Friday, June 18, 2010
The solar water heater gained popularity at this time in Florida, California, and the Southwest. The industry started in the early 1920s and was in full swing just before World War II. This growth lasted prior to the mid-1950s when low-cost propane became the primary fuel for heating American homes.
The public and world governments remained largely indifferent to the possibilities of solar technology before oil shortages of the1970s. Today, people use solar technology to heat buildings and water and also to generate electricity.
How we use solar energy today ?
Solar energy is employed in a number of different ways, of course. There are two very basic forms of solar power:
* Solar thermal energy collects the sun's warmth through one of two means: in water or in an anti-freeze (glycol) mixture.
* Solar photovoltaic energy converts the sun's radiation to usable electricity.
Let us discuss the five most practical and popular methods solar power can be used:
1. Small portable solar photovoltaic systems. We see these used everywhere, from calculators to solar garden products. Portable units can be used for everything from RV appliances while single panel systems are used for traffic signs and remote monitoring stations.
2. Solar pool heating. Running water in direct circulation systems via a solar collector is a very practical solution to heat water for your pool or spa.
3. Thermal glycol energy to heat water. In this method (indirect circulation), glycol is heated by natural sunlight and the heat is then transferred to water in a hot water tank. This process of collecting the sun's energy is much more practical now than ever before. In areas as far north as Edmonton, Alberta, solar thermal to heat water is economically sound. It can pay for itself in 3 years or less.
4. Integrating solar photovoltaic energy into your home or office power. In most parts of the world, solar photovoltaics is an economically feasible way to supplement the power of your property. In Japan, photovoltaics are competitive with other kinds of power. In america, new incentive programs make this form of solar energy ever more viable in many states. An increasingly popular and practical way of integrating solar energy into the power of your home or business is through the usage of building integrated solar photovoltaics.
5. Large independent photovoltaic systems. For those who have enough sun power at your site, you could possibly go off grid. You may also integrate or hybridize your solar power system with wind power or other forms of sustainable energy to stay 'off the grid.'
How do Photovoltaic panels work ?
Silicon is mounted beneath non-reflective glass to produce photovoltaic panels. These panels collect photons from the sun, converting them into DC electric power. The power created then flows into an inverter. The inverter transforms the energy into basic voltage and AC electricity.
Solar cells are prepared with particular materials called semiconductors such as silicon, which is presently the most generally used. When light hits the Photovoltaic cell, a certain share of it is absorbed inside the semiconductor material. This means that the energy of the absorbed light is given to the semiconductor.
The power unfastens the electrons, permitting them to run freely. Pv cells also have one or more electric fields that act to compel electrons unfastened by light absorption to flow in a specific direction. This flow of electrons is a current, and by introducing metal links on the top and bottom of the -Photovoltaic cell, the current can be drawn to use it externally.
What are the benefits and drawbacks of solar technology ?
Solar Pro Arguments :
- Heating our homes with oil or propane or using electricity from power plants running with oil and coal is a reason behind climate change and climate disruption. Solar power, on the contrary, is clean and environmentally-friendly.
- Solar hot-water heaters require little maintenance, and their initial investment could be recovered within a relatively limited time.
- Solar hot-water heaters can work in almost any climate, even just in very cold ones. You just need to choose the best system for your climate: drainback, thermosyphon, batch-ICS, etc.
- Maintenance costs of solar powered systems are minimal and the warranties large.
- Financial incentives (USA, Canada, European states…) can aid in eliminating the cost of the first investment in solar technologies. The U.S. government, as an example, offers tax credits for solar systems certified by by the SRCC (Solar Rating and Certification Corporation), which amount to 30 percent of the investment (2009-2016 period).
Solar Cons Arguments:
- The initial investment in Solar Water heaters or in Solar PV Electric Systems is greater than that required by conventional electric and gas heaters systems.
- The payback period of solar PV-electric systems is high, as well as those of solar space heating or solar cooling (only the solar warm water heating payback is short or relatively short).
- Solar water heating do not support a direct in conjunction with radiators (including baseboard ones).
- Some hvac (solar space heating and the solar cooling systems) are very pricey, and rather untested technologies: solar ac isn't, till now, a really economical option.
- The efficiency of solar powered systems is rather influenced by sunlight resources. It's in colder climates, where heating or electricity needs are higher, that the efficiency is smaller.
Written by Guest Writer Barbra Young
Watching baseball’s first quadruple play was strange. Seeing Wal-Mart go green is stranger still.
First the baseball: The scene was a game of T-Ball, where everyone bats every inning, regardless of the number of outs.
The bases were loaded when a line drive ended up in the glove of the pitcher. While he wondered how it got there, all the runners took off without tagging up. The pitcher ran to third, then second, then first.
We kept counting the number of outs and they did not add up. First in our heads: That doesn’t make sense. Then on our hand: That’s crazy. Then our other hand: It kept adding up to four outs. It took us a while to believe what we saw right in front of us.
And now Wal-Mart, the original Black Hat, is going green. Or better said, sustainable. Let that sink in because it is true. Big time.
So much so that Treehugger.com says It “could end up being one of the biggest motivators to make truly ‘green’ products ever.”
As in history of the world.
Wal-Mart has made believers out of not just the biggest environmental organizations in the world — like the Environmental Defense Fund and the World Wildlife Federation — but also Wal-Mart’s suppliers.
It started five years ago when Wal-Mart announced three goals: 1) 100 percent renewable energy; 2) Zero waste; 3) Sustainable products.
Wal-Mart stores have already gone sustainable on dozens of fronts from shipping to selling to storing to recycling. Last year, Wal-Mart saved 4.8 billion plastic shopping bags. That’s how they roll in Bentonville: Big.
Even the combined efforts of 8400 stores with two million associates doing $400 billion in sales every year was not enough: Wal-Mart figured out 90 percent of the carbon was coming from its supply chain. So it reached down to all its 100,000 vendors — and their vendors and their vendors — and told them that reducing carbon footprints — reducing energy — will save money.
Everyone knows that is what Wal-Mart is all about.
“And vendors are listening,” said Tom Rooney, CEO of SPG Solar in Novato, California, one of the largest solar installers in the country. “We are seeing renewed and intense interest in industrial- and commercial-scale solar because of Wal-Mart and Proctor and Gamble and other companies are showing their suppliers how to change their shipping, packaging, storing, selling, heating, cooling, disposing, recycling and other practices to squeeze energy out of the supply chain and save money. And solar is a big part of that.”
Not that many need much coaxing: Financial incentives for solar today are so strong that many companies are essentially getting free energy — and more — by buying a new solar array from the money they will save from lower energy bills. And having a big chunk left over.
Now on top of that, the largest companies in the world are saying solar and other renewables have to be a part of their supply chain. By some estimates, 1 in 3 dollars worldwide is associated with a company that does business with Walmart. So, if you shift Walmart and its suppliers, the global economy shifts with it, says R. Paul Herman at hipinvestor.com. Or as the New York Times puts it: “because of its size and power, Wal-Mart usually gets what it wants.” And Wal-Mart wants renewable energy.
Earlier this year, Wal-Mart sent its vendors a 15 part questionnaire to determine what their companies were doing to become more sustainable. Also leading the effort is Wal-Mart’s “Sustainabilty Index.”
Scholars from around the world are gathering at the Universities of Arizona and Arkansas to create this new measure of the energy created — and wasted — during the life cycle of a product found at Wal-Mart. It won’t be ready for at least another year.
“But that doesn’t matter,” says Rooney. “No one is fighting Wal-Mart or complaining about the reporting that this new index requires. Just the opposite: They are racing to out do each other, and surpass Wal-Mart’s expectations. Right now. Not next year.”
And why not:
In May, the world’s largest consumer product company, Proctor and Gamble, announced its own, similar, sustainability program for its vendors. Joining IBM, GE, and other corporate giants on the sustainability train.
The results are already showing up on the bottom line:
“Perhaps more than any other company, Wal-Mart has pursued this approach” said the Harvard Business Review of Wal-Mart’s new vision of sustainability. “The payoffs are already showing up: One of the Sustainable Value Networks, tasked with fleet logistics, came up with a transportation strategy that improved efficiency by 38%, saving Wal-Mart more than $200 million annually and cutting its greenhouse gas emissions by 200,000 tons per year.”
Wal-Mart: Not just for beating up anymore. Or maybe we are just seeing the world’s first quintuple play.
Article by Jim Fitzpatrick, a retired civil engineer and solar enthusiast.