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“Since the development of the first semiconductor-based forms of the solar panel, the steady
improvement in designs and efficiency has progressively led to its domination of global energy harvesting. Solar power is
now a major contributor to national power grids straining to address energy demand. Microgrid implementations secure power
for communities too remote for connection to urban networks, while solar lamps can provide night-time power in even less
well-endowed communities. Interconversion between electrical energy and light continues to blaze new paths of application,
empowering human lives and transforming societies.” (Ref. 1)
On 26 April 1954, a headline appeared on the front page of the New York Times: "Vast Power
of the Sun Is Trapped by Battery Using Sand Ingredient." This headline foreshadowed the 2008 induction of Gerald L. Pearson
into the National Inventors Hall of Fame for his co-invention of the silicon solar cell.
Efforts to capture solar energy for human use began decades before Pearson was born. In 1839,
French physicist Edmond Becquerel measured a small voltage between platinum electrodes in an acidic solution containing silver
chloride illuminated by sunlight. British engineer Willoughby Smith later discovered photoconductivity in selenium in 1873,
and in 1883 American inventor Charles Edgar Fritts applied gold leaf to selenium to make the first solar cell. However, its
anemic efficiency, less than one percent, made it impractical.
An important experiment in silicon physics at Bell Labs in 1940 marked a big step in solar cells.
Russell Ohl found that illuminating a cracked sample of silicon with different impurity levels on the two sides of the crack
produced a surprisingly strong voltage across the crack. It led to Ohl's observation of the first junction of silicon regions
doped with positive and negative impurities - a key to the first silicon solar cell.
After World War II, Bell Labs returned to work on semiconductors in 1946. A practical problem roused
Bell Lab's interest in solar power. The dry cell batteries used to power remote telephone equipment degraded quickly in humid
regions, and in 1952 Bell asked an engineer to study other possible power sources. The engineer thought solar cells might work,
but wanted more efficiency than selenium could offer, so he asked Gerald Pearson, a personal friend, about
alternatives.
Pearson told the engineer to drop selenium and switch to silicon. Modifying the chemical properties
of the silicon cells, the Bell engineers were able to convert 6% of the solar energy falling on the silicon cell into
electricity, beating the 1% that MIT had reported in 1947. 6% was the target for the telephone application, though it was
calculated that an ideal silicon solar cell could convert 23% of sunlight into electricity.
The Bell engineers submitted a letter to the Journal of Applied Physics. Bell Lab's solar
cell made the front page of the Times on 26 April 1954, appearing between announcement of the first large-scale test
of the Salk polio vaccine and a gangland killing in New York. The Times projected solar cells might someday harness
the "almost limitless energy of the sun for the uses of civilization."
Solar cells captured the public's imagination. Edmund Scientific sold them in their catalog in the
1960s for $2.25. Crucially, solar cells powered the space race, since all satellites built to last more than a month required
solar power.[2]
The National Renewable Energy Laboratory (NREL) is a federal laboratory dedicated to clean energy
research and development. It helps identify, develop, engineer, and design manufacturing processes for new photovoltaic (PV)
products, e.g., photovoltaic solar cells. It also helps advance the deployment of solar infrastructure in the US through
work designed to lower costs, improve solar integration onto the grid, and provide technical assistance for state and
regulatory authorities.
Solar accounted for 43% of all new electricity generating capacity in 2020 - first among all
technologies for the second year in a row. There are four primary drivers of the acceleration of solar adoption.
First, the rapid drop in price has made solar competitive with traditional sources of power generation in large parts of the US.
NREL estimates that from 2010 to 2020, the cost of energy for US utility-scale PV systems dropped 83 percent. Second, the
federal government extended the investment tax credit (ITC), first in 2015, and then again in 2020. Third, many states have
set aggressive targets, requiring electricity supplied within their state to come from renewable energy sources, and/or set
up regulations encouraging commercial and residential PV deployment. Many utilities now have mandates to procure a certain
amount of electricity from renewable sources, which goes up over time. What's more, most commercial and residential customers
in the US now have the ability to feed electricity into the grid from their solar-energy systems and get retail credit for
the energy. Finally, as part of their environmental sustainability plans, many corporations now procure a large amount of
their energy needs from solar energy.
Solar panels continue to get cheaper and more efficient, requiring less labor and supporting
material for the same amount of energy at a cheaper price. Geography plays an important role in residential PV
installation. PV panels do produce more electricity in places like Arizona. Still, PV can be competitive in regions with less
sun depending on other factors, such as the cost of retail electricity in that area. Washington state gets a significant
portion of its energy from very inexpensive hydropower, for example, whereas New York City has an old, expensive distribution
grid.[3]
The solar energy industry is growing exponentially in the U.S. In 2020, the U.S. solar market increased
by 43%
over 2019, making 2020 a record-setting year. Better still, the costs of solar photovoltaic systems continued to drop, making
solar energy resources more affordable for everyone in the U.S. The Solar Energy Industries Association (SEIA) said that
business was booming and not about to stop anytime soon. Prices fell by more than 70% in the past decade leading to
unprecedented growth in the industry. The total share of electricity generated in the U.S. was only 0.1% in 2010 but
had grown to more than 3% by 2020. The SEIA reports that solar installations will likely double by 2023 and quadruple by 2030
from current levels.
There are now 35 utility-scale solar energy plants in the USA, whereas 10 years ago there wasn’t even
one. According to the SEIA report, California is still the solar leader, followed by Texas. With the highest electricity rates
in the U.S. and strong state incentives, it’s not difficult to understand California consumer buy-in to solar energy.
California is also the first U.S. state to mandate that all new single-family and multi-family homes up to three stories
high must incorporate solar panels.
In addition to California, Texas, and Florida, many other states are ranking up their support for
solar. Even though it is still primarily those in hotter states that are increasing volumes, there is increasing evidence of
the effectiveness of solar in cold climates. In 2018, the top U.S. states for solar installations were: California, North
Carolina, Arizona, Nevada, Texas, New Jersey, Massachusetts, Florida, and New York.
There has been an enormous growth of solar in the USA in the past decade. Admittedly, the percentage
rates of the share of electricity generated are still very low, with only about 4% of homes in the country boasting solar
installations. But this is changing rapidly. In the last quarter of 2020 alone, solar increased by 32%.
There is also strong evidence that an increasing number of states are adding solar capacity.
When (rather than if) more states follow the lead of California, Texas, and Florida, the speed of growth will be even greater.
The growth of the solar industry is picking up steam and there appears to be no turning back from here, given the lower cost
and mass adoption rate.[4]
Consumers burn fossil fuels because it's cost-efficient and convenient - for now. However, fossil
fuels do not produce renewable energy because their global supply is finite. Solar energy, however, is a truly renewable
source of natural energy. However, the amount of solar energy - sunlight - we receive varies depending on location, time of
day, season and weather conditions.
As with all power sources, solar energy has its pros and cons. The two main disadvantages of solar
energy are its high upfront costs for consumers and low energy density. For fossil fuels, the health, environmental and
economic costs are considered to outweigh their value.
Going solar is a money-saver in the long term, even though startup costs are higher for the consumer.
Currently, electricity from fossil fuels costs between 5 cents and 17 cents per kilowatt-hour. On the other hand, solar energy
costs average between 3 cents and 6 cents per kilowatt-hour and are trending down, according to the NREL.
In 2020, the initial installation and setup of a solar energy system in the U.S. costs an average of
about $15,000 after state incentives. The cost for solar panels has decreased more than 20% in the last five years and is
expected to continue declining.
Once installed, a solar energy system is low-maintenance and low-cost. Homeowners might even be able
to make money by selling excess energy produced by their solar panels back to their local grid. Full solar panel systems can
require a substantial upfront investment. Some homeowners mitigate the initial expense with the money saved on their utility
bills, but not everyone is in the financial position to absorb the cost until it balances out. To help offset the initial
cost of installing solar panels, many solar energy companies have leasing and solar financing options available.
The earth absorbs enough energy from the sun in about an hour to power the world for a year. To use
solar energy for the electricity we use in our homes, we must convert the solar power into electrical power with solar
panels.
Solar panels are made of photovoltaic (PV) cells that convert solar energy into electrical energy. In a
solar panel system, energy from the sun is collected, converted to electricity and then stored in batteries. Batteries are
used with the solar cells to provide electrical power after sunset, during cloudy weather, or offset electricity
usage.
There are some environmental disadvantages of solar energy because of pollution associated with
solar cell production. Also, transporting solar panel systems contributes to greenhouse gas emissions. Still, the
environmental problems with solar energy production have significantly less impact than those caused by fossil fuels.
The most significant advantage of fossil fuels has been that our technology for turning them into
energy is well developed. Historically, nonrenewable fossil fuel has been easy to find and reliably used across the
globe. We've had centuries to perfect how we use it. But - and it’s a big but today - fossil fuels are a top contributor to
global warming because of their high carbon output when burned. There's also the potential for dangerous accidents during
the production and transportation of fossil fuels.
Given the consumption rate of fossil fuels, the world is reaching a point where there will be little
choice in the matter. Nonrenewable fossil fuels are extracted at a much faster rate than they're being replenished. Because
of this, some fossil fuels, like coal, are on track to be more expensive than solar within the next decade.
When considering the environmental impact of solar power versus fossil fuels, solar power is clearly
the more environmentally friendly option. Still, many consumers prefer fossil fuels for their perceived
reliability.[5]
A view of the future may be seen from recent legislation put into effect in California which mirrors
actions taken in Israel decades ago. During the 1950's there was a fuel supply shortage in Israel and restrictions were placed
on when people could heat their water. Many Israelis started to purchase solar water heaters. In 1980, the Israeli Knesset
passed a law making solar water heating mandatory for new
residential buildings. The law has saved Israel and its citizens millions of dollars in energy costs since then. Purchasing
and installing (usually by the builders) a solar water heating system has been common practice in Israel ever since.
The solar energy for the roof-top water heaters in Israel was - and still is - used to produce heat,
not electrical energy. This action saved the electrical power - and the fuel to generate it - that would have been needed
to heat the water. Israel is still one of the top countries in the world (percentage of population) using solar heaters and
saving money on water heating bills.
On the stroke of midnight on New Year’s Eve 2020, California, the nation’s most populous
state, required that every newly-built home had to come with enough solar panels to satisfy its electricity
needs.
At the time, solar panels were installed on just 20% of new homes in the state. That figure would
rise to 100% for every home under four stories tall (with a few exceptions). The California Energy Commission (CEC) expected
this to add 74,000 new solar installations in 2020.
The cost of the solar systems - about $8,400 per unit on average - would be offset by long-term
savings. Builders were rolling the installation costs into 25-year leases so buyers did not pay upfront. The CEC estimated
solar systems added $40 per more in monthly mortgage payment but saved about $80 on electricity bills each month.
Other states were starting to follow California’s lead. Massachusetts, which aimed to cut carbon
emissions 80% below 1990 levels by 2050, was considering a mandate for solar panels on most new construction, effectively
doubling the state’s solar capacity. California’s new building codes were cited as inspiration. Eight states (and the District
of Columbia and Puerto Rico) were targeting 100% renewable or carbon-free electricity by
2050.[6]
What follows is a summary of a report on solar energy in the decade of 2020 to 2030 from the
World Economic Forum Annual Meeting that was held in Davos-Klosters Switzerland in January of 2020.
Solar energy has come a long way in a decade. Back in 2010, the global market was small and highly
dependent on subsidy regimes in countries such as Germany and Italy. "This year {2020} there will be more than 115
gigawatts (GW) of solar installed across the world, which is more than all other generation technologies put together."
It is also increasingly low cost, especially in sunnier regions where it has already become the lowest-cost form of new
electricity generation.
In the coming years, technology improvements will ensure that solar becomes even cheaper. It could
well be that by 2030, solar will have become the most important source of energy for electricity production in a large part
of the world. This will also have a positive impact on the environment and climate change.
Going forward, the solar industry has very clear cost-reduction roadmaps, which should see
solar costs halving by 2030. There is already a move in place towards higher-efficiency modules, which can
generate 1.5 times more power than existing, similarly sized modules today using a technology called tandem silicon cells.
These are going to have a large impact in the coming years.
In addition, there are production innovations coming down the pipeline that will reduce the amounts
of costly materials such as silver used in the manufacture of solar cells, as well as innovations such as bifacial modules
which allow panels to capture solar energy simultaneously from both front and back. The other important innovation is around
how best to integrate solar into our homes, businesses and power systems. This means better power electronics and a greater
use of low-cost digital technologies.
In many parts of the world, what this means is that the cost of solar electrical energy will be so
low as to make it unbeatable compared to fossil fuels. Given that solar is so easy and quick to install, not to mention
flexible - after all, solar can be used to power something as small as a watch or as large as a city - it should mean that
solar installations will continue to grow over years 2020 to 2030. This should also be very beneficial for the
environment.[7]
Solar electrical energy generation has progressed enormously since the first solid-state
photovoltaic cells were fabricated about 75-years ago. They were originally single cell devices that could generate a
weak signal when stimulated by light. Today we have multi-cell arrays that generate enough power to light up our houses.
Solar electrical energy generation is cost competitive with other forms of energy generation. Solar electrical energy
generation is non-polluting and the energy generated is renewable - as long as the sun continues to shine.
Performance is constantly being improved and fabrication costs are being reduced. The future appears bright for solar
electrical energy.
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References:
- 2021 / The Power of Light, David Andrews, PHOTONICS FOCUS, Page 38, July/August 2021.
- Gerald Pearson: trapping the vast power of the sun, Jeff Hecht, SPIE, 1 July 2021.
- A conversation about solar, William G. Schulz, SPIE, 1 July 2021.
- How Fast is The Solar Energy Industry Growing in the USA?, Erin Shine, attainablehome.com,
27 April 2021.
- Solar Energy vs. Fossil Fuels, Kathryn Parkman, ConsumerAffairs, 27 April 2021.
- How California is making solar power the standard, Michael J. Coren, World Economic Forum,
16 January 2020.
- The future looks bright for solar energy, Gerard Reid, World Economic Forum,
16 January 2020.
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