Solar Power


Located 150 million km from the sun, Earth receives just one-billionth of the sun’s colossal power output. But even that tiny fraction, some 120,000 trillion watts, showers Earth with more energy in one hour than all the energy consumed by humans in an entire year. link
Solar power is probably, along with wind power, the most  readily available solution to clean energy alternatives. Technology is advancing rapidly to make solar energy both efficient and low-cost
. This page provides illustrations  of technological developments around the world and examples where solar is being used, looking at both Photovoltaic (PV) and Concentrated Solar Power (CSP) alternatives. March 2016:  Germany leads top 10 countries using solar power - link         

NEW:  How much land would it take to power the world’s major cities by solar? This interactive site takes a look to see how little land is needed to power world cities by solar. link  

Latest news:

Oct. 12 2017: Can U.S. solar advocates become as powerful as the NRA? There has been talk for years about the need for the industry to mobilize rooftop solar owners into one group that together would represent one large voice in favor of solar-friendly local, state and federal policy. With more than one million installations in the U.S. that voice would certainly be loud and strong.  link   Solar United Neighbors is the only organization in the country dedicated to representing the needs and interests of solar owners and supporters. Helping people go solar, join together, and fight for their energy rights since 2007



  • News from around the world
  • The place of solar in the USA today
  • Explaining difference between PV and CSP and Suncatcher
  • Costs of solar energy
  • Desertec and desalination
  • Other technical news
  • Floating solar 
  • Feed-in tariffs and municipal lending
Every day the sun provides approximately 170,000 terawatt hours of energy -
about 2,850 times the energy required by people around the world.
  • In 40 minutes of daylight the sun releases upon the earth the amount of energy that is consumed by the entire population of the planet in one year.
  • All the energy stored in Earth's reserves of coal, oil, and natural gas is matched by the energy from just 20 days of sunshine.  
  • Currently we harness about 1% of this energy.
Since 2010, the world has added more solar photovoltaic (PV) capacity than in the previous four decades. Total global capacity overtook 150GW in early 2014   link  

News from around the world 

March 2017: Solar power added worldwide in 2016 to reach 305GW. New solar photovoltaic capacity installed in 2016 reached more than 76GW, a dramatic increase on the 50GW installed in 2015. China and the US led the surge, with both countries almost doubling the amount of solar they added in 2015. Globally there is now 305GW of solar power capacity, up from around 50GW in 2010 and virtually nothing at the turn of the millennium. link

March 2016: Ten countires that lead the world in solar energy. What's surprising about the top 10 list is that relatively tiny countries are on it. Germany, Japan and Italy all rank higher than the much larger US, which is ranked 5th. (China raked 2nd.)  link

January 2017: Global solar installations could reach 70GW energy in 2017.  link

December 2016: Solar power now cheaper than wind. Now, unsubsidized solar is beginning to outcompete coal and natural gas on a larger scale, and notably, new solar projects in emerging markets are costing less to build than wind projects, according to fresh data from Bloomberg New Energy Finance. The overall shift to clean energy can be more expensive in wealthier nations, where electricity demand is flat or falling and new solar must compete with existing billion-dollar coal and gas plants. But in countries that are adding new electricity capacity as quickly as possible, renewable energy canl beat any other technology in most of the world without subsidies  link

April 2016: International solar alliance to mobilize $1 trillion. During the historic signing of the Paris Climate Agreement at the UN, the first meeting of the International Solar Alliance also took place. When launched at the Paris summit, 120 countries signed onto the alliance declaring: “United by our objective to significantly augment solar power generation in our countries, we intend making joint efforts through innovative policies, projects, programmes, capacity building measures and financial instruments to mobilize more than 1000 Billion US Dollars of investments that are needed by 2030 for the massive deployment of affordable solar energy."  link    

June 2015: Around 40GW of solar power was installed in 2014. A record amount of solar power was added to the world’s grids in 2014, pushing total cumulative capacity to 100 times the level it was in 2000.  link

June 2014: China becomes world's largest PV market. According to the Global New Energy Development Report 2014, China has surpassed Germany as the world's largest PV market. The report provided a comprehensive and authoritative overview of the global renewable energy market. The global PV market saw 38.7GW  of new capacity installed in 2013, bringing the cumulative installed PV capacity to over 140GW, the report said. New PV installations in China saw the addition of 12GW in 2013, up 232% year on year, demonstrating that the global PV market has gradually shifted from Europe to Asia. link

January 2014: Middle-East looks at $50 billion to spend on solar power by 2020. The Middle East, spearheaded by the oil-rich Persian Gulf monarchies, could spend up to $50 billion on developing solar power over the next seven years, says the Middle East Solar Industry Association. The MESIA group estimates the region will install 12,000-15,000MW of solar power by 2020, with another 22,000-25,000GW from other renewable energy sources such as wind and hydro-power. link

August 2013: Germany leads world - US 20th. In terms of total solar power capacity per capita, Germany crushes every other country. At the end of 2012, it had approximately 400MW of solar power capacity per million people, considerably more than #2 Italy at 267MW per million people, #3 Belgium at 254MW per million people,  #4 Czech Republic at 204MW per million, and #5 Greece at 143MW per million people. The US came it at #20 with about 25 MW per million people. link

June 2012: Japan poised to become second biggest market. Japan is poised to overtake Italy and become the world’s second-biggest market for solar power as incentives starting July 1 propel sales. It could eventually top Germany, which holds the No. 1 spot. link

March 2010:
power could make up as much as 25% of the world’s total electricity production by 2050. link

                 How solar is expanding around the world - - nine examples      

April 2017: Global installed PV capacity reaches 303 Gigawatts.  The IEA reported that 75GW of solar were installed globally in 2016 bringing the installed global photovoltaic capacity to at least 303 gigawatts. This was an increase of 51GW in 2015 and 40GW in 2014. The 2015 total of 227GW of PV cumulatively installed around the world meant solar power made up more than 1.2% of global electricity demand. link

India: As of July 2016, India’s total grid-connected solar power capacity reached the 8GW mark. India’s ambitious target is for 100 GW installed capacity by 2022. link

Morocco: (February 2016) Morocco begins phase one of world’s largest solar plant. The power station on the edge of the Saharan desert will be the size of the country’s capital city by the time it is finished in 2018, and provide electricity for 1.1 million people. Noor 1, the first section at the town of Ouarzazate, provides 160MW of the ultimate 580MW capacity.  link   

Italy: (February 2016) Solar PV provides 7.8% of Italy’s electricity. Solar PV systems in Italy in 2015 generated 24,676 GWh of electricity, covering 7.8% of the country’s electricity mix. link

Spain: With around 2,670 MW of annual installations in the year 2008 alone, Spanish Solar PV market will gradually grow and reach total capacity of 33.7GW by 2020. (More on Spain page - link)  (January 2012) World's largest solar plant fires up in Spain.  link

South Africa: The 96MW Jasper solar farm, the continent’s biggest, located near Kimberley in South Africa, is now fully operational. link  At the end of 2016, South Africa had 1529MW of solar capacity, 200MW of which were CSP. link

China: By the end of 2016, total PV capacity in China had increased to over 77.4 GW. More on China's solar ambitions on China page.

Saudi Arabia: January 2013: Saudi Arabia is targeting 54GW of renewable energy by 2032 with solar intended to make up around 42GW of the total. link

Philippines: (March 2016) The 63.3MW Calatagan solar farm in the Philippines, the biggest solar farm in Luzon, claims to be able to power the noontime energy needs of western Batangas. The Calatagan Solar Farm is one of the first of dozens of solar projects completed this year. Experts have said that the Philippines, because of its abundant sunlight, can become one of the world’s first 100% renewable energy-powered economies. link

UAE:  (March 2013) UEA opens world’s largest CSP solar power plant. The 100MW Shams 1 is the world's largest concentrated solar power plant in operation said Sultan al-Jaber,  head of Abu Dhabi’s Masdar, which oversees the emirate's plan to generate 7% of its energy needs from renewable sources by 2020. Masdar now produces 10% of the world's CSP energy.  link  (BBC video)

The place of solar in the USA today

June 2017: Solar now third largest renewable source of electricity in US. In April, solar reached a new milestone, providing more than 2.3% of U.S. electrical supply, meaning solar has now moved into third place among renewable sources, behind hydropower and wind but ahead of biomass and geothermal. link

January 2017: 2016 US solar capacity by state. The U.S. added over 25,000MW of new generation capacity in 2016, according to the U.S. Energy Information, 30% of which was from solar (28% from wind). Despite significant growth in solar installations in the last 10 years, solar still only represents less than 2% of electricity in the U.S. California was clearly ahead of second place North Carolina. link

The top 10 states in the USA in 2015

California leads with 13,241MW of solar capacity capable of powering an estimated 3.32 million homes. Second is Arizona with 2,303 MW then North Carolina with 2,087MW.
Full 10 list - link
How 50 US states compare with solar incentives - source

October 2016: Rooftop solar in US could stall in 2017
: Residential panel installations in the U.S. grew 71% in 2015. In December, Congress unexpectedly extended a tax credit set to expire at the end of 2016. Panel buyers will get reimbursed for 30% of the cost of new solar panels through 2019 and at least 22% through 2021. As solar companies no longer rush to meet a deadline, panel installations are projected to grow by only 0.3% in 2017.
Growth is expected to resume by 2018. (Only 1%  of U.S. households have panels on their roofs.) link

October 2016: World’s largest solar farm planned for Nevada desert. The $5 billion project would rival the capacity of two nuclear power plants for the 2GW Sandstone project. The plan is to use solar-thermal technology, which is more expensive than standard solar PV power, but also has storage capabilities so it can send power to the grid all night long. The sprawling Nevada project would have 10 towers and cover 15,000 acres. The current biggest solar-thermal plant in the world is the 392MW Ivanpah facility in the Mojave Desert in California which doesn’t have storage capability. link

July 2016: Rooftop solar losing out to large-scale solar. Solar power is on pace for the first time this year to contribute more new electricity to the grid than will any other form of energy, a feat driven more by economics than green mandates. The cost of electricity from large-scale solar installations now is comparable to and sometimes cheaper than natural gas-fired power, even without incentives. Unsubsidized utility-scale solar power costs $50 to $70 per megawatt-hour (or 5 to 7 cents a kilowatt hour), compared with $52 to $78 for the most efficient type of gas plant, according to a 2015 study by investment bank Lazard. link

April 2016: Rooftop solar blocked in 10 high-potential states. States with some of the highest solar potential in the U.S. are hindering rooftop-solar development through poor policies, according to a recent report from the Center for Biological Diversity. The report said that 10 states (Alabama, Florida, Georgia, Indiana, Michigan, Oklahoma, Tennessee, Texas, Virginia and Wisconsin) account for more than 35% of the total rooftop-solar potential in the U.S., but have less than 3% of total installed capacity. link

SunShot Initiative - The U.S. Department of Energy's (DOE) SunShot Initiative will reduce the total costs of solar energy systems by about 75% before 2020. This major national effort to make solar energy technologies cost competitive with other forms of energy, without subsidies, will leverage the combined technical expertise of research laboratories, academic institutions, and industry across the country. link 
May 2016:
Update on SunShot initiative. The U.S. now has over 10 times more solar installed today compared to 2011 when the SunShot Initiative was first launched, and the overall costs of solar have dropped by 65%. The cost of installing solar energy in the United States is down more than 50% since the start of a federal support program. The Energy Department said it was about 70% on its way to reaching its goals. Solar power accounts for about 1% of the total electricity consumed in the United States, but represented 30% of the new power generation brought online last year.

December 2015:
Solar crosses threshold of one million homes in US. The US has 27GW of solar installed compared to just 2GW in 2010, and best of all it has reached grid parity in 20 states. link (May 2016) America now produces 27.2 gigawatts of solar energy: What does that mean? link

Home solar in USA – evaluate if it works for you  - check here

March 2016: Blowout year for solar in USA. In 2016 the booming solar sector will add more new electricity-generating capacity than any other, including natural gas and wind. US Energy Information Administration reports that planned installations for 2016 include 9.5GW of utility-scale solar, followed by 8GW natural gas and 6.8GW of wind. This suggests solar could truly blow out the competition, because the EIA numbers are only for large or utility-scale solar arrays or farms and do not include fast-growing rooftop solar, which will also surely add several additional gigawatts of capacity in 2016. link
January 2016: Solar job boom in U.S

September 2013: Utilities divided on rooftop solar in US. Today’s solar industry is puny – it supplies less than 1% of the electricity in the U.S. – but its advocates say that solar is, at long last, ready to move from the fringe of the energy economy to the mainstream. Photovoltaic panel prices are falling. Low-cost financing for installing rooftop solar is available. Federal and state government incentives remain generous. Yet opposition from regulated utilities, which burn fossil fuels to produce most of their electricity, could stop a solar boom before it gets started. Several utilities have asked their state regulators to reduce incentives or impose charges on customers who install rooftop solar; so far, at least, they aren’t making much headway.  But other utility companies are adopting a different strategy – they are joining forces with solar interests. “The industry is divided on how to deal with the opportunity – or threat,” says Nat Kraemer, Clean Power Finance’s founder and CEO. “Some utilities are saying, how I make money off distributed solar, as opposed to how do I fight distributed solar.”  link 

July 2015: US solar production underestimated by 50%. Actual solar electricity production in the United States is 50% higher than previous estimates, according to a new analysis. All told, analysts found that solar energy systems in the U.S. generated 30.4 million megawatt-hours (MWh) of electricity in the 12 months ending in March 2015. Three states - California, Arizona, and Hawaii - can now say that solar provides more than 5% of their total annual electricity demand. The new estimate includes generation from behind-the-meter solar systems, which is not included in estimates produced by the Energy Information Administration.  link  

March 2015: U.S. installs 6.2GW solar PV in 2014 link
March 2014: Spectacular growth in solar supply in 2013.  link
December 2013: US passes Germany on solar installations. link
July 2013: USA becomes 4th nation to install 10GW solar link

May 2013: America’s military is making an unprecedented commitment to renewable energy sources, and solar is “walking point” on many of these new, innovative efforts. As the New York Times reported, “After a decade of waging wars in remote corners of the globe where fuel is not readily available, senior commanders have come to see overdependence on fossil fuel as a big liability, and renewable technologies, which have become more reliable and less expensive over the past few years,as providing a potential answer.” The goal is to have 50% of the power used by the Navy and Marines come from renewable energy sources by 2020 - a seismic shift in Pentagon thinking about energy. link
A federal mandate requires the Army to reduce its energy consumption by 30% by 2015 and generate 25% of its energy from renewable sources by 2025

PV - CSP and SunCatcher

Photovoltaics are those solar panels placed on roofs etc. that so far dominate the solar market. They can be added on buildings anywhere to convert sunshine to electricity direct to the structure. Generally energy output is described in kilowatts produced, and their efficiency of converting the sun's energy to grid-ready electricity is between 8 and 15%. CSP however has an efficiency level of between 15 and 19% and becomes cost-effective when producing in large plants on megawatt scale. The SunCatcher is the most efficient at about 31%.  

CSP  -  Concentrating solar thermal power 

June 2017: CSP costs falling. For a long time, using mirrors to concentrate the sun’s rays to heat molten salt and produce superheated steam to drive a generator’s turbines was thought to be a more promising technology than photovoltaic panels (PV), because it was originally cheaper. But as the price of the panels has dropped dramatically in the last five years, CSP fell out of favour, although some countries continued to support its development. Now the cost of CSP is also falling. But it has another major advantage: unlike the panels, it can go on producing power long after the sun has set, and can store it for up to 15 hours, for use when it’s needed. link

There are three major types of CSP systems:
Power Tower Systems use a large field of Sun-tracking mirrors known asheliostats to focus sunlight onto a central receiver at the top of a tower. The receiver contains a heat-transfer fluid which is heated by the concentrated sunlight. The heat-transfer fluid is used to create steam which drives a conventional turbine generator to produce electricity. CSP has one major advantage over PV: dispatchability. Current CSP plants can store thermal energy for up to 16 hours. 
Dish/Engine Systems use a parabolic dish to focus sunlight onto a receiver located at the focal point of the dish. The dish tracks the Sun in order to take full advantage of the available solar energy. The receiver contains a fluid or gas which is heated by he concentrated sunlight. The heated fluid is used to drive a Stirling engine to produce electricity.  
Parabolic Trough Systems use parabola-shaped reflectors to focus sunlight onto a tube that runs along the focal-line of the reflectors. A heat-transfer fluid inside the tube is heated and used to generate steam to drive a conventional turbine generator which then produces electricity. link

June 2015: CSP bright future.  Solar photovoltaic (PV) systems have seen explosive growth because of their stunning 99% price drop in the past quarter century. As a result, the other form of solar power, concentrating solar thermal power (CSP), is a small fraction of the solar market. But the International Energy Agency (IEA) says CSP has a very bright future too because it enables cheap, efficient storage, which allows CSP plants to provide electricity long after the sun has set. The  IEA suggests 11% of global electricity will be generated by concentrating solar thermal power in 2050. The key attribute of CSP is that it generates primary energy in the form of heat, which can be stored 20 to 100 times more cheaply than electricity, and with far greater efficiency. Commercial projects have already demonstrated that CSP systems can store energy by heating oil or molten salt, which can retain the heat for hours. link

June 2009: Solar-thermal power stations have several advantages over solar-photovoltaic projects. They are typically built on a much larger scale, and historically their costs have been much lower. According to New Energy Finance, about 12GW of concentrating solar-thermal power capacity is being planned worldwide - a vast amount, given that only about 500MW of such capacity has been built to date. link

July 2016: China huge backer of solar CSP providing 24 hour energy. China as a whole has plans to build some 10,000MW of CSP in the next five years. CSP has one huge potential advantage compared to PV - the heat it generates can be stored over 20 times more cheaply than electricity and with far greater efficiency. So CSP’s “killer app” is that it can provide power long after the sun has set and it doesn’t disrupt the grid when a cloud passes overhead. The USA could have been a major force for CSP, but for the collapsing price of PV and misleading statistics about bird casualties. link

Costs of solar energy

September 2017: Cost of U.S. solar drops 75% in 6 years, ahead of federal goal. The goal was set by the Obama administration in 2011 and known as the SunShot Initiative. Now cost-competitive with fossil fuels, the DOE  set a new goal to reduce the cost of solar even further: 3 cents per kilowatt-hour by 2030.  link

December 2013: CPV outlook - demand doubling - costs falling. The PV market in 2007 and early 2008 was shaped by heavy technology development, and a lot of uncertainty as companies struggled to become "bankable" and get financing. link

January 2015: Solar energy competitive and on the rise. As the cost of solar energy production continues to fall, the market is experiencing something of a boom. In many parts of the world, it has become cheaper to produce solar power than diesel oil, gas, coal or nuclear energy. Preliminary statistics suggest that solar energy generation rose by 45GW in 2014, and achieved an output akin to that of 11 large coal or nuclear power stations. But experts say the big boom is yet to come, and are predicting an increase of 50GW for 2015, and a continued upward trajectory in the ensuing years. By 2020, 4% of the world's energy demand could be met with solar power. link

March 2013: Unsubsidized solar reaches grid parity. Deutsche Bank released new analyses concluding that global solar market will become sustainable on its own terms by the end of 2014, no longer needing subsidies to continue performing. The German-based bank said that rooftop solar is looking especially robust, and sees strong demand in solar markets in India, China, Britain, Germany, India, and the United States. As a result, Deutsche Bank actually increased its forecast for solar demand in 2013 to 30 gigawatts — a 20% increase over 2012. link  

July 2010: Crossover point reached - solar now more cost effective than nuclear -  NC Warn report (pdf)

July 2011: Roof panels additional energy benefits. Researchers find solar PV panels have the extra benefit of cooling buildings as well as providing a source of alternative energy. The research team also found that the solar panels had insulating benefits - enabling the building to retain heat during the nighttime. The team found that the cooling effect of the solar panels impacted the building's total energy costs and amounted to a 38% reduction in annual cooling load - the rate at which heat is removed from a conditioned space and the amount required to maintain a constant temperature. link

September 2009: Solar in desert regions face conflicts where water is a major factor. Lack of water availability means less efficiency and higher costs. In California alone, plans are under way for 35 large-scale solar projects that, in bright sunshine, would generate 12,000
megawatts of electricity, equal to the output of about 10 nuclear power plants
. link 

Desertec and desalination

Desertec - the Sahara project that could supply all of Europe's energy.
January 2015: Desertec's plan for Saharan sun to power Europe burns out. As a concept, Desertec was ambitious. Produce abundant clean electricity for Europe from vast concentrating solar power (CSP) plants in the deserts of North Africa and the Middle East. But after five years attempting to turn theory into practice, the consortium formed in 2009 is effectively dead in the water after being abandoned by the majority of its shareholders. It was planned the infrastructure would meet as much as 15% of Europe's electricity needs by 2050. However, in October 2014 companies chose not to renew their contracts as part of the consortium.  link

July 2013: Desertec in trouble.
The Desertec Foundation statement pointed out that it rather than Dii is the “sole owner” of the “Desertec” brand name and concept, raising questions over Dii's ability to continue functioning without the foundation's support. It was unclear where the foundation’s decision to leave Dii will leave the consortium. link

Desalination traditional (energy inefficient) or solar alternative. Desalination removes unwanted minerals from saltwater so it can be used for drinking or agriculture

May 2016: Countries are turning to solar power to turn saltwater into drinkable water. Saudi Arabia uses around 300,000 barrels of oil every day to desalinate seawater, providing some 60% of its fresh water supply. That’s not sustainable. Finding a way to produce fresh water without burning fossil fuels is critical not just for the desert countries of the Middle East but for a growing number of places around the world. The new Al Khafji plant in Dubai will produce nearly 16 million gallons of fresh water a day, enough to supply the local population. The Spanish solar company Abengoa, which is helping build the plant calls it “the world’s first large-scale desalination plant to be powered by solar energy.” Unfortunately, solar-powered desalination is expensive: as much as three times the cost of water from grid-powered plants, according to the World Bank. Desalination plants need to run 24 hours a day, requiring expensive battery packs to supplement solar power when the sun’s not shining. Thanks to increased efficiency and the falling price of solar power, costs are expected to fall rapidly: from more than $50 per 1,000 gallons today, in the Middle East, to half of that by midcentury. But that’s still likely too much to make solar-powered desalination economically viable without government subsidies, even in places such as the Middle East that are optimal for solar power. link

July 2015: Californian compant explores solar desalination. WaterFX’s technology has several advantages over traditional desalination plants, including “not contributing to climate change,” cleaning up local salty, toxic irrigation drainage, and being more cost-effective., probably one-fourth the cost of conventional desalination. link

Other technical news

June 2016: Is 13% solar energy by 2030 possible? The global share of electricity generated by solar power could leap from 2% in 2016 to 13% by 2030 as falling cists drive investments around the world, according to a study by IRENA. Solar capacity leapt from 177 gigawatts in 2014 to 227GW in 2015, driven largely by rapid expansion across the US, China and Japan. In contrast, renewables growth in the EU has markedly slowed. link

August 2015: New ‘green’ antenna could double solar panel efficiency. Scientists from the University of Connecticut have developed a new type of antenna that could facilitate twice the amount of efficiency in existing solar panels which usually only capture 11 to 15% of the available energy. The antenna collects much more of the blue photons of the light spectrum than existing devices do. The key to the new technology is organic dye and while that process might sound complicated, it's actually not too difficult or expensive to do. What's more, the materials involved are compostable and kind to the environment if they need to be abandoned. link

June 2014: Producing cheaper, non-toxic solar cells. Solar power is typically thought to be among the cleanest of energy sources, but manufacturing solar cells is quite toxic. Currently, the most popular way to harness solar energy is through large, thick silicon plates that convert sunlight to electricity. But these iconic panels are expensive and inflexible. The cheaper alternative, thin film solar cells are unpopular for another reason: toxicity. To work effectively, the semiconductor cadmium telluride, which composes a layer of a popular kind of thin-film solar cell, must be treated with a chemical called cadmium chloride. But cadmium chloride is so toxic it cannot be leaked into the water supply without poisoning generations of fish. It is widely believed to be poisonous to humans as well.  A new study points to a safer and cheaper method, using an ingredient that is also used to make tofu. They found that magnesium chloride – a nontoxic compound derived from naturally occurring saltwater – worked just as well as its toxic counterpart. Furthermore, the natural compound costs only $0.001 per gram industrially, while the cadmium chloride costs $0.30 for the same amount.  link

August 2015: The Solar Sunflower – harnessing the power of 5,000 suns. The Solar Sunflower is a Swiss invention assisted by IBM. Combining both photovoltaic solar power and concentrated solar thermal in one neat package, efficiency around 80% is possible. The problem is, focusing the power of 5,000 suns on a single point brings heat to 105C., which needs a clever cooling system which is solved by a hot-water cooling technology. Cost is the next hurdle.  link

March 2014: Massive mirrored dishes could make solar cheaper for all. So much sunlight hits the Earth each day that the world’s entire electricity needs could be met by harvesting only 2% of the solar energy in the Sahara Desert. Of course, using solar power as the world’s only energy source hasn’t been possible yet, in part because solar equipment is expensive to make (and getting the power out of the desert would be no easy feat, either). But researchers at IBM think they’re one step closer to making solar universally accessible with a low-cost system that can concentrate the sunlight by 2,000 times. The system uses a dish covered in mirrors to aim sunlight in a small area; as the sun moves throughout the day, the dish follows it to catch the most light. Other concentrated solar power systems do the same thing, but quirks of this design make it much more efficient: A typical system only converts around 20% of the incoming light to usable energy, while this one can convert 80%. link

November 2009: Solar power could be produced cheaply in specially designed optical fibres, say researchers. Optical fibres could conduct sunlight into a building's walls where the nanostructures would convert it to electricity. link

When the sun doesn't shine - early solutions to storage. 

April 2009: Solar power can be used to generate electricity nearly round-the-clock. Engineers can now use molten salts to store the heat from solar radiation many hours after the sun goes down and then release it at will to drive turbines. This is a significant advance in the decades-old technology of solar thermal power production, which has traditionally used mirrors to heat water or oil to generate electricity-producing steam. link   April 2010: Giant gravel batteries could make renewable energy more reliable. Wind and solar power are often criticised for being too intermittent, but Cambridge researchers could change that. link 

September 2010:Spray-on solar cells make windows generate electricity.  The technology, which is called the Solar Window, aims to provide solar energy to building facades by spraying an electricity-generating coating on to glass. During the demonstration, the researchers compared the cost of the SolarWindow technology to traditional rooftop solar systems saying that the SolarWindow technology provides up to three times more savings in electricity costs. link   

Floating solar

June 2016: Floating solar a win-win solution for drought-stricken areas. Installing floating solar photovoltaic arrays, sometimes called “floatovolics” can produce renewable energy while shielding significant expanses of water from the hot desert sun. Floatovoltaic projects are now being built in places as diverse as Australia, Brazil, China, England, India, Japan, South Korea, and California. And nowhere could they prove as effective as on lakes Mead and Powell, the two largest man-made reservoirs in the US. For example, if 6% of California’s Lake Mead’s surface were devoted to solar power, the yield would be at least 3,400MW of electric-generating capacity, substantially more than the Hoover Dam’s generating capacity of 2,074 megawatts. link

Feed in tariffs and municipal lending schemes

May 2013: Feed-in-Tariff (FIT). Historically, FITs have been associated with a German model in which the government mandates that utilities enter into long-term contracts with generators at specified rates, typically well above the retail price of electricity. In the United States, where FITs are comparatively new, FITs or similarly structured programs are mandated to varying degrees in a limited number of states. However, a different model has also emerged in which utilities independently establish a utility-level FIT, either voluntarily or in response to state or local government mandates. A FIT is a performance-based incentive rather than an investment-based incentive, and in that respect is more similar to production tax credits and the renewable energy credits of an RPS market than to investment tax credits or other investment subsidies. In the United States, FITs are typically used in combination with one or more of these other incentives. link

April  2011: In Oakland, a creative strategy for financing the city's solar roofs.   link

December 2015: Community solar option. More than three-quarters of households in the U.S. are unable to install a rooftop solar system on their own home. But for residents in at least 24 states, according to a June report, community solar gardens are emerging as an option. Power generated by community solar in the U.S. is predicted to more than double between 2015 and 2016, as more states, utilities and companies get on board. link

August 2013: California organization makes solar energy affordable to those unable to finance. California-based GRID Alternatives installs solar systems on low-income households in California, Colorado and soon, in New York and New Jersey. The organization has installed 3,500 solar systems in California so far, projects that according to the organization have saved the homeowners $80 million in energy costs and will result in the reduction of 250,000 tons of greenhouse gasses over their lifetimes. Once the solar system is installed, the homeowner pays GRID two cents for every kilowatt-hour that the solar panels produce, which typically results in energy bill savings of 80%.  link

June 2011: Google invests $280 million for home solar roofs. Search giant Google is investing $280 million in SolarCity, a company that leases out solar panels to home owners. The new fund will give SolarCity the capital it needs to create more reasonable financing options for home owners interested in planting solar panels on their roofs and don’t necessarily have the cash to buy panels outright. The leases for the residential solar panels can last upwards of 15 years. SolarCity is currently the number two provider of residential solar panels behind SunRun. SolarCity has a market share of around 14%of the leasable solar panel market, while SunRun has a market share of around 28%. A study done by the University of California at Berkeley found that home values increase with solar panels installed. link  [In 2005 27 megawatts of residential photovoltaic were installed in the U.S. and 58 MW by 2007. By 2010  264 MW were installed according to the Solar Energy Industries Association.]

A New York Times article (March 14, 2009) cites an example where a $ 62,000 solar system was installed and is repaid, with interest, over 20 years as part of property taxes.

February 2010: Texas utility (TXU Energy) with two million customers, is making it possible for homeowners in the Dallas area to lease or buy rooftop solar-power systems in one of the first programs of its kind. Texas’s abundant sunshine, high air-conditioning costs and huge subdivisions make the state a natural solar market. “It’ll start off small, but over next five years, Texas could become one of the largest solar markets in the country.  link


August 2011: Large solar arrays concern for desert animals.
Builders of large solar array farms in Israel's Negev region and in places like California's Mojave Desert have had ongoing problems with nature lovers, environmentalists, and Native American Tribes. A recent study conducted by Israel's Nature and Parks Authority indicates that building giant solar array farms could be fatal to thousands of wild animals that live in the fragile ecosystem of these desert regions. link

European Photovoltaic Industry Association.

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