under the sun

 Difficulties of using solar

Solar energy is difficult to quantify.For example, (HSL) is an active solar method of using sunlight to provide illumination. Hybrid solar lighting systems collect sunlight using focusing mirrors that track the sun. The collected light is transmitted via optical fibers into a building’s interior to supplement conventional lighting. In single-story applications,the systems of Hybrid solar lighting (HSL) are only able to transmit 50 percent of the direct sunlight received.That means almost half of the solar energy is wasted.The other example is Daylight saving time (DST).It utilizes solar energy by matching available sunlight to the time of the day in which it is most useful. DST shifts electricity use from evening to morning hours thus lowering evening peak loads and the higher costs associated with peaking electricity. In California, winter season DST has been estimated to cut daily peak load by 3 percent and total electricity use by 3400 MWh. DST has been estimated to reduce early spring and late fall peak loads by 1.5 percent and total daily electricity use by 1000-2000 MWh. DST, like other solar energy technologies, has not proven successful in all regions.

It is difficult to gain enough energy from solar energy .In instantce,one method of using solar energy is water heating. Solar water heating technologies have high efficiencies relative to other solar technologies. Performance will depend upon the site of deployment, but flat-plate and evacuated-tube collectors can be expected to have efficiencies above 60 percent during normal operating conditions.However,solar water heating is only appropriate for low-temperature (25-70 °C) applications such as swimming pools, domestic hot water, and space heating. The most common types of solar water heaters are batch systems, flat plate collectors and evacuated tube collectors.If we want to gain hotter water we still need get help from fossil fuel.Though fossil fuel is one form of solar energy,it will be used up in 100years.

And for solar powered cars, as far as solar powered cars go , their slower speed might not appeal to everyone caught up in today’s rat race.

The third problem is the high initial cost of installing a solar energy system.The initial cost is the main disadvantage of installing a solar energy system, largely because of the high cost of the semi-conducting materials used in building one. The cost of solar energy is also high compared to non-renewable utility-supplied electricity. As energy shortages are becoming more common, solar energy is becoming more price-competitive.
And also solar panels require quite a large area for installation to achieve a good level of efficiency. Potentially large areas of land are required for large-scale solar energy projects. The efficiency of the system and the reliability of solar energy also rely on the location of the sun and the amount of sunlight in any particular area, although this problem can be overcome with the installation of certain components. The production of solar energy is influenced by the presence of clouds or pollution in the air. Similarly, no solar energy will be produced during evening although a battery backup system and/or net metering will solve this problem. But the problem is,not many places in the world have enough constant and intense sunshine to make commercial use of solar energy practical. So,if you live in a region where there is limited amounts of sunshine ,it may be difficult to maintain a constant supply of solar energy.

On the other hand, the demand for electricity throughout the world is tremendous, and until improved methods of producing and storing solar power are developed, it will be quite costly to produce adequate amounts of solar energy. Solar power requires a means to store the electricity that is produced. Storage of this electricity is an issue and a reliable back-up means of electricity is required at the present time. It is expensive to build solar power stations and a solar cells cost a lot in comparison to the amount of energy they will produce over their lifetime. Solar power does not work at night, thus the need for back-up methods of providing electricity.

 references:

http://www.ces.purdue.edu/extmedia/AE/AE-89.html

 http://www.gosolarcalifornia.ca.gov/solar101/history.html

yuan zhao