Shrinking the cost for solar power

One of the big problems with solar power has been that it costs more than electricity generated by conventional means. But some experts think that, under certain circumstances, the premium for solar power can be erased, without subsidies or dramatic technical breakthroughs.

A sufficiently large solar thermal power plant (also called concentrated solar power, or CSP) could potentially generate electricity at about the same cost as electricity from a conventional gas-burning power plant, experts say.

It's not easy. The plant would also have to come with a large energy storage system, be built next to others and be located close to users. To date, no one has completed a facility that comports to all of these parameters, said Fred Morse, an energy analyst who has studied the issue.

"Solar thermal is available at much more attractive prices than solar photovoltaic. The land mass isn't huge, but it does take a while to build these," said Stephan Dolezalek, a managing partner and co-head of the clean tech practice at venture firm Vantage Point Venture Partners, an investor in Bright Source Energy, which builds solar thermal plants and components.

Both Dolezalek and Jiang Lin, who heads up the China Energy Group at the Lawrence Berkeley National Laboratory, said that solar thermal is likely the most promising technology in the entire alternative-energy field right now.

When asked when solar thermal can hit parity, Lin responded "now."

Thermal by the numbers
Conventionally generated electricity ranges between 5 and 18 cents per kilowatt hour (the amount of money to get a kilowatt of power for an hour) but in most places it's below 10 cents, according to the Energy Information Agency. Solar thermal costs around 15 to 17 cents a kilowatt hour, according to statistics from Schott, a German company that makes solar thermal equipment.

A solar thermal plant would need a facility to store the heat harvested in the day by its sunlight-concentrating mirrors so that the heat could be used to generate electricity at night. "You need the kind of system that can run in the evening," Morse said. At some sites, such as Nevada Solar One, excess heat is stored in molten salt and released at night to run the turbine.

The plant, ideally, should be capable of generating about 300 megawatts of electricity. Those plants can churn out electricity at about 13 cents a kilowatt.

That's still a relatively high price, so utilities would need to group two, three or more 300-megawatt plants together to share operational resources, Morse said. "They could share control rooms or spare parts," he said. That would knock the price closer to 11 cents a kilowatt hour.

"Under 10 cents is sort of the magic line," he said.

Dolezalek puts it another way: the plants need to be around 500 megawatts in size. Most solar thermal plants right now aren't that big. The 22-year-old thermal plant in California's Mojave Desert is 354 megawatts. Utility company Southern California Edison is erecting a 500-megawatt plant scheduled to open in 2009.

By 2014, solar thermal plants located in the Southwest could crank out nearly 3 gigawatts of power, estimated Travis Bradford of the Prometheus Institute for Sustainable Development, a nonprofit based in Cambridge, Mass. That's enough for about 1 million homes.

Costs can then be reduced further by building the plants close to consumers. It costs about $1.5 million per mile for transmission lines, according to statistics from Acciona Solar Power, which owns solar thermal plants. Solar thermal plants work best in arid deserts that get little rainfall. Since some of the fastest-growing cities in the world are located in sun belts, that's less of a problem than it used to be.

But getting to that point isn't easy. Land-use hearings and permits can drag on for years while construction costs rise. The amount of land required can be an issue too: the 354-megawatt plant in California occupies 1,000 acres. Larger plants would need more land, while smaller plants result in higher costs per kilowatt hour.

Even if all of these factors could be completely optimized, solar thermal power plants would likely not produce electricity at a level that would compete with coal plants. Coal plants, however, will likely be hit with carbon taxes in the near future, which will make solar thermal more competitive. Still, at less than 10 cents a kilowatt, solar thermal would be competitive with electricity from gas-powered plants.

Utilities will also likely work hard to lower the costs of solar thermal in the coming decades, Morse added. Utilities are under mandates to increase their renewable energy sources. Citizen groups often complain about wind turbines and the wind doesn't blow at a constant, predictable rate. Several companies are intent on tapping heat from under the surface of the earth to generate power. Geothermal power, however, works best only in certain locations.

"There is an enough flat, unproductive land in the U.S. to power the U.S.," Morse said. "We just don't have the wires to get there. Eisenhower built the national highway system. Some president will build the national grid."

SOLAR ELECTRICITY EXPLAINED

Solar electricity is created by using Photovoltaic (PV) technologyby converting solar energy into solar electricity from sunlight. Photovoltaic systems use sunlight to power ordinary electrical equipment, for example, household appliances, computers and lighting. The photovoltaic (PV) process converts free solar energy - the most abundant energy source on the planet - directly into solar power. Note that this is not the familiar "passive" or Solar electricity thermal technology used for space heating and hot water production.

A PV cell consists of two or more thin layers of semi-conducting material, most commonly silicon. When the silicon is exposed to light, electrical charges are generated and this can be conducted away by metal contacts as direct current (DC). The electrical output from a single cell is small, so multiple cells are connected together and encapsulated (usually behind glass) to form a module (sometimes referred to as a "panel"). The PV module is the principle building block of a PV system and any number of modules can be connected together to give the desired electrical output.

PV equipment has no moving parts and as a result requires minimal maintenance. It generates solar electricity without producing emissions of greenhouse or any other gases, and its operation is virtually silent.

What is PV power used for?

PV systems supply solar electricity to many applications in the UK, ranging from systems supplying power to city buildings (which are also connected to the normal local solar power network) to systems supplying power to garden lights or to remote telecom relay stations.

The main area of interest in the UK today is grid connect PV systems. These systems are connected to the local solar electricity network. This means that during the day, the solar electricity generated by the PV system can either be used immediately (which is normal for systems installed on offices and other commercial buildings), or can be sold to one of the electricity supply companies (which is more common for domestic systems where the occupier may be out during the day). In the evening, when the electrical system is unable to provide the electricity required, power can be bought back from the network. In effect, the grid is acting as a Solar electricity energy storage system, which means the PV system does not need to include battery storage.

Grid connect PV systems are often integrated into buildings. PV technology is ideally suited to use on buildings, providing pollution and noise-free solar power without using extra space. The use of photovoltaics on buildings has grown substantially in the UK over the last few years, with many impressive examples already in operation.

PV systems can be incorporated into buildings in various ways. Sloping rooftops are an ideal site, where modules can simply be mounted using frames. Photovoltaic systems can also be incorporated into the actual building fabric, for example PV roof tiles are now available which can be fitted as would standard tiles. In addition, PV can also be incorporated as building facades, canopies and sky lights amongst many other applications.

Stand-alone photovoltaic systems have been used for many years in the UK to supply solar electricity to applications where grid solar power supplies are unavailable or difficult to connect to. Examples include monitoring stations, radio repeater stations, telephone kiosks and street lighting. There is also a substantial market for PV technology in the leisure industry, with battery chargers for boats and caravans, as well as for powering garden equipment such as solar electricity fountains. These systems normally use batteries to store the solar power, if larger amounts are required they can be combined with another source of power - a biomass generator, a wind turbine or diesel generator to form a hybrid power supply system.

PV technology is also widely used in the developing world. The technology is particularly suited here, where electricity grids are unreliable or non-existent, with remote locations often making PV power supply the most economic option. In addition, many developing countries have high solar radiation levels year round.

Electricity from: Solar Energy

The ultimate source of much of the world's energy is the sun, which provides the earth with light, heat and radiation. While many technologies derive fuel from one form of solar energy or another, there are also technologies that directly transform the sun's energy into electricity.

The sun bathes the earth in a steady, enormous flow of radiant energy that far exceeds what the world requires for electricity fuel.

Since generating electricity directly from sunlight does not deplete any of the earth's natural resources and supplies the earth with energy continuously, solar energy is a renewable source of electricity generation. Solar energy is our earth's primary source of renewable energy.

There are two different approaches to generate electricity from the sun: photovoltaic (PV) and solar-thermal technologies.

* Initially developed for the space program over 30 years ago, PV, like a fuel cell, relies upon chemical reactions to generate electricity. PV cells are small, square shaped semiconductors manufactured in thin film layers from silicon and other conductive materials. When sunlight strikes the PV cell, chemical reactions release electrons, generating electric current. The small current from individual PV cells, which are installed in modules, can power individual homes and businesses or can be plugged into the bulk electricity grid.

* Solar-thermal technologies are, more or less, a traditional electricity generating technology. They use the sun's heat to create steam to drive an electric generator. Parabolic trough systems, like those operating in southern California, use reflectors to concentrate sunlight to heat oil which in turn creates steam to drive a standard turbine.

Two other solar-thermal technologies are nearing commercial status. Parabolic dish systems concentrate sunlight to heat gaseous hydrogen or helium or liquid sodium to create pressurized gas or steam to drive a turbine to generate electricity. Central receiver systems feature mirrors that reflect sunlight on to a large tower filled with fluid that when heated creates steam to drive a turbine.


What are the environmental impacts?

PV systems operate without producing air, water or solid wastes.

When constructed as grid-connected central station systems, they require significant land, which can impact existing ecosystems. Nevertheless, most PV installations come in the form of distributed systems that use little or no land since the panels are installed on buildings.

Manufacturing PV cells involves the generation of some hazardous materials. Nonetheless, appropriate handling of these small quantities of hazardous material reduces risks of exposure to humans and to the environment.

Like PV, solar-thermal technologies generate zero air emissions, though some emissions are created during the manufacture of both technologies. Water use for solar thermal plants is similar to amounts needed for a comparably sized coal or nuclear plants.

The biggest concern with solar technologies may be land use...

...since five acres of land are often needed for each megawatt of capacity. PV can eliminate the land use impacts by integrating the generators into building construction, eliminating the need for dedicating land use to PV generation.

How Do You Produce Electricity From Solar Energy

he answer to the question of how do you produce electricity from solar energy is fairly easy to understand once you have a slight knowledge of the subject.
Before you are able to produce electricity through solar energy, there needs to be some form of solar cell or panel.
The solar panels are made of a semi-conductive material, the most common material is silicon.
The semi-conductive material contains electrons which are quite happy just sitting there.
When photons (contained within the suns rays) hit the solar cells, the electrons absorb this solar energy, transforming them into conduction electrons.
If the energy of these photons is great enough, then the electrons are able to become free, and carry an electric charge through a circuit to the destination.
Any electrons that do not receive enough energy simply warm up, which heats your cell or panel, resulting in lowering the efficiency of the cell.
The lowering in efficiency is down to two main factors and they are; that the cell is not working to its full potential (e.g. some electrons may be lost), the second factor is when the electrons release heat, the panel also becomes warm, interfering with other aspects of the solar cells.
The more solar cells contained in a solar panel, or solar array, means the more output you will receive.
Quality cells are also a major factor in efficiency. If you purchase more expensive natural energy technologies, you are more likely to have a more efficient cell.
Another factor which affects solar panel efficiency is location. Obviously nearer the equator, you will receive a slightly better output with a given cell, but solar cells should always be facing the direction of the sun, and have no objects blocking the suns rays.
So there we have a basic understand of how you produce solar electricity from using energy within the suns rays.

Power Shortage

Expressing concern over load shedding in the twin cities, President Islamabad Chamber of Commerce and Industry (ICCI) Nasir Khan has said that solar energy is one of the solutions of power shortage, as sun is abundantly available without any cost. Addressing to the business community, he said that prolonged load shedding is affecting the business activities of industrialist and small traders badly. He regretted that during the moon soon rains IESCO still could not overcome problems of load shedding in the federal capital. He said the continuous power shortage is creating hurdles in the current pace of economic growth of the country. The growing gap between demand and supply of power and interrupted supply of power to industrial sector is retarding the country exports, he added.
While giving a presentation on importance of solar and wind energy, Nasir Khan, Erector of Solar and Winter Wind Plants said that solar energy is one of the solutions of power shortage, as sun is abundantly available without any cost. Solar energy systems can also work in overcast situations, he stated. But solar energy products, he said is out of reach of most of the population’s purchasing power. To solve this problem, a number of companies have manufactured low cost and affordable solar energy products.
He said that Pakistan lies in the region of trade winds, which give it a competitive edge to utilize this priceless resource to overcome the problem of energy shortage. In this respect Mr. Nasir Khan identified a few areas of Karachi and Gwader near Hawkes Bay and National Highway for installing both solar and wind energy plants to produce electricity.-SANA

Solar Investment

A “typical home” in America can use either electricity or gas to provide heat — heat for the house, the hot water, the clothes dryer and the stove/oven. If you were to power a house with solar electricity, you would certainly use gas appliances because solar electricity is so expensive. This means that what you would be powering with solar electricity are things like the refrigerator, the lights, the computer, the TV, stereo equipment, motors in things like furnace fans and the washer, etc. Let’s say that all of those things average out to 600 watts on average. Over the course of 24 hours, you need 600 watts * 24 hours = 14,400 watt-hours per day.

From our calculations and assumptions above, we know that a solar panel can generate 70 milliwatts per square inch * 5 hours = 350 milliwatt hours per day. Therefore you need about 41,000 square inches of solar panel for the house. That’s a solar panel that measures about 285 square feet (about 26 square meters). That would cost around $16,000 right now. Then, because the sun only shines part of the time, you would need to purchase a battery bank, an inverter, etc., and that often doubles the cost of the installation.

If you want to have a small room air conditioner in your bedroom, double everything.

I’ve been monitoring the usage of my house, and we consume about 10 Kilowatts per day (STEEP!!!). Now, in order to have solar panels for that, i would need a number of panels, from this site, i picked one at random, which produces 170 watts for an investment of $839 per panel. A quick calculation (from the data provided on the site), tells me i need atleast 6 of these panels to power my house meaning an investment of $5034 (or Rs. 3,02,040) without addding any sort of tax or extra charges on the modules and i need a space of about 30×15 feet to house it. (again from data provided for this module).

Now the KESC rate for domestic supply is about 7.5 per kilowatt (at their lowest slab), meaning that my monthly electricity bill becomes 2250 (without the charges, surcharges, and extra surcharges :S).

So, just on these ideal figures (just the power usage, no infrastructure costs), it would take me about 135 months or about 11 years just to breakeven the cost of the cells.

I think we should wait another decade or something, or encourage NEDians and other engineering universities to come up with solutions.. and let the prices fall down a bit. Its expected that the price will fall down to about 1/5 of what it costs now over the next decade.. which just may make this a viable option.

Solar energy

Solar energy is the most readily available source of energy. It does not belong to anybody and is, therefore, free. It is also the most important of the non-conventional sources of energy because it is non-polluting and, therefore, helps in lessening the greenhouse effect.

Solar energy has been used since prehistoric times, but in a most primitive manner. Before 1970, some research and development was carried out in a few countries to exploit solar energy more efficiently, but most of this work remained mainly academic. After the dramatic rise in oil prices in the 1970s, several countries began to formulate extensive research and development programmes to exploit solar energy.

When we hang out our clothes to dry in the sun, we use the energy of the sun. In the same way, solar panels absorb the energy of the sun to provide heat for cooking and for heating water. Such systems are available in the market and are being used in homes and factories.

In the next few years it is expected that millions of households in the world will be using solar energy as the trends in USA and Japan show. In India too, the Indian Renewable Energy Development Agency and the Ministry of Non-Conventional Energy Sources are formulating a programme to have solar energy in more than a million households in the next few years. However, the people’s initiative is essential if the programme is to be successful.

India is one of the few countries with long days and plenty of sunshine, especially in the Thar desert region. This zone, having abundant solar energy available, is suitable for harnessing solar energy for a number of applications. In areas with similar intensity of solar radiation, solar energy could be easily harnessed. Solar thermal energy is being used in India for heating water for both industrial and domestic purposes. A 140 MW integrated solar power plant is to be set up in Jodhpur but the initial expense incurred is still very high.

Solar energy can also be used to meet our electricity requirements. Through Solar Photovoltaic (SPV) cells, solar radiation gets converted into DC electricity directly. This electricity can either be used as it is or can be stored in the battery. This stored electrical energy then can be used at night. SPV can be used for a number of applications such as:
a. domestic lighting
b. street lighting
c. village electrification
d. water pumping
e. desalination of salty water
f. powering of remote telecommunication repeater stations and
g. railway signals.