Cadmium – Greenhouse Gases

Posted on September 3, 2010 by

One issue that have always raised the concerns is the use of cadmium in cadmium telluride solar cells in manufacture of certain types of photovoltaic products. Cadmium in its metallic form is a toxic substance that has the affinity to build up in ecological food chains. The amount of cadmium used in thin-film photovoltaic products is relatively very small (5-10 g/m²) and with good emission control techniques in place the cadmium emissions from photovoltaic module production can also  be brought to almost zero. Current technologies lead to cadmium emissions of 0.3-0.9 mg/kWh over the whole life-cycle of the product. Most of all these emissions actually occur through the use of coal power for the manufacturing of these products, and coal combustion leads to much higher emissions of cadmium.

No emissions of any kind can be gproduced when using photovoltaics modules under normal conditions and during probable accidents (e.g. fires, breakage). New studies have proved that cadmium in glass–glass modules would not be released during fires because it dissolves into the molten glass and remains there. Any comparisons made with cadmium emissions from new coal-fired power plants are mistaken because they compare unlikely possible accidental emissions from PV systems to routine emissions from conventional power plants. In actuality, when photovoltaic plants replace coal burning for electricity generation, it will prevent cadmium emissions as well as large quantity of CO2, NOx, and small particulate emissions. By comparison with Ni–Cd batteries, a CdTe photovoltaic module uses cadmium about 2500 times more efficiently in producing electricity. A 1 KW photovoltaic system contains less cadmium than 10 size-C Ni–Cd batteries. In addition, CdTe is more firm and less soluble than the cadmium workings used in batteries.

But if electricity produced by photovoltaic panels were used to manufacture the products instead of electricity from burning coal, cadmium emissions from coal power procedure in the manufacturing process could be completely eliminated.

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Greenhouse Gases

Posted on August 27, 2010 by

Greenhouse gas emissions are now approximately in the range of 25-32 g/kWh and this could decrease to approx 15 g/kWh in the future. For comparison, a combined cycle gas-fired power plant emits some 400-599 g/kWh, a coal-fired power plant 915-994 g/kWh, an oil-fired power plant 893 g/kWh and a geothermal high-temp power plant 91-122 g/kWh. Only geothermal low- temp and wind are better,emitting 11 g/kWh and 0-1 g/kWh]. Including the energy required for mining uranium and the energy-intensity spent during power plant construction and decommissioning it, some place nuclear power plants’ life-cycle greenhouse gas emissions are below 40 g/kWh, but many others give much higher figures.

Using renewable energy sources in manufacturing and transportation would have an additional drop in carbon emissions. BP Solar owns two factories in US built by Solarex in which all of the energy used to manufacture solar panels is produced by only solar panels. But a 1-kilowatt system eliminates the burning of approx 170 pounds of coal, 300 pounds of carbon dioxide from being on the loose into the atmosphere, and saves up to 105 gallons of water use monthly.

The main life-cycle environmental harmful impacts of silicon photovoltaic panels come from the production phase and include:

The energy consumed during panel production and the emissions linked with that energy production;

Water consumption, which is cleaned and reused in the watershed;

Some hazardous end products which are released to the air or recycled and reused in additional production processes.

All air emissions are in retreat to pollution control equipment and covered under a Department of Environmental Quality (DEQ) air sanction. All wastewater is treated and monitored preceding to discharge under the water permit. The positive impact during the photovoltaic panel use or energy generation stage is the emissions-free energy that displaces carbon intensive energy production from sources such as coal and natural gas. The optimistic impacts of that displacement far outweigh the negative impacts of the production phase of the life cycle of silicon photovoltaic panels.

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Environmental Effects caused during the production of Photovoltaic products

Posted on August 21, 2010 by

Unlike traditional fossil fuel based technologies, solar power does not lead to any damaging emissions during operation, but the production of the photovoltaic products end result to some extent of pollution.

The ecological issue that are considered most linked for photovoltaic power systems were recognized in the workshop as well as the approach that may be used to examine them. The main environmental issues discussed at the induction were:

Energy utilized

Resource exhaustion. For example, the resource accessibility for indium (used in CIS-modules) and silver (used in mc-Si modules) has been indicated as potentially challenging.

Climate alters. Greenhouse gas emissions (notably CO2) mostly begin from energy use and the potential for photovoltaic power systems to decrease these emissions is receiving rising attention.

Health and Safety. Nonstop or accidental release of hazardous resources can pose a hazard towards workers and the public.

Waste produced.

Land use; at least in the case of ground-based setup.

A life cycle advance is needed for the evaluation of environmental aspects of photo voltaic power systems because they mostly happen at life cycle stages other than the process of that itself. This life cycle approach is included in the recently developed method of environmental Life Cycle Assessment (LCA). This involves the comprehensive assessment of all environmental impact throughout the life cycle of a product, service and sector of the economy or the society as a whole. Due to the high degree of difficulty of any comprehensive analysis structure, lack of consent regarding the assessment of various environmental impacts, and lack of information, simplified forms of LCA have been developed and applied to the assessment of photovoltaic power systems. Energy pay back times and CO2 alleviation potentials of these power systems are the results of basic forms of LCA and may be used to give a first indication of environmental aspects. Since these indicators do not express all photovoltaic specific environmental risks, Health, Safety and Environmental assessment and control is needed as a complementary process.

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Current Development

Posted on August 16, 2010 by

Photovoltaic panels based on traditional Crystalline silicon modules which are being partly replaced in the market by panels that utilize thin-film solar cells, which are fast growing and are likely to account for 31 percent of the globally installed power by 2013]. Other major developments include casting wafers as an alternative of sawing, silver cells technology, continuous printing and concentrator modules. Due to economy of scale of solar panels get less costly as consumer use or buy more, also as manufacturers amplify production to meet demand, the cost is expected to drop in the days to come.

In 2006 many investors in US began offering free solar panel installation in return for a 25 year contract, or commonly called as the Power Purchase Agreement, to purchase electricity at a fixed price, normally set at or below current running electric rates. It is expected that by 2009 over 90% of commercial photovoltaic products installed in the US will be delivered using a power purchase agreement. A novel financing pact is being tested in Berkeley, California, which adds an amount to the property evaluation to allow the city to pay for the installed solar panels up front, which the property owner pays over a 20 year period at a rate equal to the yearly electric bill savings, thus allowing free installation for the house owner at no cost to the city.

The current market leader in solar panel efficiency (measured by energy conversion ratio) is Sun Power. Its power cells have an alteration ratio of 24.2%, well above the market average of 12-18%. However, advances past this efficiency mark are being pursued in research at universities and labs with efficiencies of 42% achieved at the University of Delaware in combination with DuPont by means of concentration of light source. However, absorption efficiency should not be confused with the sunlight-to-electricity conversion efficiency.

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Disadvantages of Photovoltaic Products:

Posted on August 10, 2010 by

Photovoltaic products are costly to install. As the modules are often warranted for upwards of 20 years, generally much of the investment in a home-mounted system may be lost when the home-owner moves and the buyer puts less value on the system than the actual price.

Photo electricity also seen to be expensive. Once a photovoltaic system is installed it will produce electricity for no additional cost until the inverter needs replacement. At current situation utility rates have increased every year for the past 2 decades and with the increasing pressure by eco governing bodies on carbon reduction the rate of production will increase more aggressively. This increase will effect in the long run easily offset the elevated cost at installation but the timetable for payback of investment is too long for most cases.

Photo electricity is not available at night and the available is constricted on cloudy weather conditions .Therefore, a complementary power system is required. This is why many buildings with photovoltaic setup are tied into the power grid; this grid absorbs excess electricity that is generated throughout the day, and provides electricity in the evening or during unfavourable condition.

Distant from their own efficiency figures, Photovoltaic systems work within there restricted power density of their location’s insolation.

Solar cells produce direct current which must be converted to alternating current (using a transformer) when used in current existing grids. This incurs an energy loss of 4-12%.

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Advantages of Photovoltaic Products

Posted on August 2, 2010 by

The 89 peta watts of photo energy is reaching the Earth’s surface from the sun is plentiful, its almost 6,000 times more than the average electrical power consumed by humans. And moreover photo electric generation has the highest power density (global mean of 170 W/m²) among all other renewable energies.

Solar power is considered to be pollution-free during use. Production end-wastes and emissions are minor and can be manageable using existing pollution controls norms. End-of-use recycling technologies are also under development.

Photovoltaic installations can operate for long years with little or no maintenance or intervention cost after their initial set-up, so after the initial investment of building any, solar power plant and operational costs are extremely low compared to existing power technologies.

Photo-electricity generation is economically and far more superior where grid connection or fuel transports are impossible, difficult, or costly. Best examples include satellites, remote locations in Arctic and Antarctic region island communities and ocean vessels.

When solar electric generation replaces some or all of the grid-connected supply, highest-cost of electricity used during times of peak hours. This can reduce a lot of grid loading, and can eliminate the need for a local battery power used in times of darkness. These quality are enabled by net metering. Time-of-use net metering can be highly constructive, but needs newer electronic metering methods, which may still be not practical for some users.

Grid-connected photo electricity can be used in the vicinity thus reducing transmission or distribution losses.

Compared to fossil fuel and nuclear energy sources, very little research funds have been invested in the advance of photovoltaic solar cells, so there is considerable scope for improvement. Yet, experimental models of high efficiency solar cells which already have efficiencies of 40% in case of fixed photovoltaic cells and efficiencies are quickly rising and mass-production costs are rapidly falling.

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Space Satellites : Products

Posted on July 28, 2010 by

Spacecraft functioning in the inner solar system regularly rely on the use of photovoltaic solar grids to obtain electricity from sunlight. In the outer solar system, where the sunlight is too fragile to produce adequate power, radioisotope thermal generators are used as a power source.

Photovoltaic products are always by tradition been used for secondary power in outer space equipment .Design studies of large solar power cell set satellites in outer space have been conducted for past decades now. This ground-breaking idea was first proposed by Peter Glaser, and then of Arthur D. Little Inc; NASA, ISRO and other space agencies across the world has conducted a long series of engineering and economic viability studies in the early 1970s, and interest has been rejuvenated in the early 21st century.

From a realistic economic viewpoint, the key issue for such satellites seems to be in the launch cost. Additional considerations are also being given will in developing space based assembly procedures, but they seem to be less of a hurdle than the capital cost spent. These will be further reduced as photovoltaic cell costs are reduced or alternative and efficient ones are made.

These just the tip of enormous ice berg, as photovoltaic products have endless applications and new ones are found every single day.

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In Transport : Products

Posted on July 22, 2010 by

They are not often used to provide locomotive power in road transport applications, but are being used gradually more nowadays to provide support power in boats and cars. Recent advances in road cars however have produced cars that with very little changes could be used for transportation.

Photovoltaic modules are used commercially as secondary power units on passenger cars in order to direct ventilate the car, sinking the temperature of the passenger section while it is parked in the sun. Vehicles such as the Prius, Aptera, Audi A8, and Mazda have had solar sunroof options for aeration purposes.

The area of photovoltaic modules requisite to power a car with conventional design is too large to be carried aboard. A trial product car and trailer has been built Solar Taxi. According to the website, it is has an average of 100 km/day using 6 meter square of standard crystalline silicon cells. Electricity is stored using a nickel-salt battery. A fixed system such as a rooftop solar panel, however, can be used to charge conventional electric vehicle.

It is much more practicable to run an ultra light vehicle on solar energy than a regular car. Many prototypes have been made for competitions such as the World Solar Challenge. The solar challenge cars have an average 100 km/h for long distances. For 2007 a new Challenge class specified an erect seating position and smaller solar panels to create a class of vehicle which with little alteration could be the basis for a practical proposal for sustainable transport. The winning car still managed an average speed slightly in excess of 90 km/h (56 mph). The Venturi AstroLab in 2006 was declared as the world’s first commercial electro-solar hybrid car which is due to be released , with a solar range of 18 km/day and a total range of roughly 110 km it can be charged either from the sun or from the AC mains.

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In Buildings : Uses

Posted on July 18, 2010 by

Electricity for home or other buildings further than than a couple football fields from the nearby electrical lines, may be cheaper if obtained from photovoltaic cells than by buying electricity from the home power utility, because of the cost of running an electrical lines to the home. In most urban areas, however, buying electricity from a utility would cost less than using photovoltaics.

The outlay of using photovoltaic technology is not only based on the photovoltaic cells themselves but also on the batteries and tools needed to condition the electricity for house use. Modules made of group of photovoltaic cells set side-by-side and linked in series generate direct current (DC) at a relatively low voltage, but mainly household appliances use alternating current (AC). Inverters and power conditioners can convert DC to AC current at the correct voltage.

The type of appliances in the house is also a thought for whether to use photovoltaic. Some electrical devices—like televisions, air conditioners, blow-dryers—need a lot of power, sometimes all at once. Because of this photovoltaic cells do not change the amount of voltage they can provide; this sort of load can drain batteries quickly. Many of those with houses powered by photovoltaic cells buy energy-efficient lights and appliances and limit the number of needless electrical devices in their homes.

Photovoltaic setup is often linked with buildings, integrated into them, mounted on them or place nearby on the ground. Usually setup are most often retrofitted into existing or old buildings, usually they are mounted on top of the existing roof or on the walls. Alternatively, a setup can be situated separately from the building but connected by cable to supply power to the building.  BIPV or Building Installed Photovoltaic’s are increasingly included into new domestic and industrial buildings as an ancillary source of electrical power. Roof tiles with integrated photovoltaic cells are also becoming very common these days.

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WHAT IS PHOTOVOLTAIC PRODUCT?

Posted on July 16, 2010 by

Photovoltaic products are best known as a innovative method for generating electricity by using solar cells to convert energy derived from the sun. Photovoltaic products are arrays of cells consisting of a solar photovoltaic material that traps and converts solar radiation into DC type of electricity. Materials that are presently used in production of photovoltaics include polycrystalline, copper indium selenide, amorphous silicon monocrystalline silicon and polycrystalline silicon and cadmium telluride. Due to the growing demand for renewable energy sources, the manufacture of solar cells and photovoltaic arrays has advanced dramatically in recent years

These solar cells require protection from the environment and hence are usually sealed tightly behind a thin sheet of glass. When there is a need for more power is required than a single cell cannot deliver enough, hence we need a large collection of solar cells in a photovoltaic setup. Cells are electrically linked together to form photovoltaic setup called solar panels. A single module can generate enough to power for an emergency telephone, but for fulfilling a house or power plant requirements the modules must be considerably large and should be arranged in multiples as arrays or formations. These setup piles up to be a large investment and the selling price of modules is still too high to compete with grid electricity in most places across the world, significant financial incentives around the world , which has triggered a enormous growth in demand for photovoltaic product.

Photovoltaic fabrication has been growing by an average of more than 20 percent each year since 2000, making it the world’s fastest-growing power technology. At the ending of the year 2009, the cumulative global installations surpassed 21,000 megawatts. Germany alone installed a record 3,800 MW in 2009. In an average 90% of this energy generating capacity consists of grid-tied electrical projects.

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