The 6000 Year Story of Solar Energy

8/10/2019 The 6000 Year Story of Solar Energy

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Let It Shine:

The 6000 Year Story of Solar Energy

By John Perlin

With a Foreword by Amory Lovins

The New and Expanded Edition

Copyright 2013 John Perlin

Chapter Descriptions

I. Early Use of the Sun

Chapter 1: Solar Architecture in Ancient China (6000 BC -)

Six thousand years ago Neolithic Chinese villagers had the sole opening of their homes face south. They did thto catch the rays of the low winter sun to help warm the interior. The overhanging thatched roof kept the high

summer sun off the houses throughout the day so those inside would stay cool. Two thousand years later th

Chinese began to formally study the movement of the sun throughout the year in relationship to the earth

Knowledge gained from these studies stimulated Chinese urban planners to construct the main streets of town

to run east to west to allow every house to look to the south to catch the winter sun for supplementary heating

Over the millennia Chinese cities followed such planning and still today the Chinese favor a south-facing home.

Chapter 2: Solar Architecture in Ancient Greece (500 BC-100 BC)

Socrates was outspoken about the value of building with the sun in mind for the comfort of the occupants

Aristotle also taught his students the value of designing houses to make maximum use of the winter sun and t

keep the house in shade during the hotter months. Archaeological digs have confirmed that the ancient Gree

builders followed the advice of these sages. Retrofits in Athens followed by whole cities such as Olynthus

Priene, Delos and many others, as well as rural dwellings, show that solar architecture became ubiquitous in

Greece and its surroundings for centuries.

Chapter 3: Roman Solar Architecture (100 BC-500 AD)

Romes greatest architect Vitruvius saw solar houses while on duty as a military engineer in recently conquered

Greece. When writing his great work On Architecture, he emphasized proper solar orientation for buildings an

bath houses. From literature of the time it appears many followed Vitruvius instructions. Baths were especially

popular among the Romans but demanded a great amount of heat. From the times of the early empire onward

most faced the afternoon sun in wintertime when they had maximum use. They also had their large windows

covered with either transparent stone like mica or clear glass, a Roman invention of the 1st century ACE, one o

the great breakthroughs in building and solar technology. Transparent materials like mica or glass, the Roman


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discovered, acts as a solar heat trap, admitting sunlight into the desired space and holding in the heat so

accumulates inside. Facing structures to the winter sun became so popular in Roman times that sun-right laws

were passed, making it a civil offense to block ones access to the south.

Chapter 4: Burning Mirrors (1000 BC-1800)

Three thousand years ago the Chinese discovered how to make concave reflectors to turn sunlight into fire

Many centuries later, around the 5th century BCE, the Greeks independently developed such solar devices. Botused them to kindle wood for cooking. When natural scientists of the renaissance learned of these inventions

many envisioned using them as the ultimate weapon, burning whole armies and fleets with concentrated power o

the sun. The sketch books of Leonardo show that the great Italian technologist had great solar ambitions to us

concave mirrors for industrial heating. People from London to Paris watched in awe as experimenter

concentrated rays of the sun to melt metals and vitrify glass in seconds.

Chapter 5: Heat for Horticulture (1500s-1800s)

With the decline of the Roman Empire, the use of transparent glass all but disappeared. Glass was not usedagain to trap solar heat until the wealthy citizens of the Age of Discovery wanted to enjoy oranges and other fruit

from Asia and the New World. South-facing greenhouses became popular to trap solar heat to encourage th

growth of such exotic plants in the colder climate of Europe, unduly frigid due to the advent of the Little Ice

Age. Sometimes a greenhouse was attached to the south-side of homes living room or library, transforming th

dull interior into a vibrant and warm space where people would congregate. On sunny winter days the doors

separating the greenhouse from the home were opened to allow sun-warmed air to circulate freely into th

formerly chilly interior.

Chapter 6: Solar Hot Boxes (1767-1800s)

The increased use of glass during the seventeenth and eighteenth centuries reawakened the awareness of it

ability to trap solar heat. In 1767, the Swiss polymath Horace B. de Saussure set out to determine how effectively

glass could trap solar heat. Saussure built a rectangular box from wood, insulated with black cork and its to

covered with glass. He placed a similar but smaller glass-covered box inside. When he tilted the box toward th

sun, the inner box rose above the boiling point of water. Because of the large amount of solar heat the device

retained, it became known as a Hot Box. The hot box became the prototype for solar thermal collectors used to

heat water and homes. Saussures hot boxes also modeled with amazing precision the dynamics of globa

warming with the glass acting as an atmosphere soaked with excess carbon dioxide stopping solar heat absorbed

by the earth from re-radiating into the sky.

II. Power From The Sun

Chapter 7: The First Solar Motors (1860-1880)

Alarmed by the prodigious amount of coal consumed as the industrial revolution moved forward, a Frenc


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mathematics professor, Augustine Mouchot, warned that Eventually industry will no longer find in Europe th

resources to satisfy its prodigious expansion. He then asked, What will industry do then? It must reap the ray

of the sun, the French professor concluded. Mouchot first studied what had already been done in times past to

put solar energy to use. His research led him to decide to build a concave mirror with a glass-covered boiler at its

focus. Exposed to the sun, it vaporized enough water to run the worlds first solar-powered steam engine. He

went on to construct even larger sun machines. In one experiment, he produced electricity, used it to separat

hydrogen and oxygen from water, and then store the hydrogen for fuel when the sun did not shine.

Chapter 8: Two American Pioneers (1872-1904)

The nineteenth-century Swedish-American engineer John Ericsson, well-known for inventing the iron-cla

battleship the Monitor which helped turn the tide of the Civil War in the Unions favor, believed that the sunny

areas of the world were the place for sun-driven motors. The application of the solar engine in these regions is

almost beyond computation while the source of its power is boundless. Ericsson wrote. In contrast, he feared

that the time will come when Europe must stop her mills for want of coal. The specter of collapse due to fue

shortages gave the inventor such a sense of urgency that he devoted the last two decades of his life to pursuin

the development of solar engines.

Aubrey Eneas actually installed three sun machines that ran irrigation pumps, all of them eventually in Arizona

The state had no indigenous fuel like wood or coal but it did have lots of sun so ranchers who needed to run

pumps looked seriously to solar as an alternative. Eneas recognized the market for his sun machine whos

height measured six stories and weighed four tons. Eneas exhibited his prototype at an ostrich farm in Pasadena

California where it pumped 1500 gallons of water per minute. One reporter predicted, If the sun motor will pum

water, it will also grind grain, saw lumber, and run electric cars.

Chapter 9: Low-Temperature Solar Motors (1885 - 1915)

Others interested in commercializing solar motors shied away from those concentrating the suns energy as too

complex and expensive to ever succeed. Charles Tellier, in 1885, came up with a very simple design. He angle

ten metal solar collectors against the outer wall of his workshop near Paris. He didnt try to produce steam from

water. Rather, he passed ammonia through them because of its lower boiling point. Even in a temperate climate

like France, the system worked well. Reading about Telliers work in the scientific journal Nature led tw

American engineers Henry Willsie and John Boyle to try to run a solar plant in Needles, California with anothe

fluid sulfur dioxide which also had a lower boiling point than water. To run their plant twenty-four hours a da

the engineers stored excess heated water in an insulated tank.

Chapter 10: The First Practical Solar Engine (1906-1914)

Frank Shuman, an entrepreneurial inventor, came up with an even more efficient design of a solar-concentratin

plant in 1912, consisting of long trough-shaped reflectors which focused sunlight onto glass-covered hea

absorbers through which water passed. For around seventy years the Shumans installation ranked as the larges


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solar power station ever constructed. Scientific American hailed it as thoroughly practical in every way.

III. Solar Water Heating

Chapter 11: The First Commercial Solar Water Heaters (1891-1911)

The first solar water heaters were just metal tanks left out in the sun. By late afternoon during summertime, they

held enough hot water with which people could shower. Clarence Kemp, a Baltimore manufacturer of heatinequipment, came up in 1891 with the idea of putting several cylindrical water tanks inside a hot box in 1891. A

solar heat accumulated in the box, water inside the tanks heated and remained hot longer than bare tank

exposed to the sun. Kemp called his invention the Climax. It has the distinction of being the first solar water sol

commercially. Its biggest success occurred in California during the end of the nineteenth century.

Chapter 12: Hot Water Day and Night (1909-1941)

Although the Climax Solar Water Heaters improved performance made them superior to bare tanks, people sti

had to wait for the sun-heated water to warm up in the morning as they cooled down at night with nothing morthan a sheet of glass between the heated tanks and the night air. William J. Bailey, an inventor living in a sunn

suburb of Los Angeles, noticed the problem. He solved it in 1909 by dividing the solar water heater into two

separate units the solar heat collector and hot water storage tank. Baileys solar heat collector, not tha

different from those used today, consisting of a shallow hot box containing water pipes soldered to a metal plat

painted black connected to a separate insulated storage vessel. Bailey called his product the Day and Night Sola

Water Heater as it provided consumers with steaming sun-heated water day and night. Between 1909 and the

early 1920s thousands were sold.

Chapter 13: A Flourishing Solar Industry 1923-1950

The solar water heater industry saw even greater success in Florida. Its expansion went hand-in-hand with th

building boom of the early twenties. By 1941, as many Miamians relied on the sun to heat their water as di

those using electricity, the only alternative. But war came, the government froze the non-military use of copper

the metal used for the piping and the heat absorber. Consequently, the industry came to an abrupt halt. After th

war, Florida Power and Light, the local utility, lured solar water heater owners to electric ones by offering them

large discounts and temporary reduced rates.

Chapter 14: Solar Water Heating Worldwide Part 1 (1930s-1960s)

Not every country had easy access to fuels like America. Israel in the 1950s had to ration electricity because

did not have enough generating capacity. Energy police enforced a ban on electric water heating the way mos

Israelis heated their water - during the day and evening so industry could continue to function. Levi Yissar, a

Israeli engineer, realized that solar water heaters much like those in Florida but adapted to the Israel climat

would allow people to have hot water twenty-four hours a day. The Israeli public bought tens of thousands. The

Japanese have always loved their hot baths. Those living in the low lands had little fuel. The Japanese saw the


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sun as their answer. By 1969 Japan had almost 4 million solar water heaters installed.

Chapter 15: Saving Airmen with the Sun (1943-)

The downing and rescue in 1943 of Ace Eddie Rickenbacker, Americas top pilot during World War I, led to the

invention of the first practical emergency solar desalinator. It was the experience of Eddie Rickenbacker drifting

on his little life raft, almost dying of thirst, solar scientist Dr. Maria Telkes recalled, that made her realize the

necessity of a source of fresh water for those men. She developed a practical compact solar desalinating kit sfuture airman cast adrift would go without fresh water. The design Dr. Telkes came up with adhered to the

principles discovered by Saussure. The Navy and Coast Guard made the Telkes solar desalinator standard fare

since, in the words of the military, drinking water is the most essential thing for those stranded in Pacific

waters.

IV. Solar House Heating

Chapter 16: Solar Building during the Enlightenment (1807-1850)

Dr. Bernhard Christoph Faust, the man responsible for reviving solar architecture in Europe in the early 19t

century, lived in a passive solar house built in 1649 in the tiny German town of Bueckeburg. After twenty years

there, he suddenly latched onto the idea in 1807 that all houses in Europe should open up to the midday sun a

his did. For the next forty years until his death Faust devoted his life to studying and proselytizing such buildin

principles. In 1817 he finished the manuscript to the first book entirely focused on a solar topic, entitled, All Me

Should Build Their Homes to the Midday Sun. His ideas would not have had much effect on the world had they

not piqued the interest of the very influential Bavarian state architect Gustav Vorherr. Thanks to Vorherr

relentless efforts, Bavarian and Prussian kings became the acolytes of Faust, mandating their subjects to build

schools and new homes according to the teachings of Faust. Urban planners reconstructing the burnt to th

ground city of Swiss city of La Chaux-de-Fonds based the work on a circular put out in 1834 by King Wilhelm

Fredrick of Prussia containing a blueprint for realizing a solar city according to Fausts idealized Sonnenstad

[Solar City] plan drawn up in 1807. The citys solar oriented streets and houses remain intact.

Chapter 17: Solar Architecture in Europe after Faust and Vorherr (1850-1939)

The slums of nineteenth-century industrial cities showed, in Fredrich Engels words, how little space a huma

being can move, how little air and such air! he can breathe, how little civilization he may share and yet live

For Engels only the overthrow of the capitalist class could change this horrid situation. Reformists in the late

nineteenth and early twentieth century had another answer - provide to the masses structures naturally warm

healthy, and illuminated based on solar building principles. No nation between the two world wars took on the

task more seriously than did the Germans. Functional building relying on the ideas of social justice and sola

orientation resulted in multiple apartment complexes oriented to take advantage of the sun in winter throughou

the urban centers of Germany. Similar housing spread to Holland, Sweden, and other northern European

countries. The rise of Hitler ended the solar architectural renaissance in Europe.


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Chapter 18: Solar Heating in Early America (1200-1912)

Native Americans in the southwest built, in many instances, according to solar design principles. North Americas

oldest continuously inhabited city Acoma serves as an excellent example with each unit tiered so ever

dwelling could catch the winter sun. William Atkinson, an early twentieth-century architect and urban planner

confirmed through scientific studies the wisdom of the builders of Acoma. By researching the apparent motion o

the sun and variations in the angles of sunlight at different seasons, Atkinson produced diagrams tha

demonstrated the amount solar penetration of building through differently oriented windows. He judged sout

windows as the best fenestration. Atkinson went further than his predecessors by measuring how much sola

heat each window orientation might trap in summer and winter. He did this by building a device he called a "su

box'' similar to de Saussures hot boxexcept that Atkinsons box was constructed to simulate a window and

room.The summer tests confirmed his hypothesis that east and west windows admitted too much summe

sunlight. The most spectacular results, however, occurred on December 22. The temperature of the south-facin

box rose to 1I4F, when it was only 24F outside, leading Atkinson to conclude, that if houses are properl

situated, "the sun's rays are not of indifferent value in the heating of our houses."

Chapter 19: An American Revival (1931-1950s)

The solar accomplishments in Germany and other European countries verified the value of building with the su

in mind. These studies began appearing in American architectural journals as well. Well-known Chicago architec

George Fred Keck was the first in America to apply their results in his design of homes in the Windy city and its

adjoining suburbs. In the late 1930s a Keck solar house warmed up so quickly one winter morning when the

outdoor temperature rose to only -5 degrees F that the thermostat shut the furnace down by 8 am and it didn

start up until the early evening. The media caught wind of the story. Newsreels and national magazines sprea

the word about the house that needed very little heating fuel even in subzero weather. One newspaperman calle

the house a solar home. The name stuck. By 1941 Keck had designed the first completely solar-oriente

community to be built in modern America. After the war, a nation-wide construction firm, hired Keck as it

architect and advertised solar house as The most talked about home in America. While interest in solar homes

peaked in the early 1950s, those built did not fall apart or stop working. The family occupying one of Kecks sola

houses, for example, reported in 1979, according to the Chicago Sun Times, The temperature can dip to zero

but if the sun is shining, the family turns off their furnace as soon as they get out of bed in the morning

Otherwise the house gets too warm. The Sun Times reporter later visited the house on one of the most stiflingl

hot days of August. Sitting in the living room, she found the interior pleasant although none of the a

conditioners was operating.

Chapter 20: Solar Collectors for House Heating (1882-1962)

The earliest instance of putting to work the solar hot box for house heating dates back to the early 1880s whe

Edward S. Morse, a self-taught world renowned botanist and ethnologist, attached a device closely resembling

large hot box to the south wall of a building with vents that permitted outdoor air to enter the box and natural

flow up as it heated eventually heating the interior rooms. Scientific American called the invention an ingeniou


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arrangement for utilizing the suns rays in warming our houses. It is so simple and self-contained that on

wonders that it has not always been in use.

Godfrey Lowell, a wealthy Bostonian, decided to fund research at M.I.T for finding ways to economically hea

houses with the sun. For the first house, engineers covered the roof with solar water heater collectors similar to

ones built by Day and Night. Instead of using the hot water for bathing or washing the dishes, it went into

17,000 gallon storage tank. Air blown over the tank warmed and circulated hot air into the house when it cooledown..

To develop a more cost-effective system, M.I.T. workers combined the functions of collecting, storing, and

distributing solar heat into a single unit. They stacked water cans behind a south-facing glass faade of a lon

and narrow laboratory consisting of ten cubicles. During the day solar energy heated the water in the cans

Insulating curtains separated the interior of the cubicles from the warming water cans when the interior got to

hot and opened when any of the cubicles needed heat. Insulating shades between the heated cans and the glas

were shut at night to keep their heat from radiating back into the night sky. These simple water walls supplied u

to 48% of a cubicles heating needs throughout the very cold New England winter.

The third M.I.T. House combined solar architectural strategies with solar heat collectors. In its three years o

operation between 1949 and 1952 the south-facing windows supplied between 33 and 39% of the heat to th

house while the collectors provided 36% to 49% of the houses heating needs. Body heat and waste heat from

appliances contributed another 16%. The free heat from the sun and activities inside left a very small amoun

needed from an electric heater.

V. Photovoltaics

Chapter 21: From Selenium to Silicon (1876-)

Willoughby Smith, an English electrical engineer, reported in 1872 the light sensitivity of selenium. Exposure to

sunlight increased the materials conductivity. The discovery intrigued European physicists. In 1876 two British

scientists, William Grylls Adams and Richard Evans Day, discovered that light shone on these bars produced

something never seen before: light, not heat, generating a flow of electricity in a solid material. Adams and Da

called current produced this way, photoelectric. Today, it is known as the photovoltaic effect. American invento

Charles Fritts put together selenium modules and placed a test array on a New York rooftop in the mid 1880s. H

optimistically predicted that soon his modules would compete on the market place with the new electric powe

plants established by Thomas Edison. Many envisioned Fritts invention as entirely superseding the steam engin

and ending all the pollution endemic to them. But try as they may, no one could increase seleniums low

conversion of sunlight into electricity and scientists concluded that to realize the vision of photovoltaics powerin

the world would require finding a new photovoltaic material.

While working on the newly-discovered silicon transistor, Daryl Chapin, Calvin Fuller and Gerald Pearson of Bel


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Laboratories came up with a solar cell that could convert enough solar energy into electricity to run everyday

electrical equipment. The New York Times praised the discovery as the beginning of a new era, leading

eventually to the realization of one of mankinds most cherished dreams - the harnessing of the almost limitles

energy of the sun for the uses of civilization.

Chapter 22: Saved by the Space Race (1958-)

Despite grandiose praise for the new solar cell from the media suggesting the new device would one da

provide more power than all the worlds coal, oil and uranium, for the first years after its discovery application

remained elusive. The military though showed intense interest. Both the Air Force and the Army viewed the Be

invention as vital for its top-secret satellite program. Thanks to its semiconductor twin the transistor the powe

draw of the electronics onboard was so reduced that solar cells would suffice to run them. The successful launch

of Americas Vanguard, the worlds first satellite relying on silicon solar cells for powering the instruments on

board, proved the value of the Bell invention. Their longevity made photovoltaics a critical component for th

growing American and Russian space programs. Prior satellites, including the first two sputniks, powered solel

by batteries died after only several weeks in orbit compared with solar-powered satellites that lasted for yearsTheir new found life span has revolutionized life on Earth. It turned Space into a battlefield giving the Americans

birds-eye view of their adversary and providing pin-point accuracy of its missiles. Telecommunication satellites

made world-wide telephony ubiquitous and cheap. Global news became instantaneous. Dish TV has brough

television to millions. Cellular would be unthinkable. The unexpected and relatively large demand for solar cells

for space proved crucial for the photovoltaics commercialization, development and future successes.

Chapter 23: The First Large-Scale Photovoltaic Applications on Earth (1968 -)

The success of photovoltaics in Space gave those a vision of how solar cells might benefit activities down onEarth, especially for remote terrestrial electrical demand where power lines do not reach. The first commercia

use of photovoltaics on Earth powered navigation horns and lights on offshore oil rigs previously run by hug

batteries. Coast Guards throughout the world adopted photovoltaics to run their buoys and lighthouses

Photovoltaic-powered microwave repeaters connected remote towns and homesteads to the telecommunicatio

grid, allowing them to access the same radio, telephone and television services that their urban neighbors had t

long enjoyed. By the mid 1980s, photovoltaics had become the energy source of choice worldwide for remote

industrial power needs.

VI The Post -Oil Embargo Era

Chapter 24: Prelude to the Embargo (1945-1973)

During the first three decades after World War 11, few people in the United States and most other western

countries made use of solar energy. Oil, gas, and electricity were cheap and getting cheaper. Active promotion

by utilities resulted in a much more fuel-intensive life-style. Electric consumption alone increased fourteen fold

The gas companies also succeeded in selling record amounts. A few far-sighted individuals at the time warned o


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an impending energy crisis. As early as 1952 the Presidents Materials Commission appointed by Harry S

Truman came out with a report predicting that America and its allies would be short of fossil fuels by 1975. The

report urged that solar energy be developed as a replacement.

What the country didnt know was that it had an oil shortage going on for many years before. In 1947 America

domestic production slipped below its consumption and the country had become a net importer of oil. As long as

the supply stayed cheap and kept flowing, no one cared. When the oil embargo hit in October 1973, the Unite

States and much of the rest of the world woke up high energy prices and long gas lines at the pumps. The Unite

States government did have one energy alternative in mind nuclear power. It wasnt really an energy choice

though but a Cold War solution to a very sticky problem. In 1954 the Americans were the only possessors of the

hydrogen bomb and such a weapon had scared the world out of its wits. To counter these fears, the United

States government presented the Good Atom, the Peaceful Atom, by supporting of the development of nuclea

power through its Atoms for Peace program. Although the Presidents Materials Commission had proposed a

equally weighted research effort for solar and nuclear, the American government under the incoming Eisenhowe

Administration and until Obama took office remained biased towards the nuclear option. The discovery o

previously unseen documents reveal the strong support for solar, especially solar photovoltaics, by expe

advisory groups to various presidential administrations from Eisenhower to Reagan, only to be rejected and

suppressed by them to perpetuate support for fossil fuels and nuclear energy.

Chapter 25: Solar Successes in the 1970s and 1980s

In response to the oil crisis of 1973, people took a new look at the potential of solar energy to replace fossil fuels

and nuclear energy. Many embraced solar energy because it seemed to offer an environmental, political an

social alternative to the old corporate structure running oil, coal and nuclear power. These attributes especiall

appealed to those who had formerly opposed the Vietnam War and had been involved in the counterculture o

the 1960s. It is therefore not without irony that swimming pools, associated with wealth and social decadence

became the first success story of solar in America during the 1970s and 1980s. Inexpensive plastic solar-poo

heaters dominated the solar market for almost a decade. The other solar success story came from opposite

spectrum with hippies applying solar ideas to drop out from Korporate America in comfort. Their inspiration came

from indigenous architecture that had made maximal use of the resources surrounding them, especially the sun

with minimal reliance on technology and capital, just had the Chinese, Greeks and Romans had done, too. Ope

minded engineers analyzed these new approaches and concluded that they worked, and in many situations

even better, than ever increasing sophisticated heating and ventilating equipment. Those building with nature

rather than fighting it as had been the case in the construction industry, gained increasing popularity amon

architects, engineers, scientists, bureaucrats and the public. Raymond Bliss, for example, a physicist, writing fo

the prestigious Bulletin of the Atomic Scientists, demonstrated more energy could be saved through the massive

building of well designed solar homes than all the oil drilled on the Alaskan slope compared to oil drilled from

Alaskas North Slope.

Chapter 26: Americas First Solar City (1920s-)


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Davis, California has had a rich solar legacy. Studies of early solar water heaters began in the late 1920s too

place there at the University of Californias Agriculture Experimental Station. By the 1940s the work of George

Fred Keck and MIT helped introduce ideas of solar architecture at the local university. Work on solar orienting

animal enclosures for healthier poultry and livestock commenced at the Davis campus during the 1950s, as di

the study of microclimates for better crop management. Interest also developed in using vegetation for climate

control of farm workers housing. All of these issues became the core curriculum for many. Applying what they

learned at the university to the local setting became imperative for students turned activists during the 1970sWith the support of a newly elected city council sympathetic to such ideas, the Davis Solar Ordinance became

law. Its passage inspired at the far end of the city the development of Village Homes, the largest planned

aggregation of passive sun-oriented living spaces since the construction of Olynthus.

Chapter 27: Solar Water Heating Worldwide Part II (1973-)

The oil shocks of 1973, 1979, and 1980 brought renewed interest in using the sun to heat water and building

and generate power for industry. A million solar water heaters were installed in the United State between 1973

and 1986. Seven million were put up in Japan. Declining oil prices and increasing supplies in the mid 1980eclipsed interest in the solar alternative in these two large markets. Solar water heating did not die though. It jus

spread to other countries in need of a good option to fossil fuels, giving rise to an even more vibrant and

international solar water industry. Government intervention combined with high energy costs in Cyprus and Israe

has resulted in these two Mediterranean countries being highest per capita users of solar water heating in the

world. Today, more than 90% of all Cypriot and Israeli households rely on the sun for hot water. Austria an

Barbados rank third and fourth. In Austria, one out of eight households heats their water with solar and many o

them have combined solar water heating with house heating. The people of Barbados have seen the island

solar water heater industry grow from a few hundred in 1974 to make up 50% of the water heaters now, reducinthe countrys dependence on imported oil. That the largest solar water heating installation resides on Aero Islan

off the west coast of Denmark might surely comes as a surprise to many. China though dominates the

international solar water heating market with nearly 80% of all installations. Currently more than 50,000,000 sola

water heaters worldwide produce an energy equivalent of 124 million barrels of oil on an annual basis.

Chapter 28: Photovoltaics for the World (1978-)

For many years rural electrification experts planned to power the developing worlds towns and villages the same

way that Western countries had by building centralized generating plants and stringing wires to individuahomes. Running transmission lines in this way has proven very costly with little chance of return on the

investment. As a consequence they bypass most of those living outside urban areas, leaving billions withou

access electricity and relying on ad hoc solutions such as generators, kerosene lamps, candles and fire

Kerosene lamps, candles and fire provide poor lighting, emit suffocating smoke and always entail the danger o

burning consumers and their homes. All of these options also require imported fuel not always available bu

always expensive. In contrast, if properly installed and maintained, a solar module will generate electricity fo

decades. Photovoltaics, combined with storage, offers complete energy autonomy. France led the way in sola


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rural electrification by deciding in 1978 to put panels on all huts in the outlying islands of the South Pacific

Middle-class Kenyans living outside of the larger cities purchase their own electrical power stations by buying

modules at the local general store. More rural Kenyans have plugged into the sun than into the national grid. Th

experiences in French Tahiti and Kenya suggest that the principal power source in the non-electrified world wi

be solar.

When Charles Fritts boldly predicted that his selenium solar panels might soon compete with Thomas Edison

coal-fired power plants, he had no intention of constructing large-scale generating stations. Rather, he believed

the selenium modules would enable each building to have its own plant. Shell oil came to the same conclusio

a hundred years later, stating, In our opinion, the dispersed generation of photovoltaic energy affords the earlies

opportunity for photovoltaics to contribute to Americas growing energy needs. Markus Real, a Swiss engineer

put the vision of Fritts and Shell Oil to the test when he installed 3 kilowatt solar power stations on three hundre

rooftops in Zurich. As Real logically put it, It makes sense, absolute sense. The roof is there. The roof is free

The electrical connections are there. The avoidance of transmission, Real brilliantly realized, allows solar to

compete against the retail cost of electricity which far exceeds the wholesale price at the point of generation. Th

Zurich experience led to many nationally supported rooftop programs, culminating in Germany in 1999 with th

national feed-in-tariff which generously rewarded those who chose the sun as their energy source. The Germa

feed-in-tariff, combined with the mass production of photovoltaics in China and its subsequent low price, grew

installations from less than a gigawatt worldwide in 1999 to more than a hundred as of today.

Chapter 29: Better Cells, Cheaper Cells (1956-)

To realize the dream of solar cells covering the world's rooftops and powering utilities, their price must continu

to drop. Presently crystalline silicon remains the dominant photovoltaic material, basically the same substanc

that was discovered at Bell Laboratories in the early 1950s. Its continued widespread use rests on the fact that

as one expert explained, "It works and it works for a long. Automation, economies of scale and better use of th

incoming light has brought the price down of silicon solar cells from almost $300 per watt to under a dollar

Another avenue for bringing down the cost involves depositing a small amount of a photovoltaically activ

substance onto an inexpensive supporting material, such as glass or plastic. Solar cells made in this fashion

are called thin films. It has long been believed that this process would consume much less of the expensive

photovoltaic ingredients and that it would also lend itself to automation. Despite many attempts, thin films hav

not reached efficiencies comparable to silicon, leaving silicon solar cells to continue their reign as the work hors

of the industry. In the 1980s, people argued whether the price of phototovoltaics would get down bein

competitive with electricity from transmission lines, which those in the industry call grid parity. Coming to the

end of the first decade of the 21st century, everyone agrees grid parity has already been reached at some sunny

regions of the world where the price of electricity is extremely high and will soon extend to the rest of the globe i

the next few years, depending on the amount of solar radiation received and the cost of electricity arriving at th

point of demand.


12/12

Epilogue

When I tell people that I have published a book on a history of solar energy book, everyone comments, It mus

be very thin. To their surprise, Let It Shine: The 6000-Year Story of Solar Energy, has 451 pages! Grea

progress has been made in the solar field. When the first silicon-solar array was built in 1954, it consisted of les

than a watt. Since then, one hundred billion watts have been installed. Over the last decade the heating capacit

of the solar water heater industry has grown six fold. Solar concentrators have grown from a few kilowatts in

1980 to several million today. No one reading the mainstream media could know that solar has made such

progress. It is my hope that my new book will bring new light to the progress of solar energy. The disasters o

Fukushima and Hurricane Sandy have given to momentum to solar. By combining the oldest and the newes

solar technologies architecture and photovoltaics the autonomous house becomes possible. Its developmen

could do away with power lines altogether, just as cell phones have gone wireless and in the process diminishe

the importance of land lines. The increasing use of solar energy will reduce our dependence on nuclear and foss

fuels, reducing the danger of radioactive fallout and global warming and their consequences that threaten th

well-being of all things both big and small including us. As energy expert Amory Lovins pointed ou

Rediscovering our solar rootstocks, and grafting modern efficiency technologies to them, offers good new

indeed for all people, and for the earth.

Documents

The 6000 Year Story of Solar Energy