Green Hotels Use Solar Hot Water

More and more commercial operations are turning to renewable energy to green their practices to both save money and the environment. In fact, green hotels use solar hot water to significantly defray operating costs and energy usage.
We’ve written about solar hot water systems incorporated into breweries and dairies – both of which have high hot water demands. It shouldn’t be surprising that hotels and resorts that turn to solar hot water can really cut down on energy demands.
Consider that one of the largest components of hotel operating costs is hot water. Not only is it used by guests to take showers and shave, but significant amounts are demanded each and every day to wash towels and other linens, clean guest rooms and more.

Instead of relying on electricity, natural gas or oil, green hotels can now use solar hot water to maintain profit margins and avoid passing on energy cost increases to their guests. In fact, many properties can expect to save thousands of dollars each year as a result of installing solar hot water.
One company, SunMaxx, has a super solar hot water system for both residential and commercial use. In fact, they can help you develop a solar system to meet the needs of a hotel or resort, including pool and spa heating.
According to its website, a SunMaxx Solar Hot Water System can be used for:
Domestic Hot Water (laundry, cleaning, showers)
Solar Radiant Space Heating
In floor radiant heating
Baseboard radiant heating
Forced hot air heating
Solar Central Cooling / AC Systems
Solar Pool & Spa Heating
Snow / Ice Melting Applications
Sidewalks
Driveways
Parking Lots
Common Public Location

How do Solar Panels Work?

Whether on a solar-powered calculator or an international space station, solar panels generate electricity using the same principles of electronics as chemical batteries or standard electrical outlets. With solar panels, it's all about the free flow of electrons through a circuit.

To understand how solar panels generate electrical power, it might help to take a quick trip back to high school chemistry class. The basic element of solar panels is the same element that helped create the computer revolution -- pure silicon. When silicon is stripped of all impurities, it makes a ideal neutral platform for the transmission of electrons. Silicon also has some atomic-level properties which make it even more attractive for the creation of solar panels.

Silicon atoms have room for eight electrons in their outer bands, but only carry four in their natural state. This means there is room for four more electrons. If one silicon atom contacts another silicon atom, each receives the other atom's four electrons. This creates a strong bond, but there is no positive or negative charge because the eight electrons satisfy the atoms' needs. Silicon atoms can combine for years to result in a large piece of pure silicon. This material is used to form the plates of solar panels.

Here's where science enters the picture. Two plates of pure silicon would not generate electricity in solar panels, because they have no positive or negative charge. Solar panels are created by combining silicon with other elements that do have positive or negative charges.

Phosphorus, for example, has five electrons to offer to other atoms. If silicon and phosphorus are combined chemically, the result is a stable eight electrons with an additional free electron along for the ride. It can\'t leave, because it is bonded to the other phosphorus atoms, but it isn\'t needed by the silicon. Therefore, this new silicon/phosphorus plate is considered to be negatively charged.

In order for electricity to flow, a positive charge must also be created. This is achieved in solar panels by combining silicon with an element such as boron, which only has three electrons to offer. A silicon/boron plate still has one spot left for another electron. This means the plate has a positive charge. The two plates are sandwiched together in solar panels, with conductive wires running between them.

With the two plates in place, it's now time to bring in the 'solar' aspect of solar panels. Natural sunlight sends out many different particles of energy, but the one we're most interested in is called a photon. A photon essentially acts like a moving hammer. When the negative plates of solar cells are pointed at a proper angle to the sun, photons bombard the silicon/phosphorus atoms.

Eventually, the 9th electron, which wants to be free anyway, is knocked off the outer ring. This electron doesn't remain free for long, since the positive silicon/boron plate draws it into the open spot on its own outer band. As the sun's photons break off more electrons, electricity is generated. The electricity generated by one solar cell is not very impressive, but when all of the conductive wires draw the free electrons away from the plates, there is enough electricity to power low amperage motors or other electronics. Whatever electrons are not used or lost to the air are returned to the negative plate and the entire process begins again.

One of the main problems with using solar panels is the small amount of electricity they generate compared to their size. A calculator might only require a single solar cell, but a solar-powered car would require several thousand. If the angle of the solar panels is changed even slightly, the efficiency can drop 50 percent.

Some power from solar panels can be stored in chemical batteries, but there usually isn't much excess power in the first place. The same sunlight that provides photons also provides more destructive ultraviolet and infrared waves, which eventually cause the panels to degrade physically. The panels must also be exposed to destructive weather elements, which can also seriously affect efficiency.

Many sources also refer to solar panels as photovoltaic cells, which references the importance of light (photos) in the generation of electrical voltage. The challenge for future scientists will be to create more efficient solar panels are small enough for practical applications and powerful enough to create excess energy for times when sunlight is not available.

Solar energy changing lives in remote,backward Tharparkar region

Environment-friendly solar energy has changed the lives of several hundred households in Tharparkar, which remains one of the most backward regions of the country.

The Alternate Energy Development Board, Pakistan Poverty Alleviation Fund and Thardeep Rural Development Programme ñ a non-governmental organisation ñ have joined hands to launch the solar energy project in this arid region at a time when the country faces massive electricity shortage.

In a vast desert region like Tharparkar, where temperature hit a peak of 30-35 degrees Celsius even in winters and touches a high of over 50 degrees Celsius during summers, the scorching rays of sun are usually seen as a bane.

But for the first time, this immeasurable resource is being utilised like any other modern place of the world.

Solar energy is not just providing electricity to the mud-and-straw houses of remote villages, but also helps irrigate small patches of land.

“The electricity has changed our lives,” said Khanno, a 45-year-old farmer, who like most residents of this place uses only one name. “Electricity has extended our day. Now my children can study even after the sunset.”

The solar energy project, launched two years ago, has so far provided electricity to 16 villages at a cost of more than Rs100 million, including the villages of Kasbo, Rarko, Wadhanjowadhio and Oanjowadhio ñ all in Tharparkar district.

Riaz Rajar, an official of Thardeep Rural Development Programme, said that one panel costs around Rs700,000 to Rs800,000.

"We install at least eight such panels in a village, which is a one time investment," he said. "They generate enough electricity to illuminate 20 to 30 houses."

“Pakistan Poverty Alleviation Fund contributes 80 per cent of the funds and the remaining 20 per cent is raised by the local community,” Rajar said.

He said that electricity-run power pumps help pull water from 50 to 150 feet below the surface.

“Apart from drinking, this water is also used for irrigation through drip technique to save wastage and conserve this precious natural resource, which is scarce in this region.”

Scarcity of water in Tharparkar, bordering the Great Indian Desert, impacts the entire population, especially women, who had to walk miles to fetch two buckets of water from the wells.

But electric pumps have made their life easy.

Now solar energy is being used to pull water, which is stored in cement tanks.

Khanno, the farmer, said that thanks to electricity he now manages to cultivate onions and tomatoes on his two acres of once barren land.

According to SciDev, a London-based non-profit organisation, there is no shortage of solar energy across the world. Almost all the developing countries have enormous solar power potential, it said in a report.

Solar energy changing lives in remote,backward Tharparkar region

SOLAR TECHNOLOGY

The Solar Energy Technologies Program focuses on developing cost-effective solar energy technologies that have the greatest potential to benefit the nation and the world. A growing solar industry also stimulates our economy by creating jobs in solar manufacturing and installation.
Photovoltaics

The Photovoltaics subprogram aggressively funds a diverse set of PV technologies that have potential in many markets that will help solar electricity achieve grid parity.
Concentrating Solar Power

The Concentrating Solar Power subprogram is making CSP competitive in the intermediate power market and developing advanced technologies that will reduce system and storage costs through partnerships with solar companies and universities and national laboratories.
Systems Integration

The Systems Integration subprogram addresses the technical barriers to wide-scale deployment of solar technologies on the grid by funding solar companies to develop smarter technologies, supporting testing and demonstration at national laboratories and in the field, developing new codes and standards, and removing economic barriers.
Market Transformation

The Market Transformation subprogram works with cities, states, utilities, and other partners to address barriers to the widespread adoption of solar technologies and reduce the non-hardware costs associated with installation.

Photovoltaics

he U.S. Department of Energy works to provide clean, reliable, affordable solar electricity for the nation through its research programs in photovoltaic (PV) energy systems. The following pages explain the "how's" and "why's" of PV. Whether you are a student, builder, consumer, engineer, or researcher, there is something here for you.

Photovoltaic technology makes use of the abundant energy in the sun, and it has little impact on our environment. Photovoltaics can be used in a wide range of products, from small consumer items to large commercial solar electric systems.

Our goal is to ensure that photovoltaic energy systems make an important contribution to the energy needs of our nation and the world. In these pages, you will learn about DOE's R&D in photovoltaic energy systems.

Advancement in Solar Energy Technology

The atmosphere, oceans and land mass of the Earth absorbs enough energy from the sun in one hour to power the entire planet for one year. Surely we are clever enough to capture some of this magnificent force and use it to fuel our environment.
Solar energy and its use can be divided into two areas. Those are static or passive solar energy collection and dynamic, or perhaps better termed, kinetic solar energy collection and use.
An example of passive solar energy collection would be building a house so that the windows face the morning sun in colder climates. An even more rudimentary example would be that of an alligator sunning himself on the edge of the water. In both cases the sun’s energy is simply absorbed for warmth. And the simplest use of solar energy is as the very daylight we walk about in. Our Earth automatically uses the power of the sun in millions of ways. Not the least of which is photosynthesis by plants for production of oxygen for our atmosphere. Ours is an inherently rechargeable renewable world, provided we use our resources such as solar energy wisely.
To that end, we must examine dynamic solar energy collection for the production of warmth and light.
When you walk though almost any shopping mall built in the last twenty years you will probably notice a flood of bright natural light all around you. Most large malls and department stores are built with double paned insulated windows that allow light to enter yet keep heating or cooling locked inside. But what happens when the sun follows its arc away from those windows? Active solar lighting can use mirrors that track with the sun’s movement and then reflect light into fiber optic cable that can carry that light into any part of our same department store.

We can create transfer warmth through various forms of solar thermal energy. Since the 1950s it has not been uncommon to see simple glass paned boxes filled with copper pipes used to help heat water for swimming pools and boilers. These low temperature collectors are fine for space heating but there are far more effective ways to heat water with the sun’s rays and put that water to work.
High temperature parabolic shaped mirrors can heat water to far greater temperatures than made possible by our simple rooftop hot boxes. In fact bowl and trough type mirrors can boil water to steam which in turn uses a turbine to generate electricity for heating, air conditioning and general power supply. When properly applied, this concentrated solar power can supply 50% of the power needs for a modern factory. Concentrated Solar Power is one half of our method for creating electricity from the sun’s radiant energy.

he most commonly thought of use and form of solar energy conversion is that of relying upon solar voltaic cells. These solar cells are also called photovoltaic. First developed in the 1880s, photovoltaic cells rely upon the electronic reaction of certain key elements to the Sun’s rays so as to produce a tapable flow of electrons that are in turned used to create current flow. In short photovoltaic cells turn sunlight into energy. And lest we think we are so clever for figuring out how to do this, consider that plants have been turning sunlight into energy for millions of years.
Advances in the development of photovoltaic cells have increased drastically since the oil shortages of the 1970s. This is primarily due to development of silicon technologies. Crystalline silicon cells when working in conjunction with CSP (concentrated solar power) as supplied by parabolic mirrors have improved output from Photovoltaic cells by a factor of 50 since their more basic development in 1954. Increases in demand and subsequent increases in production have lowered the price of solar cells to the point that they are now almost competitive with wind power technology and like their low emissions wind counterparts are far less costly than nuclear power.
Development, deployment and economics

Solar Electric power as supplied by huge banks of photovoltaic cells is providing billions of watts of power throughout the world.

Thin film solar cells

The high cost of crystalline silicon wafers (they make up 40-50% of the cost of a finished module) has led the industry to look at cheaper materials to make solar cells.

The selected materials are all strong light absorbers and only need to be about 1micron thick, so materials costs are significantly reduced. The most common materials are amorphous silicon (a-Si, still silicon, but in a different form), or the polycrystalline materials: cadmium telluride (CdTe) and copper indium (gallium) diselenide (CIS or CIGS).

Each of these three is amenable to large area deposition (on to substrates of about 1 meter dimensions) and hence high volume manufacturing. The thin film semiconductor layers are deposited on to either coated glass or stainless steel sheet.

The semiconductor junctions are formed in different ways, either as a p-i-n device in amorphous silicon, or as a hetero-junction (e.g. with a thin cadmium sulphide layer) for CdTe and CIS. A transparent conducting oxide layer (such as tin oxide) forms the front electrical contact of the cell, and a metal layer forms the rear contact.

Thin film technologies are all complex. They have taken at least twenty years, supported in some cases by major corporations, to get from the stage of promising research (about 8% efficiency at 1cm2 scale) to the first manufacturing plants producing early product.

Amorphous silicon is the most well developed of the thin film technologies. In its simplest form, the cell structure has a single sequence of p-i-n layers. Such cells suffer from significant degradation in their power output (in the range 15-35%) when exposed to the sun.

The mechanism of degradation is called the Staebler-Wronski Effect, after its discoverers. Better stability requires the use of a thinner layers in order to increase the electric field strength across the material. However, this reduces light absorption and hence cell efficiency.

This has led the industry to develop tandem and even triple layer devices that contain p-i-n cells stacked one on top of the other. In the cell at the base of the structure, the a-Si is sometimes alloyed with germanium to reduce its band gap and further improve light absorption. All this added complexity has a downside though; the processes are more complex and process yields are likely to be lower.

In order to build up a practically useful voltage from thin film cells, their manufacture usually includes a laser scribing sequence that enables the front and back of adjacent cells to be directly interconnected in series, with no need for further solder connection between cells.

As before, thin film cells are laminated to produce a weather resistant and environmentally robust module. Although they are less efficient (production modules range from 5 to 8%), thin films are potentially cheaper than c-Si because of their lower materials costs and larger substrate size.

However, some thin film materials have shown degradation of performance over time and stabilized efficiencies can be 15-35% lower than initial values. Many thin film technologies have demonstrated best cell efficiencies at research scale above 13%, and best prototype module efficiencies above 10%. The technology that is most successful in achieving low manufacturing costs in the long run is likely to be the one that can deliver the highest stable efficiencies (probably at least 10%) with the highest process yields.

Amorphous silicon is the most well-developed thin film technology to-date and has an interesting avenue of further development through the use of "microcrystalline" silicon which seeks to combine the stable high efficiencies of crystalline Si technology with the simpler and cheaper large area deposition technology of amorphous silicon.

However, conventional c-Si manufacturing technology has continued its steady improvement year by year and its production costs are still falling too.

The emerging thin film technologies are starting to make significant in-roads in to grid connect markets, particularly in Germany, but crystalline technologies still dominate the market. Thin films have long held a niche position in low power (<50W) and consumer electronics applications, and may offer particular design options for building integrated applications.