Solar Electrical Energy

Solar Electrical Energy

© David Burton 2021

Solar Electrical Emergy

     “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.

  1. 2021 / The Power of Light, David Andrews, PHOTONICS FOCUS, Page 38, July/August 2021.
  2. Gerald Pearson: trapping the vast power of the sun, Jeff Hecht, SPIE, 1 July 2021.
  3. A conversation about solar, William G. Schulz, SPIE, 1 July 2021.
  4. How Fast is The Solar Energy Industry Growing in the USA?, Erin Shine,, 27 April 2021.
  5. Solar Energy vs. Fossil Fuels, Kathryn Parkman, ConsumerAffairs, 27 April 2021.
  6. How California is making solar power the standard, Michael J. Coren, World Economic Forum,
    16 January 2020.
  7. The future looks bright for solar energy, Gerard Reid, World Economic Forum, 16 January 2020.

  9 September 2021 {Article 492; Suggestions?_61}    
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