Solar Materials and Efficiency Improvements Are Transforming the Business of Power Generation

August 5, 2019 – From the desk of Peter Diamandis comes this latest missive on the current state of solar energy. I have taken the liberty to edit, annotate, and add to Diamandis’ words, I believe, to better make his points.

Diamandis notes that solar panels have been with us for several decades, but that the uptake of the technology has been less than stellar considering the scientific evidence that shows us that reliance on fossil fuels for power generation is making climate change an existential problem.

You would think sunlight, such a ubiquitous source of power, would, therefore, be the way the world should be going. Yet based on 2015 data, only 1% of global electricity was being produced on our planet from solar energy sources.

Is this about to change? Diamandis says so and sees an abundance of solar in our future. 

Every five days, the Sun provides Earth with as much energy as all the supplies of oil, coal and natural gas ever found. Capturing just one 6,000th of the Sun’s energy would meet 100% of the world’s current requirements.

We are currently riding a wave of advancements in both solar panel efficiency and novel methods of expanding surface area coverage. The cost of solar energy continues to plummet with the price per watt averaging around $3.00 USD this year. While the efficiency of current run-of-the-mill solar panels still hovers around 16-18%, half of their theoretical efficiency potential, new materials science breakthroughs are now on track to double that number, promising cheap, efficient and abundant solar energy. Expect the price-performance ratio of solar technologies to further undercut traditional energy sources, and with this we will see mass integration of solar cells into everyday infrastructure.

The Surge of Solar-Capturing Surfaces

Current solar energy-generating plants tend to be deployed on swaths of out-of-eyesight farmland, or on roofs of off-the-grid homes and commercial properties. Critics point to land area use as the single greatest barrier to widespread solar adoption. But this is a fallacy. Expect in the next decade solar panels to be installed ubiquitously across urban and semi-urban areas, embedded in infrastructure, on transparent surfaces and even on vehicles. Even now, there are tens of thousands of acres of urban space available for solar deployment, and that is not taking into consideration soon-to-be-repurposed parking lots once driverless vehicle fleets proliferate.

The product is also evolving to improve the aesthetics as well as efficiency. Imagine if every window and glass surface could become a solar energy source. Well, new advancements in transparent solar panels are bring this future to fruition. Five years ago, transparent solar panels (or solar cells embedded in transparent surfaces) were incapable of harnessing enough energy to justify cost and commercialization. In 2013, efficiency stood between 1 and 3%. What’s more, the opacity of these clear surfaces was still far too high, limiting light penetration. That’s not the case today with solar cells and solar capture materials finally becoming sufficiently versatile to be integrated into glass and other aesthetic surfaces.

Ubiquitous Energy, a Silicon Valley startup, which raised $22.8 million USD to date, has developed a transparent solar cell called ClearView Power, achieving 9.8% efficiency. A color-neutral coating that can be put on a glass surface, ClearView Power’s technology can absorb and convert non-visible light (ultraviolet and infrared) into electricity. It theoretically can be applied to any window of an existing building without obstructing visible light. Ubiquitous has nearly doubled glass solar panel efficiency in one year after researchers at Michigan State University announced they had invented a similar panel with 5% efficiency in 2018.

What can this mean for solar energy deployment? Within the next decade, we should see commercialized solar-capturing glass populating every skyscraper, school, and residential rooftop, generating abundant and newly democratized energy.

Solar technology is also making improvements in the non-transparent category as well. Numerous startups are tackling solar tiles and solar roofing technologies, aiming to integrate them seamlessly into the construction of homes and mid-scale structures.

Tesla has its own brand of beautifully designed solar tiles called Solar Roof. The Tesla roof incorporates an embedded Powerwall battery along with highly durable solar shingles that both convert and store solar energy throughout the day and make it available at any time. Amenable even to customized levels of electricity generation (based on household energy usage), Tesla’s Solar Roof essentially converts any home into its own utility. Elon Musk recently stated, “We have a shot at being equal to a comp shingle roof plus someone’s utility cost or being lower than that. That’s one of the cheapest roofs available. So you can have a great roof with better economics than a normal fairly cheap roof and your utility bill.”

Projecting a future wherein residential structures not only fuel your household activities but can make you money, Musk believes that solar roofs will cost less than traditional roofing materials (already at near-zero maintenance costs) in just the near future. Not only that, but current figures (see image and chart below) would suggest that solar shingles can compete on price with rooftop installation of traditional solar panels:

Price Comparison of Solar Roof and Premium Roof + Solar Panels. Source: Electrek.

Tesla is not alone in the solar roof game. Forward Solar Roofing, a Silicon Valley-based startup, claims to have already undercut the price of Tesla’s product by half with its own solar roof. The company’s first batch of pre-ordered roofs sold out within a week, and while it remains unclear if the company will be able to deliver, current figures tout an energy density of 19 watts per square foot. Forward also incorporates a venting system to offset efficiency loss through solar panel overheating.

Materials and Efficiency

Historically, inefficient electrical production has stood as the greatest barrier to large-scale solar adoption. Yet the efficiency of photovoltaic cells has improved exponentially since their invention with today’s panels averaging 18% efficiency, meaning they capture 18% of the solar energy to which they are exposed.

Solar Panel Efficiency Improvements, 1960 – 2017. Source: Go Solar Texas.

But 18% is no longer the limit as can be seen in the graph depicted above. Several companies including Solar City, Panasonic, and SunPower have achieved solar panels with 22-23% percent efficiency, a 25% efficiency increase from what is being deployed currently.

SunPower, the $1.5 billion USD public company boasts the X22 solar panel reaching 22.8% efficiency. Tesla and Panasonic (jointly engaged in producing solar cells) have broken the 20% efficiency threshold in their commercial products.

In terms of price-performance, the gross cost of solar panels per watt has fallen a staggering 64% since 2014 (in just 5 years).

But even these improvements are being challenged by new innovations borne out of research and development laboratories. For example, the National Renewable Energy Laboratory and Swiss Center for Electronics and Microtechnology announced in 2016 that they had built a solar cell capable of 30% efficiency. A year later, scientists from George Washington University and the Naval Research Laboratory announced a cell capable of 44.5% efficiency.

SolSunTech, a New York City startup has achieved 33% solar panel efficiency in its first few years of operation. The company uses three-dimensional panels as opposed to the flat panels we are used to seeing. The three-dimensional silicon wafer structure significantly increases solar-absorbing surface areas. Its wavy shape further allows re-absorption of reflected light. A simple engineering solution, SolSunTech now plans to begin construction of a 100 Megawatt/hour facility in December of 2019 following the company’s next financing round.

And then there is perovskite, a naturally occurring light-sensitive crystal that is seen as the next breakthrough in solar energy. In the past five years, the conversion efficiency of perovskite-solar panels has increased from 4 to 23%, making it the fastest-developing material technology in photovoltaic history. The theoretical upper limit of perovskite is seen at about 66% which is more than twice the current upper limit for silicon-based photovoltaics. Perovskite is also widely available and inexpensive to extract and use. Estimates suggest perovskite panels will cost between 10 and 20 cents per watt, compared to 75 cents (or almost four times the cost) of the panels we are producing today. Scientists are adding a chemical compound, guanidinium thiocyanate, to perovskite films to make them more adaptable to all kinds of uses and application surfaces. The thinness of perovskite films, its flexibility, and low weight, means it can be installed on flat, curved, sinuous, or other types of surfaces. That is not the case for silicon-based panels. Most recently, a new startup, Perovskite PV, secured $2.4 million USD in seed funding. Others will soon follow.

But don’t count silicon-based photovoltaics out. Researchers recently found a material defect in silicon responsible for a 2% drop in efficiency that panels experience in their first few hours of use. As solar cells’ electronic charge is transformed in the presence of sunlight, the flow of electrons gets trapped. This, in turn, reduces the level of electrical power that can be produced. While seemingly negligible, the potential to recapture this 2% efficiency from light-induced degradation (LID) represents an opportunity to increase the efficiency of existing solar panels globally, equal to more energy than what the United Kingdom’s 15 nuclear power plants produce today.

Final Thoughts

Advancements in materials science, battery storage, and solar-capturing surfaces are driving a future of solar energy abundance. According to a recent Harvard study, solar energy cost decreases will drive a 700% growth in solar power production over the next 20 years. That’s on top of the 2,000% growth in U.S. solar power generation in the last nine. In 2015, U.S. solar power amounted to 7% of all renewable energy power generation in the country. That number is expected to top 36% in 2050 which will make it the fastest-growing energy source in the United States by that date.