The solar cell had its birth in 1873, as bars of selenium. When two British scientists, William Grylls Adams and Richard Evans Day, in 1876, exposed the bars to candlelight they discovered something totally new: that light, not heat, could directly generate electricity in certain materials such as selenium. Adams and Day called the current produced this way, “photoelectric.” But try as they may, no one could increase selenium’s low conversion of sunlight into electricity and scientists concluded that to realize the vision of solar cells powering the world would require finding a new photovoltaic material.
That came when the collaborative effort of Daryl Chapin, Calvin Fuller and Gerald Pearson at Bell Laboratories developed a photovoltaic device capable of converting enough sunlight directly into electricity to generate useful amounts of power. Their public display at Bell’s press conference on April 25, 1954 of a 21-inch Ferris wheel spinning round and round powered by the first watt of silicon solar cells presented to the world one of the most significant breakthroughs ever recorded in the history of solar energy and of electricity. The New York Times realized the importance of what its reporters saw, stating on its front page that the invention of the Bell silicon solar cell marked “the beginning of a new era, eventually leading to the realization of one of mankind’s most cherished dreams – the harnessing of the almost limitless energy of the sun for the uses of civilization.” US News and World Report speculated that the new solar cell “may provide more power than all the world’s coal, oil and uranium…[its] future is limitless.”
At the time of the Bell announcement in 1954, all the solar cells in the world delivered about one watt. Today, more than 100 billion watts of generating capacity of photovoltaics have been installed worldwide. This year not only marks the 60th anniversary of the silicon solar cell but also the beginning of reaching the Holy Grail solar scientists had only previously dreamed of – entering the Era of Grid Parity, where solar panels generate power at costs equal to or less than electricity produced by fossil fuels and nuclear. With the phenomenal growth of solar pv in the last several years and its future even brighter, the time is ripe to celebrate the founding of a technology that led Science magazine almost forty years ago to declare, “If there is a dream solar technology, it is photovoltaics - solar cells...a space-age electronic marvel at once the most sophisticated solar technology and the simplest, most environmentally benign source of electricity yet conceived.”
Join us to celebrate the 60th birthday of practical photovoltaics and the great growth in solar electricity it has sired.
The material for the blog and upcoming world-wide celebration comes from John Perlin’s recently published book, Let It Shine: The 6000-Year Story of Solar Energy. For more information on the book, see the Renewable Energy Blog post "Let It Shine." The celebration will kick off in Palo Alto, California on April 18, 2014, where guests will get to meet some of the great remaining original solar pioneers and hear from the Mayor of Palo Alto how the city is procuring all its power from solar and other renewables. For more details, go to PV60.org.)
The increased use of glass during the seventeenth and eighteenth centuries reawakened the awareness of its ability to trap solar heat. That no one ever thought of finding out just how much solar heat glass could trap surprised the Swiss polymath Horace B. de Saussure. He therefore built in 1767 a rectangular box from wood, insulated with black cork and covered the top with three sheets of glass. When he tilted the box toward the sun, the temperature inside the solar hot box rose above the boiling point of water. Because of the large amount of solar heat the device retained, it became known as a solar hot box. Saussure cooked inside the hot box the first recorded solar meal. The solar hot box became popular among experimental scientists in the eighteenth and nineteenth century.
Samuel Pierpoint Langley, head of the Smithsonian in the latter part of the nineteenth century, built a solar hot box and took it with him on an expedition to Mount Whitney. He melted snow inside the box for drinking water despite freezing temperatures outside. Renowned English astronomer Sir John Herschel amused passersby in South Africa by cooking meals in his solar hot box. “On one occasion,” he wrote, “a very respectable stew was prepared and eaten with no small relish by the entertained bystanders.” Reading Herschel’s account led fellow nineteenth-century astronomer Jacques Babinet wonder why, “In countries in which the atmosphere is always clear, as in Egypt, Arabia and Persia, where fuel is scarce and dear, people have never thought of utilizing the concentrated rays of the sun under glass for tasks where heat is needed, such as cooking.”
The solar hot box design became the prototype for solar thermal collectors used to heat water and homes.
Saussure’s solar hot box also models with amazing precision the dynamics of global-warming. . In the early 19th century, the French physicist Joseph Fourier was the first to notice the similarity between de Saussure’s hot box and what might happen should the atmosphere somehow lose its transparency to heat generated by solar radiation after reaching the earth, as most climate scientists suspect it does as humans emit greater amounts of greenhouse gases.
Fourier suggested that, like the glass covers, our atmosphere allows the short wave radiation of sunlight to easily pass through. But when the sunrays hit the earth, just as they do at the bottom of the hot box, they turn into longer heat waves, which cannot easily escape through the glass or a carbon-saturated sky, causing the heat to accumulate inside the box and on a planetary scale in the lower levels of the atmosphere. The clouds of carbon dioxide surrounding Venus provide us with a living example of the ultimate solar hot box where temperatures at the planet’s surface hover at around 890 degrees Fahrenheit.
This post summarizes the author’s Chapter 6 of Let It Shine: The 6,000-Year Story of Solar Energy.
Photo from Smithsonian Institution Archives
Before the adjective “green” was used to describe the modern environmentalist movement, the color had a more monetary association. Hey, green may be the color of nature, but it’s also the color of money, and for your average person, the later plays a more significant day-to-day role than the former. But that doesn’t mean that the two are mutually exclusive! Take solar power, for example. It’s a clean, renewable, and—for all intents and purposes—inexhaustible energy source that can also just happen to save you loads of cash. In essence, solar power can help you go green, no matter which definition you happen to find more important. Here’s how:
Reduced Energy Costs
In 2009, the U.S. Energy Information Administration released a Residential Energy Consumption Survey. In it, they identified that the average United States homeowner ends up spending approximately $2,000 on home energy costs. Of course, those figures were gathered half a decade ago, so you can bet that the cost has only gone up since then. The point is, there’s probably a few things that come to mind when you consider what you could do with an extra $2,000 every year. The reason energy costs so much is that it’s difficult and expensive to generate. 44% of U.S. electricity comes from -burning plants (which also happen to be the biggest cause of air pollution in the country), with the other 36% divided between wind power, geothermal power, hydroelectric power, etc. All of these methods require resources, maintenance, and scores of employees to be able to function, and the person who gets to pay for it all is you. But, by switching over to home mounted-solar paneling, you effectively eliminate (or at least substantially reduce) your dependence on the city grid. Of course, the panels themselves are still somewhat expensive to purchase, which is why many individuals are taking a different approach. Vivint, Solarcity, and other major solar companies are now offering rentable solar panels. These companies are leasing solar power to customers for a fraction of what it would cost to get energy from the city.
Believe it or not, the government is just as interested in preserving the planet as anyone (you could say that they have a vested interest in it). As such, they’re currently willing to offer monetary incentives to help motivate the American population into using clean energy sources. These incentives often take the form of tax credits, which allow a recipient to reduce the total amount of taxes that need to be paid. Tax credits may be offered by both the federal government, as well as state government, and can make a big difference to your bank account once April 15th rolls around. So, if you decide to throw your hat in with solar power, you might be able to keep a bit more of your hard-earned cash come tax season.
Improved Home Value
Anything that you do to your home will affect its overall worth, and solar panels are no exception. However, the question is this: Is the increased value enough to offset the initial installation costs? Well, it’s impossible to say for sure, given that much of it depends on what potential home buyers are willing to pay, but the outlook is pretty good. A report by the National Bureau of Economic Research suggests that (especially in more liberal states), homeowners can recuperate up to 97% of their initial solar investment costs, and that doesn’t account for the other associated energy savings that come with solar power. This means that whether you want to sell your home or live in it for the rest of your life, you’ll be well rewarded if you’re willing to invest in solar power.
So, whether you’re more interested in keeping the planet green, or in lining your wallet with green, solar power is the way to go. Of course, you may have to spend a bit of green upfront, but just consider it an investment in the future—both for your bank account and for your planet.
This winter, I’ve been corresponding with a Cuban colleague who works for Cuba Energia, an energy information center in Cuba. He tells me that the Government has decided to introduce modern, efficient induction cooking to the country by offering 125,000 units for sale to residents countrywide. So, why should we be interested in what Cuba is doing?
Cuba’s Sustainable Living Practices
People who live on islands tend to have a better handle on the concept of finite resources in general. But after the collapse of Soviet Union, their main trade ally, and due to the ever intensifying US blockade, Cubans had to learn how to produce basic requirements such as food, medicines, and energy, both locally and sustainably. In the spring of 2011 I had the opportunity to travel to Cuba with a group of energy professionals to see first-hand how they were managing these efforts. Read more about this in The Homeowner’s Energy Handbook.
Due to the hardships endured, the Cuban people were able to reduce their energy consumption by about 50 percent over a four year period. This was not necessarily an altruistic goal, but one of necessity, and ultimately an effort that brought the island nation together as a large community. They learned some hard lessons that the rest of us can use to our advantage. The Cuban government made efficient products available to everyone for free or at much reduced prices, including lights, refrigerators, pressure cookers, and bicycles. And now, possibly, induction cook stoves.
How Induction Cooking Works
Induction cook stoves have no heating element and so do not get hot. They work by generating a high frequency (20 to 60 kilohertz) electric current, and inducing a magnetic field into the cookware itself. The metallic cookware receiving this induced energy is essentially the second “conductor” in this electromagnetic “circuit”, and the internal resistance of the cookware is what creates the heat. The type of pots and pans you use will have an effect on efficiency, and only cookware with iron in it will work with today’s induction cook tops. If in doubt, check the pot or pan in question with a magnet. If it’s magnetic, it should work well with induction cooking.
Pros and Cons of Induction Cooking
The lack of a conventional and relatively inefficient heating element or burner makes kitchens safer and cooler. Users report faster heating times, and because the cookware itself becomes the source of heat for the food it contains, more even heating can be expected. Other benefits include easy to clean surfaces, precision temperature control, and very low temperature settings. If you use a pressure cooker, beware that using an induction cook top requires some modifications to your approach.
Induction cook stoves are still relatively expensive and so not yet very popular except in high end home and commercial kitchens. Finding good energy use information is difficult, as I’ve not yet seen any high quality studies on energy consumption comparisons; perhaps the first will come from Cuba. Anecdotal evidence from users suggests that they are quite fast at heating, but the induction elements have the same power requirements as conventional electric ranges. This combination suggests higher efficiency and lower cooking costs, but one older study indicates marginal efficiency improvements over conventional electric stoves (84% vs 74% energy transfer efficiency). Savings estimates may be further reduced due to standby loads that will vary with the type and brand. Commercial kitchens may enjoy the benefit of much reduced space cooling requirements, something no chef or restaurant accountant would complain about!
Possible Health Concerns
One concern that does not seem to be resolved yet is the potential health risk of stray magnetic fields which can occur if the pot does not completely cover the induction unit. The risk can range from interference with pacemakers to exceeding human EMF exposure limits.
I’ll be keeping in touch with Cuba Energia, and hope to report back in the future as to the outcome of Cuba’s efficient cooking program.
Paul Scheckel is the author of The Homeowner’s Energy Handbook, your guide to getting off the grid”.
Photo from Newsroom.Electrolux.com
1.3 billion people live without access to electricity. Of this, eighty percent reside in rural areas and are considered as individuals at the bottom of the pyramid (BoP). Day in and day out they rely on energy sources like kerosene, which is both expensive and harmful to use. They have been waiting for the electricity grid to arrive—and they’ll continue to wait for decades.
In the last five years, falling costs of solar technology have made solar economically viable without subsidies for off-grid communities. This market opportunity is driving entrepreneurs to quickly establish themselves in the space. As they continue to improve their product offering, distribution and after-sales networks for solar products, market demand too is growing. It’s becoming clearer every year that solar technology has the potential to leapfrog the electricity grid in many developing countries where electrification rates are still low.
How can businesses keep up with this potential solar growth? Hint: it’s all about the customer.
Solar Is Not Only About Lamps
The story of solar lights lighting up homes is popular because it’s powerful, easy to tell, and its impact simple to grasp. The price point for solar lights is also affordable for low-income communities and has one of the quickest payback periods for any investment. In a nutshell, it’s easy to only focus on solar lights when talking about solar for the energy poor.
But we have to recognize that solar lamps are just the starting point, and several years have gone by since the first wave of social enterprises selling solar lamps took off. In that time, affordable solar technology for off-grid communities has advanced far beyond just powering single LED lights at a minimum to providing homes with enough energy to switch on multiple lights, power a radio while also charging more than one phone, all at the same time. This is what a solar home system (SHS) does. While more expensive than a solar lamp, it becomes affordable with appropriate financing options in place. To illustrate, SHS sold by Uganda-based Fenix International costs $16 upfront for the unit, and then 40 cents a day to use. Those numbers are close to or maybe even under what the one billion plus living without electricity are already paying for kerosene, so switching to solar has truly become affordable for all.
Innovation in Solar Continues To Be Driven by What the Customers Want
The key takeaway from the evolution of solar technologies designed for off-grid communities is that major improvements in quality have heavily relied (and will continue to rely on) customer feedback. For example, in the early days when off-grid solar took the spotlight—which was just several years ago—many solar products were designed to look more like a traditional desk lamp with very basic interface, sometimes with nothing more than one power button to switch on the light. Soon enough, the design was improved to accommodate how customers actually use the light; some examples are a portable mode for external use, a charging-effectiveness indicator to know when the battery is fully charged and multiple light settings to fit various uses.
Another major added feature to solar lamps that was driven by customer feedback is the mobile phone charging capability. There are about 600 million mobile phone users globally that have no good way to charge their phones because they live in unelectrified areas. Many of them must pay transportation and charging costs to power their phones in unconventional ways, like with a car battery. It’s not surprising then that a solar lamp that can charge mobile phones would be in high demand. In fact, here are 5 reasons why the CEO of SunFunder thinks the off-grid solar revolution will be driven by cellphones, and they are still relevant.
Solar customers today have larger aspirations. Having experienced solar-powered lights and phone charging, they are now demanding solar power for larger appliances like television and refrigerators. A number of companies are undertaking the challenge of upgrading their products and pricing plans to meet these aspirations. SolarNow in Uganda is one such company. SolarNow’s modular approach allows customers to add DC LED television as an accessory to their solar home system packages, which start at 50W with a maximum capacity of 500W. This year, SolarNow expects to add a DC refrigerator to their product catalog. Coupled with a payment plan, SolarNow’s customers can now afford a modern, aspirational energy lifestyle (and even watch the World Cup this year!), which leads me to the last point.
End-User Financing Is the game-Changer for Off-Grid Solar
One of the main barriers for low-income communities to adopt solar technology is the upfront cost required. We’ve seen, however, how companies like Fenix International and SolarNow can remove this barrier by offering end-user financing plans, and there are many ways to do so.
Some solar companies partner with Savings and Credit Cooperatives (SACCOs) to sell products through their member networks and existing lending infrastructure. Other companies are innovating around end-user finance to integrate mobile money payments and remote control of systems; thus if a customer hasn’t paid via their cellphones, the system can be switched off remotely. These include Mera Gao Power, M-Kopa, Angaza Design and Off:Grid Electric.
With all these end-user financing systems in place, it is the companies that must bear the upfront cost burden, thereby increasing the need for working capital finance. Banks, however, are not reliable sources of finance due to the risk profile associated with off-grid solar businesses and the novelty of the space. Even if banks do offer loans to these businesses, they charge exorbitantly high interest rates. In fact, lack of access to finance is the number one barrier cited by off-grid solar companies in Lighting Global’s 2013 reportOverview of Off-Grid Lighting Market in Africa.
This lack of access to finance for off-grid solar businesses is why the company I work for, SunFunder, exists. We are a solar finance business connecting investors with high-impact solar projects benefiting low-income communities that live without electricity in Africa, Asia, and Latin America. We provide much needed short-term working capital and inventory loans to off-grid solar companies, including Fenix International, SolarNow and Angaza Design. We can offer those businesses the customized debt financing solution they need by sourcing capital from two types of investors. The first type is the casual lender who makes loans as little as $10 on SunFunder.com and gets their $10 (or more) repaid in one year. The other type is the accredited or institutional investor that invests in larger sums with more complex terms, but earns back their principal with an interest return.
The market for solar is not only driven by a tremendous unelectrified population; existing solar customers are also aspiring for more products to achieve a modern energy lifestyle. It is up to the companies in the market to deliver to their customers, and up to the global community to ensure that the companies have the financial opportunity to. Together through SunFunder anyone can participate in unlocking solar finance to propel an off-grid solar revolution.
Photos by Sameer Halai/SunFunder
Clergy in Path of Pipeline Urge President Obama
Reject Keystone XL on Moral Grounds
As court decision creates new obstacle, religious leaders voice opposition
SAN FRANCISCO – Faith leaders in the path of TransCanada’s proposed Keystone XL pipeline are joining colleagues across the country to urge President Barack Obama to reject the project in order to curb carbon emissions and protect God’s Creation.
“This is an issue of justice,” said Pastor Kyle Childress, whose Austin Heights Baptist Church lies 15 miles from the pipeline. “TransCanada is running over people, destroying God’s earth, and pouring out climate-changing carbon, all in the name of short-term profit – and expecting our communities to shoulder the burden.”
More than 150 clergy members have joined some 4,000 people of faith in signing a letter asking the president to stop the pipeline’s construction, adopt clean energy technologies and policies that will lead a global clean energy movement. Some of those faith leaders joined a telephone press conference today to mark the letter’s release.
“As people of faith, we share your conviction that we are commanded by God to care for our planet and that the failure to respond to the threat of climate change would betray our children and future generations,” the letter says, referring to the president’s State of the Union address.
The letter — penned by Interfaith Power & Light, a leading religious voice on climate change — coincides with the close of the State Department’s last public comment period before the Administration makes a decision on the Keystone XL pipeline. It would carry oil from Canadian tar sands through the United States to refineries in Texas.
Last week, in a move that could further delay the beleaguered project, a Nebraska judge ruled the law giving the governor pipeline siting authority illegal. The judge also declared "null and void" the law's permission to TransCanada to claim landowner's property in the path of the pipeline on the basis of eminent domain, which is normally used by the government to take private property for public use.
"The people of Nebraska love their land and have made their voices clear: stop the TransCanada pipeline,” said Rev. Kim Morrow of First-Plymouth Congregational Church in Lincoln, Nebraska. “We must protect the Ogallala Aquifer and the sensitive Sandhills region of our state. Our ranchers and farmers have been affronted by the bully tactics used to try to seize land that has been in their families for generations. This pipeline holds no benefits for Nebraska, and instead just risks jumping from the frying pan into the fire with climate change."
Clergy members across the country agree.
“As a man of faith, Obama should recognize this moment as an opportunity to protect God’s creation and shape his legacy around the long-term energy strategy of America,” said the Rev. Dr. Joel Hunter of Northland Church in Florida, one of the nation’s largest and fastest-growing congregations. “This is a pivotal moment for the president.”
“People of faith have a responsibility to preserve God's gift of clean air, water and land,” added the Rev. Sally Bingham, president and founder of Interfaith Power & Light. “The Keystone Pipeline is too great a risk to that call to be gardeners. We were put in the garden to till and to keep. This dangerous pipeline jeopardizes the health of the garden and all living things. We find it sinful that financial gain is being considered more important than preserving the air, water and land for future generations. In other words, that money can trump moral responsibility.”
Interfaith Power & Light (IPL) is a national organization with 40 state affiliates reaching 15,000 congregations advocating for climate protection, clean energy, and stewardship of Creation.
Air-source heat pumps are not exactly new to the world of air conditioning and the HVAC industry, and they are very different from ground-source heat pumps (their respective names refer the source of the heat to be gained and used). What is new however is the surge of interest in using air source heat pumps for heating in addition to cooling. This is primarily due to advances in technology that make heat pumps effective for heating in very cold climates (down to -15F), while also delivering exceptionally efficient cooling performance.
An air source heat pump is a modern appliance that extracts heat from one place and moves (or pumps) it to another, much like a refrigerator removes heat from its interior and out into the kitchen. Moving heat is much more efficient than generating it, so heat pump heating is more efficient and costs less than half as much to operate compared to conventional electric heat. Because it’s a pump, it can move heat in both directions – from indoors to out, or outside to inside. The happy result is that very high-efficiency heating and air conditioning are available through this single, integrated heating/cooling appliance.
Heat delivery, use of interior wall space, and the ‘quality’ of heat is similar to a single, central, wall or floor-mounted gas heater. There is also a small, quiet, outside unit. During the past two years, my company (Shelter Analytics) has been focused primarily on delivering energy efficiency services to condominium associations. The quiet operation and low profile of air-source heat pumps have made them ideal for the close-living environment and space constraints of condo owners in addition to single family homes.
Single or multi-head air source heat pumps are also called “mini-splits” or “ductless” air-conditioning and heating units. They are different from central heating and cooling systems because there is no duct-work for heating or cooling distribution. A single outdoor unit serves one or more indoor units which deliver conditioned air directly to the space (or zone) in which they live.
Currently, only single head systems (one indoor heat delivery unit) are available for cold climate heating, limiting their use to small dwellings, large rooms, or homes with open floor plans. Of course, a more efficient building envelope (good insulation and minimum air leakage) makes any heating system more effective. In fact, an efficient home equipped with solar panels and an air source heat pump can use solar energy for active heating and cooling. By late 2014, “multi-head” cold-climate heat pumps will be available offering greater flexibility. To be clear, multi-head systems are currently available that provide efficient heating and cooling in moderate climates where temperatures are consistently above the 0F mark.
The magic of a heat pump happens when a refrigerant (typically R-410A), is circulated through a copper tube within a closed loop between indoor and outdoor units. When the refrigerant is compressed, it becomes colder and able to absorb heat. As it warms, it changes phase from liquid to gas, ready to be compressed and cooled again. Smart controls tell the heat pump which direction to work, so that heat can be absorbed from, and delivered to, the right place (indoors or out) depending on your desired indoor temperature.
Ducts in a typical home are generally leaky and uninsulated. Efficiency gains with a heat pump are increased because there are no ducts through which conditioned air must travel. Additionally, ducted systems are difficult to split into zones, but a single or multi-head heat pump allows you to condition only the room, or rooms, desired.
There are currently only two cold-climate heat pumps available in the U.S. they are the Mitsubishi M-series and Fujitsu RLS2H, but more are likely on the way. It will be important to size units appropriately for your home and climate by having a heating contractor determine the heat load of your home.
For more energy efficiency and renewable energy solutions for your home, please read The Homeowner’s Energy Handbook: Your Guide to Getting Off the Grid by Paul Scheckel.