there is always interest in different solar technologies. Perovskite is one of the leading candidates for supplanting silicon. Since they use lead salts, they are cheap and simple to construct. The efficiency is good, too, even when the material is not particularly well ordered. The problem is every model science has on what should make a good solar cell predicted that orderly compounds would perform better, even though this is not true for perovskite. Now scientists at Cambridge think they know why these cells perform even in the face of structural defects.

Perovskites take their name from a natural mineral that has the same atomic structure. In 2009, methylammonium lead halide perovskites were found to act as solar cells. Conversion rates can be as high as 25.5% according to sources and — apparently — the cells could be as much as 31% efficient, in theory. Solar cells top out — again, in theory — at 32.3% although in the real world you are lucky to get into the high twenties.

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Solar Cells, Half Off

November 6, 2021 by Al Williams 34 Comments

A company named Leap Photovoltaic claims they have a technology to create solar panels without silicon wafers which would cut production costs in half. According to [FastCompany] the cells are still silicon-based, but do not require creating wafers as a separate step or — as is more common — acquiring them as a raw material.

The process is likened to 3D printing as silicon powder is deposited on a substrate. The design claims to use only a tenth of the silicon in a conventional cell and requires fewer resources to produce, too.

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Open Source Solar

July 10, 2016 by Al Williams 66 Comments

What’s the size of a standard euro-palette, goes together in 15 minutes, and can charge 120 mobile phones at one time? At least one correct answer is Sunzilla, the open source solar power generator. The device does use some proprietary components, but the entire design is open source. It contains solar panels, of course, as well as storage capacity and an inverter.

You can see a video about the project below. The design is modular so you can pick and choose what you want. It also is portable, stackable, and easy to transport. The team claims they generate 900W of solar power and can store 4 kWh. Because of the storage device, the peak power out is 1600W and the output is 230V 50Hz AC.

Continue reading “Open Source Solar” →

Setting It Straight About Science Fair Solar Energy Breakthrough

August 22, 2011 by Mike Szczys 58 Comments

There’s been a lot of stories about arranging solar panels to mimic leaves on a tree, thereby boosting their efficiency. But before reading that story you might want to check out this blog post correcting some flaws in that breakthrough (page is down, here’s a cached version).

Before we go any further, we’d like to point out that the original work was done by a seventh grader. He looked at leaves on trees and postulated that the Fibonacci sequence can be found in the layout of leaves, and that by laying out solar cells in the same way you can capture more sunlight. Comments can get negative fast around here, so remember that trashing his work may discourage other kids from participating in science fair events.

Anyway, long story short: there were some issues with original assumptions, and about what was actually being measured during testing. The article linked at the top covers the fact that the cells were not measured under load, and that simple calculations can show why the tree-mimicking-cell-placement can be proven sub-optimal to 45 degree, south-facing solar farms.

[Thanks Jeffery and Steve for the original article and Brian for the follow-up article and cached link]

DIY Solar Panels

September 8, 2009 by James Munns 74 Comments

solar

Reader [unangst] pointed out to us an article in the U.K.’s Daily Mail, where a teenager from Nepal had managed to create a 9v, 18W solar panel using human hair rather than the usual semiconductors (usually crystalline-silicon). The complex silicon in solar panels are what keep the prices out of reach of developing nations, and while there are a number of new technologies that are helping bring down the cost, [Karki] managed to make his solar panel for only £23 (roughly $38). He also claims that when mass produced the price could drop substantially down to under $10 a panel, which would shatter the $1/watt sweet spot.

The melanin in hair acts as an organic-semiconductor, and while the hair does not have the longevity that silicon panels have (months rather than years), these panels can be made cheaply and serviced with little to no complex knowledge. Using melanin as an organic semiconductor seems to be a newer idea, because information seems hard to come by, but we managed to find a research paper from 2007 that explored the energy absorption attributes of melanin, as well as some good background info for the science types.

Research Paper (Warning: PDF)

So, Hack a Day readers, which one of you is going to make your home-brew solar panels first? Let us know when you do.

Thanks [unangst].

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