Tina Metcalf asked:


The ultimate solar home has to be the International Space Station: three hundred and seventy five square meters of solar cell goodness, providing thirty kilowatts of sweet solar energy to run one of the most amazing feats ever assembled by man.  Of course it’s not all cheery, in space maintenance is a bit tricky, and the commute to work takes ages.

One person who knows of both trials is astronaut Heidemarie Stefanyshyn-Piper, who had an unusual accident while working to repair the station’s right solar wing.  The solar wings have motors which move them to point at the sun, ensuring maximum energy absorption.  Or rather they usually do, one joint on the wing jammed, locking the panels in place and cutting down on the power production.

While fixing the problem, Heidemarie was distracted by an exploding grease-gun and put her tool bag down for a moment.  Except, of course, in space there is no real “down” and the untethered tool bag promptly floated off into the great black yonder.  There are a few reasons this isn’t a serious problem for Earth-bound panels:

1)  Earth panels don’t usually move to track the sun – except in special systems, the energy cost of moving the panels against gravity is more than you’d gain.

2)  Tool bags on Earth don’t usually float off into space.  If you’ve got a tool bag that can do that, please contact a scientist immediately.

3)  Regular tool bags don’t cost a hundred thousand dollars.

Yes, the escaped equipment cost a whopping hundred grand, the bag being full of customized NASA-grade goodies.  Don’t be expecting a free astronaut baggie to be dropping in from above though,  the small package will burn up harmlessly on re-entry.  The mission continued with no other problems, and the astronauts now await tests which will tell them if they’re back to full power.



Paula

Anna asked:


A solar cell is a device which changes sunlight into electricity. A more technical term for a solar cell is a photovoltaic cell.

The term “photo” derives from the Greek word for “light,” and the term “voltaic” comes from the word “volt” which means “electrical force.” A “cell” is a small receptacle or container containing electrodes which generate power.

Thus, a photovoltaic cell is a container that creates electric force, through light.

Whereas a solar cell can generate electricity from any light source, its intended use is the collection of solar energy from the sun.

How a Solar Cell Works

The solar cell works as follows:

Photons (which are particles of light in sun rays) hit the surface of the solar cell and are absorbed a semiconductor, such as silicon.

These photons (bits of sunlight) knock electrons loose from the atoms inside the semiconductor. The photons then push the electrons along, leaving a “gap” in the atom. Another electron is then pulled from an adjacent atom to fill the gap. And so an electrical flow is generated.

The simplicity of this is that one atom has an extra electron, and the other atom is missing one. This is referred to as a “difference in potential.” Nature, wanting to remain balanced, tries to even things out by pulling another electron from the neighboring atom.

A solar panel is comprised of a group of solar cells which are linked together to produce the desired amount of electrical energy.

A group of solar cells linked together can also be referred to as a “module.” Thus the terms “solar panel,” and “solar module,” are synonymous to each other, and essentially mean the exact same thing. “Solar panel” is the more common term, and “solar module” is the technical term.

One can use solar panels individually or one can link several together in order to generate more electricity. When a group of solar panels are linked together, it is called a “solar array”. The more solar panels are included in a solar array, the more power they produce.

Solar Power is a clean and virtually unlimited source of energy. I say “virtually unlimited” because the sun itself won’t last forever. But we won’t have to worry about that for the next few billion years.

Since solar power is a clean energy source which has been around for decades, one might wonder why its not used more. The answer to this lies partially in the cost of producing solar panels, as well as in the efficiency of the solar panels.

We are currently in the second generation of solar panel technology and verging on the third. A lot has changed since the first generation. Solar panels a are becoming a viable source of clean energy.

The solar cells of earlier times were relatively large and bulky compared to our current models. In view of the amount of energy and material required to produce them, and the amount of energy they actually produced, it was more costly to use solar energy than to use fossil fuels. The only exception was in places where little or no fossil fuels were available, such as in space.

With the second-generation solar cells, we attempted to tackle this exact problem. We attempted improve manufacturing techniques so as to reduce the costs, materials and energy needed for the production of solar cells.

Recently, major advances have been made in the production of solar cells, which have reduced production costs.

One contribution in this area was the development of techniques to coat glass or ceramic materials with very thin layers of semi-conductive substances. This made it possible to produce solar panels using only a fraction of the semi-conductive material that was required earlier. The production of solar panels using this second-generation technology is referred to as “Thin Film Technology.”

Third-generation solar energy technologies are currently being researched and developed. The objective is to improve the power of solar cells even further (while keeping production costs to a minimum) in which case thirty to sixty percent of the sunlight hitting the panels will be converted into electricity. (Currently, solar panels convert only about twenty percent.)

But regardless of third generation solar technology, the second-generation solar cell is efficient enough to make solar technology viable – and a host of new solar-powered products have hit the consumer market.

Solar-powered calculators have been in use for a while now, we’ve all seen them. We have even seen a few other novelty devices. But only in the last few years have solar devices come into serious and practical use.

The last two years in particular have seen a virtual explosion of solar devices hitting the market. Solar flashlights (I’ve often wandered what use they were), solar-powered radios, and, recently, solar battery chargers.

One can also now find a wide range of portable solar chargers and panels, which are lightweight and easy to transport, yet capable of providing a decent amount of power in even the most remote locations. Solar chargers are becoming a standard part of wilderness survival kits and emergency preparedness kits.

All of this is a result of the developments in solar cell technology, and the coming of the Solar Age.



Aaron