Until now, we’ve made solar panels from silicon for a very important reason: It’s fairly easy to work with. Silicon is essentially highly processed sand. It has helped affluent areas in the industrialized world advance solar panel adoption at an impressive rate.
In fact, in many regions, “traditional” silicon-based solar panels offer utility rates that are competitive with, and sometimes lower than, incumbent energy providers that rely on fossil fuels.
Our reliance on silicon for solar panel manufacturing has come with a tradeoff, however. This type of solar panel is heavy, not especially portable and is somewhat brittle. These factors do not make ordinary solar panels an ideal choice in some of the harsher climates or in some of the remoter areas of the developing world.
The latter might include villages that require electricity to power small community businesses or keep their water pumps operational.
The attractiveness of the sun as an energy source for developed and developing nations alike is clear by now — but there is also a very real need for a more durable and literally flexible solar panel material. Researchers think they’ve found the answer in a design they’re calling a “solar tarp.”
How Did the Solar Tarp Design Come About?
Lipomi Research Group is a pioneer of solar tarp concepts that stand good chances of reaching the market, although they’re quick to point out they’re drawing from an existing foundation of published scientific research. Their mission was to build a durable, light and flexible solar “panel” that could realistically perform the same duty, with the same output, as a silicon-based panel.
They’ve proposed a solution to that mission in the form of a flexible solar tarp that can fold down as small as a grapefruit, but still unfurls to the same surface area as the footprint of a small room.
Thinness alone wasn’t the focus of this project. In fact, the engineering going on here is happening at the molecular level. Regular solar panels can’t bend, to say nothing of getting folded and stowed in a knapsack, but the research group’s proposed device could experience up to 1,000 folds before its integrity gets compromised.
Until now, chemical-based materials research was satisfied with silicon as the best semiconductor for solar panels because it stood effectively alone in being cheap, but could also convert the energy in light to usable forms. Thinness and ultimate portability were problems for another day.
But we’ve reached a bottleneck in terms of how widely silicon solar panels can proliferate into the developing world, where easy transportation and durability are primary concerns for technology adoption. Silicon is going to need an upgrade — or we’re going to need an entirely new type of molecular engineering — if the future is indeed flexible electronics and solar panels.
By experimenting with chains of molecules, researchers can create brand-new families of materials, and some of them make brilliant semiconductors. One type, called “perovskites,” are just about as efficient as silicon at one-thousandth the thickness. In other words, many factors in material engineering determine whether the sun’s energy gets absorbed and put to work, or reflected and re-emitted. Some of them are superficial, like the color of metal roofing. But when it comes to solar roofs and solar panels, which must absorb and convert solar energy rather than turning it away, it takes entirely different chemistry.
Some of the building blocks have been there for years, it turns out.
In 2000, the Nobel Prize for excellence in chemistry went to a team that proposed a so-called “organic semiconductor” — a carbon-based chain of organic polymers — that went on to realize widespread commercial adoption as the underlying technology in OLED television screens, mobile displays and monitors.
Polymers show some promise as very durable semiconductors for solar panels, but without the efficiency of perovskites.
The scientists and researchers at Lipomi Research Group — and elsewhere, almost certainly — want to find that so-far elusive balance between the durability of plastics, with a foldability even greater than tarp canvas and the semiconducting efficiency of silicon. Or, ideally, greater than silicon.
Under laboratory conditions, perovskites have demonstrated an electricity-converting efficiency of 26 percent. Scientists believe 29 percent is the “maximum” theoretical efficiency limit for silicon semiconductors. But, again, even if we reach that point, we have the brittleness and heaviness of silicon panels to contend with.
A Promising Start With Lots of Potential Applications
Given the physics and chemistry involved, our accumulated scientific research seems to point to flexible solar panels and tarps based on perovskite semiconductors as the obvious next step in the evolution of the world’s solar infrastructure.
If scientists can find a scalable manufacturing process that can turn out such a semiconductor, with an efficiency almost as good as silicon’s, the applications go far beyond commercial and residential rooftops.
When this material comes of age, we could use it to develop indoor and outdoor solar floor tiles, solar blankets and clothing, vehicle skins, new types of road surfaces and power-generating parking lot paving materials.
Written by Kayla Matthews, Productivity Bytes.