Photovoltaic Revolution: Changes in Solar Farm Technology and Construction Methods 2

Table of Contents

Introduction3 A Brief History of CSP and Photovoltaic Solar Power4 Concentrated Solar Power (CSP) ...... 4 Photovoltaic (PV) Solar Panels...... 5

Market Demand for Photovoltaic and a $1 Billion CSP Solar Farm Failure6 The Failure of Crescent Dunes...... 6

The Future of Solar Farm Construction in the U.S.8 Future Innovations in Solar Farm Technology10 Greater Storage Capacity for PV...... 10 Floating Solar Farms...... 10

Conclusion12

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Introduction

Solar energy, among the fastest-growing renewable energy sources in the world, accounted for 1.7% of the world's energy supply by the end of 2019. In the U.S. 11% of the country has adopted solar energy in some form with a nearly50% annual growth rate over the past decade.

The push for solar means more utilities are adding the renewable energy to municipal grids, which in turn creates the need for solar farms as well as innovations dedicated to making such installations as efficient and cost- effective as possible. Over the past decade photovoltaic (PV) panels have skyrocketed in popularity as a preferred technology due to the plummeting price of solar panels; however concentrated solar power (CSP) offers benefits they may be more valuable than photovoltaic’s upfront price tag.

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A Brief History of CSP and Photovoltaic Solar Power

Concentrated Solar Power (CSP)

CSP uses lenses or mirrors to concentrate sunlight into a narrow beam that heats a fluid, producing steam to drive a turbine that generates electricity. The oldest presumed use of harnessed solar energy involved CSP and stems from Greek A CSP farm uses mirrors to concentrate solar power. warfare.

The mathematician and inventor Archimedes is said to have used concentrated solar power as a naval defense against Roman warships. By situating large copper mirrors on a cliff, soldiers directed thermal energy onto incoming vessels, thus setting them alight. The validity of this account has been debated and tested by various scientists over the centuries, and while many agree that parabolic mirror technology existed in Archimedes time, no conclusive evidence exists that this event actually took place.

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The first scientifically documented use of CSP occurred in 1866when French inventor Augustin Mouchot used a similar mirror technology to heat water for powering a steam engine. His technique would continue to be expanded upon by peers and colleagues, culminating in the founding of the Italian Archimede Solar plant nearly a hundred years later. The first CSP-based solar farm in the U.S. would be established inthe state of California 14 years later in 1982.

Photovoltaic (PV) Solar Panels

Photovoltaic is the conversion of sunlight into energy using a semiconductor material to charge electrons. Modern PV technology primarily uses silicon as a semiconductor in solar panels.

The first solar cells that would later be the framework for modern solar panels were developed in the early 19th century by German inventor Charles Fritz. While their energy conversion capabilities were too low to be of any significance, Fritz’s work inspired future scientists and engineers to continue to build upon the technology.

More than a century after Fritz’s creation, Bell Labs created the first silicon solar panel in the 1950s. The silicon panel was only 6% effective at converting solar energy into electricity but it was a vast improvement over Charles Fritz’s selenium-based design. Today, PV solar panels can reach 20% effectiveness when converting sunlight into energy and are affordable enough for average consumers to have installed ontheir rooftops.

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Market Demand for Photovoltaic and a $1 Billion CSP Solar Farm Failure

Current market demand The failure of the Crescent favors photovoltaic Dunes CSP project would technology over CSP mostly foreshadow the decline of based on equipment cost. For consumer markets, its CSP in the U.S. market. low cost makes it highly attractive. For large installations, many solar energy projects are backed by investor funding and investors are driven to secure a high return on investment. In the pursuit of the highest possible returns, they will often choose the lowest cost equipment.

While PV technology is relatively cheaper in comparison to CSP, it does not mean it is the most effective or efficient for every solar farm project. For example, CSP is capable of storing energy via TES (thermal energy storage) for use during off-peak hours. PV systems in comparison depend primarily on lithium-ion battery storage which when compared to TES, is extremely limited in storage capacity.

The Failure of Crescent Dunes

In 2011 a $1 billion CSP solar energy plant was built in the Crescent Dunes near Tonopah, Nevada. The project was the United States’ most

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ambitious government-supported solar energy project of its time. It failed due to mismanagement of funds and a general underestimation of upkeep costs. As an example, when a steam generator failed, it required custom parts to be ordered. It also soon became apparent that maintenance needs where high. The Crescent Dunes plant staffed dozens of workers to handle the steam engine's constant repair. By the schedule date for the plant to go online arrived, it had already been defunded as a cost-cutting measure.

Another nail in the coffin for the project was the rapid advancement of cheaper PV technology which had overtaken the market within the short period the plant was being constructed. Though CSP offers greater efficiency in the long run due to its superior energy storage capacity, pressure to cut costs upfront made PV more attractive to investors and the public sector.

The Crescent Dunes solar energy project in Nevada.

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The Future of Solar Farm Construction in the U.S.

Despite CSP technology’s apparent advantage over photovoltaic systems when it comes to storage (16 hours of dispatchable power compared to two to four hours for PV) it appears destined to disappear from the Photovoltaic solar farms now dominate the market. U.S. market. Considering that much of modern CSP technology was pioneered in the United States, that idea is somewhat ironic.

While Crescent Dunes is perhaps the most infamous failure of a CSP plant, other plants around the country have also faced troubles. Unable to compete with the dramatically falling price of PV solar panel systems and the comparable speed at which a PV solar power plant can be constructed, many CSP projects have either been abandoned or have converted to PV.

A few examples include:

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● The Blythe Solar Power Project which converted to photovoltaic. ● The Rice Solar Energy Project which has been on indefinite hold since 2014. ● The Hidden Hills Solar Project which was suspended in 2013 and later canceled.

Crescent Dunes along with the highly attractive cheaper cost PV have had a highly detrimental, long-lasting effect on CSP in this country. To date, no major CSP plants remain under construction in the United States.

In comparison, the number of large-scale PV projects projected to be constructed is expected to reach 32 in 2021. Despite CSP falling out favor in the U.S. there appears to be a growing interest in the technology in Asia, which could potentially bode well forBrightSource Energy, the United States’ last remaining CSP developer.

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Future Innovations in Solar Farm Technology

Greater Storage Capacity for PV

Despite the attractive While photovoltaic’s price price tag that comes tag makes it attractive, its with PV solar it limited storage capacity is a continues to have one glaring drawback: problems that needs solving. storage limitations. Venture-backed Form Energy recently deployed a long-duration battery designed for use with utility grids which boasts the ability to deliver 1 megawatt of power over 150 hours. This delivery window far exceeds that of lithium-ion batteries currently utilized for most large-scale solar projects. If successful, the batteries may be the key to fully unlocking the potential of photovoltaic as a preferred solar energy system.

Floating Solar Farms

There is a more water than land on planet earth, and the process for securing the acreage required for solar farms can be challenging. Despite solar energy’s branding as an environmentally friendly energy choice, the vastness of solar arrays can be fairly disruptive to the surrounding landscape.

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Other issues arise when land needs to prioritized for housing and other human activity, or if a community simply doesn’t want the visual dominance of a solar farm in their vicinity. In such instances, open water offers a less contentious option.

In 2007 Japan pioneered the firstfloating Photovoltaic solar farm, a grid- connected hybrid system utilizing floating solar panels and hydropower plants and the concept was subsequently adopted by California. China has since developed the Huainan Farm constructed in Anhui Province which as of this writing is the largest floating solar farm in the world.

Floating solar farm in Anhui Province, China.

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Conclusion

Solar energy has rapidly gained market share around the world. The technology for solar farm construction has evolved in tandem with market demand, designating photovoltaic as the apparent winner due to its comparatively cheap startup and maintenance costs. PV’s largest remaining obstacle appears to be poised to fall as new breakthroughs in battery storage technology look to dramatically increase the dispatchability and continuity of PV-derived solar energy.

This paper was authored by the Energy Education & Research Institute, a foundation committed to promoting energy conservation through education, research and innovation. We believe in insightful and impact- oriented research that hinges on diverse people and practitioners working together to research and address complex problems and opportunities at the intersections of energy, innovation, and society.

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