Solar Photovoltaic Power Optimization

Enhancing System Performance through Operations, Measurement, and Verification

Michael Ginsberg

• Publisher: Routledge
• Year: 2019
• Print ISBN: 9780815398592
• eBook ISBN: 9781351172028
• Topic: Biological Sciences
• Subtopic: Ecology
• Index: Biological Sciences

This book focuses on the rapidly maturing solar photovoltaic (PV) industry, which is achieving an ever-increasing share of U.S. and global power production.

There is a growing need for all stakeholders – owners, maintenance technicians, utilities, and installers – to fully understand the operations and maintenance of PV systems, and how to monitor and diagnose systems post installation. Recognizing this need, this book covers monitoring and diagnostic techniques and technologies, including how to identify the causes of poor performance, and measure and verify power production. Drawing on global case studies, it details how to achieve optimal PV power output in the field through an overview of basic electrical, the solar PV module and Balance of System, and processes and software for monitoring, measurement, and verification. It also provides an overview of the North American Board of Certified Energy Practitioner's (NABCEP) new PV System Inspector credential, which will be outlined in the final chapter.

Equipping the reader with the knowledge and confidence required to maximize the output of solar PV installations, Solar Photovoltaics Power Optimization will be an essential resource for PV practitioners and students.

1 The need for solar photovoltaic system operations and maintenance, and measurement and verification

History of the solar photovoltaic industry

The solar photovoltaic (PV) industry evolved in three stages. First, the fundamental science underpinning the industry was established in the 1800s and early 1900s. Next, the silicon PV cell was developed in the 1950s. Finally, low-cost manufacturing methods enabled solar PV to achieve grid parity, or cost equivalence, with conventional fossil fuel generators, making it a viable choice for investors and energy consumers today.

Stage 1: establishing the science

In 1839, 19-year-old Alexandre Edmond Becquerel, who later went on to become a world-famous French physicist, constructed the world’s first PV cell. The cell used silver chloride in a liquid acid solution and produced an electric current when light was shone on it, a reaction which is sometimes called the “Becquerel effect.” In 1876, William Grylls Adams and Richard Evans Day discovered that the PV effect could be produced in a solid, namely, solidified selenium. Soon after, in 1883, American inventor Charles Fritts coated selenium with a layer of gold, which achieved a power conversion efficiency of 1–2%.¹ In 1905, Albert Einstein published a seminal paper on the photoelectric effect using quantum theory. Eleven years later, Robert Millikan’s experiments demonstrated the validity of Einstein’s theory. This led to Einstein winning the Nobel Prize in Physics in 1921 “for his discovery of the law of the photoelectric effect.”²

Stage 2: developing the silicon PV cell

In the early 1950s, Daryl Chapin, Calvin S. Fuller, and Gerald Pearson at Bell Laboratories developed the first modern solar PV cell using silicon (with 4% efficiency; they later achieved 11%).³ On April 25, 1954 in Murray Hill, New Jersey, they demonstrated their silicon solar module by using it to power a toy Ferris wheel and a radio transmitter. The first practical use of the technology was to power satellites in space, starting in 1958 with the Vanguard I, which used a small array (less than one watt) for its radios.⁴

Stage 3: low-cost manufacturing

As shown in Figure 1.1, the unit price of a solar cell fell over time. In the 1970s, Dr. Elliot Berman, with help from Exxon Corporation, designed a production process that sharply reduced costs, slashing the price from $100 per watt to around $20 per watt. New practical uses were found for the silicon PV cell, such as powering remote sensors and navigation lights on offshore oil rigs. In 1973, the University of Delaware showed that solar energy could power a house. In 1978, NASA installed the first community PV system, which supplied electricity to 15 homes in the isolated Papago Indian Reservation in Arizona for water pumping and residential needs.

Solar energy took another major step forward in the early 1980s when the oil company Arco Solar built the first large-scale solar park in Hesperia, California, near Los Angeles. Opened in 1982, this solar park generated 1 megawatt, or 1,000 kilowatts, supplying the Pacific Gas & Electric (PG&E) Company with enough power for 2,000–2,500 homes. Until this point, the industry had only achieved 15% efficiency in harnessing energy from sunlight. However, this changed in 1992 when the University of South Florida unveiled a 15.9% efficient thin-film PV cell made of cadmium telluride.⁵ In the 1990s, as cell efficiencies rose and manufacturing costs declined, utilities began to take interest in PV systems. PG&E became the first U.S. utility to operate a large-scale PV system, a 500 kW array in Kerman, California. The early 2000s saw a rise in grid-tie systems for residential and commercial customers, and, as shown in Figure 1.2, by 2012 solar reached grid parity with conventional fuels.

Figure 1.1The progression of manufacturing of solar PV cells from the 1970s to today.

Source: Author.

Figure 1.2Achieving grid parity – solar PV’s rapid cost decline beginning in 2009 and current cost equivalence with conventional sources (price in $/mmbtu).

Source: Michael Parker and Flora Change, Bernstein. Data from EIA, CIA, World Bank.

By 2016, solar cells could be manufactured as thin as paper using an industrial printer and with 20% efficiency, and a single strip could produce up to 50 watts per square meter.⁶ Figure 1.3 shows the dramatic cost reduction achieved in PV materials and manufacturing, yet soft costs remain high.

Figure 1.3Q4 2018 installed PV prices in the U.S. by system size. The figure on the top shows that soft costs comprise 65% of residential installation cost. The figure on the bottom shows that economies of scale enable lower prices for commercial and utility-scale systems.

Source: Harness It: Renewable Energy Technologies and Project Development Models Transforming the Grid by Michael Ginsberg.

Data from Wood Mackenzie, Limited/SEIA U.S. Solar Market Insight Q4/2018^®.

As of Q1 2018, the U.S. has 55.9 GW of total installed capacity, with 18% of all electricity in the U.S. coming from renewable sources and most new capacity from solar.⁷

Figure 1.4Table showing the number of units and installed capacity of different energy sources in the U.S. installed in Q1 2018 vs Q1 2017. Solar was the third leading source of new capacity in the U.S. in 2018.

Source: Office of Energy Projects Energy Infrastructure Update for December 2018, Federal Energy Regulatory Commission.^8,9

The importance of O+M and M+V

The rapid deployment of solar energy, both PV and concentrating solar power (CSP), has led to a correspondingly swift increase in employment in the sector. The number of employees who spent a portion of their time working on solar energy rose from 93,000 in 2010 to almost 350,000 in 2017 – about 250,000 (or 70%) of whom spent at least half of their time supporting the solar portion of their business.¹⁰ This rate of growth is more than nine times faster than employment growth in the overall U.S. economy.¹¹

In 2017, solar energy workers represented about 40% of the total electric power generation workforce, which is more than the combined number of workers with fossil fuels (gas, coal, and oil) in electricity generation.¹² While the heaviest concentrations of jobs in the U.S. are in California, Massachusetts, New York, Texas, Florida, and Arizona, employment is expanding rapidly throughout the U.S.¹³

Figure 1.5Solar jobs in the U.S. were the second highest of all energy segments in the U.S. in 2016.

Source: Bloomberg New Energy Finance.

This trend is not limited to the U.S. Solar is emerging globally as one of the leading new sources of jobs. The International Renewable Energy Agency (IRENA) estimates the solar PV industry accounts for nearly 3.4 million jobs worldwide.¹⁴

Unlike fuel generators that require weekly or even daily maintenance, once installed, silent PV systems can be easy to forget. Aside from trackers, they are comprised of steady-state devices with no moving parts. However, PV O+M and M+V i...

Table of contents

• Cover
• Half Title
• Title
• Copyright
• Dedication
• Contents
• Acknowledgments
• Preface
• 1 The need for solar photovoltaic system operations and maintenance, and measurement and verification
• 2 Electricity and solar cell and system fundamentals
• 3 Tools and methodology for maintenance and troubleshooting
• 4 Tools and methodology for monitoring, measurement, and verification
• 5 Conclusion: the growing market for PV system inspectors
• Glossary
• Index