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Published on November 30th, 2018 | by Charles W. Thurston


EVs, Aerospace, & Wearable Solar Foster Power-to-Weight Advances

November 30th, 2018 by  

Advances in thin-film and other new solar technologies are expected to be driven by the demand for lightweight, high-power solutions in the EV, aerospace and wearable solar markets, reckons Matthew Reese, the author of a new study on the evolution of the technology.

Two other non-standard PV markets—microscale integrated PV and building integrated PV (BIPV) could also help drive the market for PV with with high power-to-weight ratios.

“Each of these nascent markets approaches or exceeds gigawatt- scale cumulative potential in the next decade with projected prices exceeding $1 per Watt,” says Reese, a physics researcher at the National Renewable Energy Laboratory, in Golden, Colo.

Within photovoltaic research, thin-film and emerging technologies like perovskite-based cells offer advantages for lightweight, flexible power over the rigid silicon panels that dominate the present market, says Reece.

Unfortunately, billions of dollars are needed to pursue each of the specific lightweight, high-power chemistries in solar development, and the market demand that is expected to be necessary to help drive down manufacturing costs will also far exceed the multi-billion-dollar level, Reese says.

He and eight other co-authors wrote the study, “Increasing markets and decreasing package weight for high-specific-power photovoltaics,” which was first printed in nature.com, and funded by the U.S. Office of Naval Research and was supported by the U.S. Department of Energy.

One way that sales of solar products could rise more quickly is to engage non-solar companies in the sale of specialized lightweight, high-power products. The drones, EV, and general building industries are examples of such potential cross-selling, Reese points out. Similarly, governmental policies mandating zero-net-energy buildings, and fleet fuel economy standards may speed up adoption, he adds.

One reason for U.S. military interest in lightweight, high-power solar products is that soldiers on the ground carry heavy loads of gear, within which batteries represent significant weight. Wearable and rollable solar cells could replace much of the demand for batteries by soldiers and other military, which would benefit from the ability to move more men and material faster.

“Significant system weight reduction generally results in improved flexibility, so both added-value propositions can be quantified in terms of specific power or watts per kilogram,” writes Reese. Although early work in the PV industry has focused on maximizing specific power by using the highest-efficiency solar cells, cell substrates and encapsulation packaging are often poorly understood or overlooked opportunities for maximizing specific power, form factor and flexibility, he points out.

Non-Standard Markets with the Greatest Demand for Lightweight, High-Power Solar

Aerospace and UAVs

Aerospace is the highest price-point market with requirements of high specific power and high efficiencies owing to limited surface area. This market primarily consists of satellites and UAVs, because PV has insufficient power density to support most manned aircraft, the researchers observe.

PV adds value through the ability to increase range and flight duration, but products have reduced life expectancies. And while there is reduced susceptibility to moisture and oxygen, radiation hardness is a significant concern, the researchers say. Depending on orbit, satellites can stay in orbit for as little as a year to as long as 15 years, the authors say.

Public statements and cost modeling have indicated that costs are likely to fall costs over the next decade, Reese and company say.

Portable Charging

General requirements for portable charging include rapid module deployment and relocation by one person without complex wiring, mounting or delicate handling requirements. In this market, the need for high specific power, efficiency and flexibility that enables rapid person-portable deployment must be balanced with cost, the researchers say.

“Reaching the correct balance could facilitate millions of units to be utilized in disaster relief, military and recreation applications. Module power requirements are similar for these markets,” the researchers say. “This provides a moderately high-value market for such specialized products, with outdoor lifetimes in the range of one to three years. However, these products must be rugged and withstand numerous deployments or relocations from non-experts with rough handling,” they say.

Vehicle integration

Vehicle manufacturers are more cost-conscious than the previous two markets, the researchers note. PV installed on a vehicle will compete at least indirectly with grid-supplied electricity. However, PV provides additional benefits in terms of ambient temperature control and modest range extension. This is estimated to be up to 13–24 miles per day during Arizona summers for varying vehicle sizes, they point out.

Lifetime requirements are limited to that of the vehicle or about 10 years or 250,000 miles, the researchers say. The total ground transportation market potential is large with 100 million vehicles per year predicted to be sold globally in 2020. PV installed on vehicles may utilize smaller panels than utility-scale PV, need to conform to roof contours, and require different wiring and power electronics. This suggests that flexible products may have an advantage in this market, they say.

The 2015 plug-in hybrid and battery electric vehicle market size was 1.26 million, doubling globally from 2014 to 2016, the researchers estimate. “Assuming at least 5% of such vehicles integrate 100 Watts each, that would lead to a present-day market size about 10 MW,” they say. Within a few years, the cumulative market worth will exceed $1 billion, they predict. 


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About the Author

Charles specializes in renewable energy, from finance to technological processes. Among key areas of focus are bifacial panels and solar tracking. He has been active in the industry for over 25 years, living and working in locations ranging from Brazil to Papua New Guinea.

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