Learning About Dirt

Solar Power. Everyone is familiar with this as it is one of the most commonly mentioned alternative energy sources. Solar panels are popping up all over the US. Solar panels can be found anywhere from on top of private homes to the roofs of huge corporations. Towns such as Austin, Texas are already incorporating solar panels into their search for energy that is not derived from oil. A bold move for a state so married to the oil industry. If only La. would follow their lead. There is certainly enough sun here to allow solar energy to provide for a great deal of energy.

This is what I learned about solar energy and how it works:

Solar cells convert one form of energy (sunlight) into another form of energy (electricity). When the sunlight is reduced or stopped, for example, when a cloud passes in front of the sun or when the sun goes down in the evening, the conversion process slows down or stops completely. When the sunlight returns, the conversion process resumes. Solar cells do not store electricity. At night, a solar electric system needs some form of energy storage, usually batteries, to draw upon instead of the solar cells.

Most solar cells are made from silicon, the 14th element. Other materials are used as well, but the fundamental process of how those cells work is the same as for silicon cells. Silicon has properties of both a metal and an insulator. Atoms in a metal have loosely bound electrons that flow easily when a voltage, or electrical pressure, is applied. Atoms in an insulator have tightly bound electrons that cannot flow even when a strong electric voltage is applied.

Atoms in a semiconductor bind their electrons somewhat more tightly than metals, but more loosely than insulators. Their electrical conductivity can be varied by a factor of thousands by introducing small amounts of impurities, or “dopants,” into the semiconductor structure. The two elements typically used to dope silicon are phosphorous and boron.

At the atomic level, light is composed of energy particles called photons that flow from the sun and strike the solar cell. As each photon strikes a silicon atom, it ionizes the atom by transferring its energy to an outer electron, allowing it to break free of the atom. The energy of the photon is converted into electron movement energy called electric current.

Another reason to use silicon in solar cells is because the energy needed to ionize a silicon electron matches the typical energy of photons coming from our sun. If the photons had less energy (if our solar spectrum were more red or infrared), they would not have enough energy to free the electrons, and if the photons had more energy (if our solar spectrum were more blue or ultraviolet), the energy beyond that necessary to free the electron would be lost as heat and wasted.

Here is a diagram that sums it all up quite concisely:

This was a very interesting paragraph to read about Solar panels also:

• Passive solar house design is an excellent way to heat a home. Generally it’s designed into the home from the ground up, with south-facing windows, thermal mass to store heat, lots of insulation, and thermal blankets for the windows at night. DanF’s home was designed this way. Until we do get a page up here about passive solar heating, you can search the internet for the term and get a wide variety of books and articles on the topic.
• Solar hot water heating panels became very popular in the USA in the late 1970s and early 1980s for preheating a homes hot water. Government tax credits were offered by the Carter administration, and many companies sprang up designing and installing systems. When the Reagan administration cancelled the tax credits, many of these companies went out of business, and there were very few people left to maintain and repair these systems. Many of them are still sitting on roofs today, broken. HOWEVER, it became obvious very quickly that some of these companies were ‘fly-by-night’ and their products were poorly designed in the first place:
  • In general, we advise against purchasing these old systems used. It’s actually easy to find one for free, which might be OK if you are experimentor and enthusiast. But these older systems used numerous active controls, sensors and pumps, and were very unreliable compared to the excellent, low-maintainance and reliable systems available today.
  • Solar water heating panels are NOT a new idea! This article about the history of solar water heating is an excellent read. Thousands of systems were installed and were very effective in sunny parts of the USA around 1900.
  • On the other hand, modern solar water heating panels are an excellent investment in most parts of the county! The technology has changed so much that these systems are now completely different in design than those from the Carter area that caused so many problems. Some industry analysts say that the loss of the tax credits, while it had a large negative impact on the industry at the time, ended up being the best thing that ever happened to the industry in the long run.
  • These systems are now often incorporated along with radiant floor heating pipes. The sun heats the fluid, which circulates inside the high thermal mass floor of the home. This is a VERY efficient way to heat a home!
• Solar air heating panels are another new technology that’s catching on quickly. It allows the homeowner to retrofit a house that was not originally designed for efficient passive solar heating, and reap the benefits and energy savings of heating with the sun.

Below are a series of images of solar energy panels ranging from the large scale projects to personal homes:

Below is a common sight on the highways of the US as of late:

More and more we are seeing solar power being used by the government which is a good thing, especially with the cost of oil skyrocketing. If done properly, I believe we could power whatever idea/design we each have for the Perkins Underpass via renewable sources of energy.