A SEO Diagnosis For Webmasters

An addon called "SEO Doctor" for Firefox will be able to quickly diagnose your site for problems and also check your competitor sites. This addon allows you to see how any website you visit is optimized in terms of SEO.

It is made with both beginners and experienced SEO as the wealth of information is available as soon as you visit the website. It offers easy diagnosis of SEO problems and even offers solutions for common problems.

Once installed, SEO Doctor will become a part of your status bar and assign an SEO score to every page you visit. It also provides one-click access to some of the best free SEO tools available on the Internet today.

At glance :

* Shows link structure and page rank flow for your pages
* Detects search engine non-indexable pages using comprehensive methods
* Points out to potential problems and assigns a score based on common SEO methodology
* Quick access to most popular SEO tools
* Fully customizable

A SEO tool will never tell a person how to do good SEO, but will provide them with key data from different aspects, that can help formulate the right strategy for the site at that time. The tools will also save a fair bit of man hours doing the automated checking of the information. Obviously the search engines are constantly evolving and what works now may not work in the future so there needs to be a fair bit of monitoring to be done on the data collected.

Source : click here

Photovoltaics

Solar cells, also called photovoltaics (PV) by solar cell scientists, convert sunlight directly into electricity. Solar cells are often used to power calculators and watches. They are made of semiconducting materials similar to those used in computer chips. When sunlight is absorbed by these materials, the solar energy knocks electrons loose from their atoms, allowing the electrons to flow through the material to produce electricity. This process of converting light (photons) to electricity (voltage) is called the photovoltaic (PV) effect.

Solar cells are typically combined into modules that hold about 40 cells; about 10 of these modules are mounted in PV arrays that can measure up to several meters on a side. These flat-plate PV arrays can be mounted at a fixed angle facing south, or they can be mounted on a tracking device that follows the sun, allowing them to capture the most sunlight over the course of a day. About 10 to 20 PV arrays can provide enough power for a household; for large electric utility or industrial applications, hundreds of arrays can be interconnected to form a single, large PV system.

Thin film solar cells use layers of semiconductor materials only a few micrometers thick. Thin film technology has made it possible for solar cells to now double as rooftop shingles, roof tiles, building facades, or the glazing for skylights or atria. The solar cell version of items such as shingles offer the same protection and durability as ordinary asphalt shingles.

Some solar cells are designed to operate with concentrated sunlight. These cells are built into concentrating collectors that use a lens to focus the sunlight onto the cells. This approach has both advantages and disadvantages compared with flat-plate PV arrays. The main idea is to use very little of the expensive semiconducting PV material while collecting as much sunlight as possible. But because the lenses must be pointed at the sun, the use of concentrating collectors is limited to the sunniest parts of the country. Some concentrating collectors are designed to be mounted on simple tracking devices, but most require sophisticated tracking devices, which further limit their use to electric utilities, industries, and large buildings.

The performance of a solar cell is measured in terms of its efficiency at turning sunlight into electricity. Only sunlight of certain energies will work efficiently to create electricity, and much of it is reflected or absorbed by the material that make up the cell. Because of this, a typical commercial solar cell has an efficiency of 15%—about one-sixth of the sunlight striking the cell generates electricity. Low efficiencies mean that larger arrays are needed, and that means higher cost. Improving solar cell efficiencies while holding down the cost per cell is an important goal of the PV industry, NREL researchers, and other U.S. Department of Energy (DOE) laboratories, and they have made significant progress. The first solar cells, built in the 1950s, had efficiencies of less than 4%.

Find out about NREL research in photovoltaic technologies from DOE's National Center for Photovoltaics.

Also see DOE's Solar Energy Technologies Program.