| If you think about it, all energy is ultimately solar energy | | | | structure; silicon is the most common and least |
| - even fossil fuels. Coal and petroleum are the result of | | | | expensive, but others are also used. When the |
| rotting vegetable matter that was buried and subject | | | | semiconductor is "doped" - that is to say, combined |
| to intense geologic pressures hundreds of millions of | | | | with small amounts of insulating elements such as |
| years ago. | | | | boron and phosphorus - the conductivity of the |
| While alive, this plant matter captured sunlight and | | | | semiconductor can be changed and manipulated. |
| stored it through the biological process of | | | | When sunlight hits the surface of the semiconductor, it |
| photosynthesis. This energy remained stored in the | | | | actually produces electrical current. This current can |
| plants' cells after they died, and over the eons, was | | | | then be used directly or stored in batteries. |
| converted to what we know as fossil fuels. (It's what | | | | The Problem |
| author and radio host Thom Hartmann calls "Ancient | | | | Of course, everything today boils down to money. Until |
| Sunlight.") | | | | recently, solar cells have been extremely expensive to |
| When you eat your vegetables, this stored solar | | | | produce. The main reason is that the process of |
| energy is converted into sugar by your digestive | | | | creating semiconductors requires the use of expensive |
| system - and allows your body to function. | | | | equipment and a whole lot of energy. By the time all is |
| These are examples of the indirect use of solar | | | | said and done, photovoltaic solar power still costs five |
| energy. Photovoltaic solar energy is the science of | | | | to seven times what the local power company |
| using the sun's power directly with the use of | | | | charges. |
| semiconductors. | | | | Another reason is that photovoltaic solar energy |
| What Are Semiconductors? | | | | panels have not been particularly efficient; in the past, |
| Since semiconductors are the key to producing | | | | only about 8% of the light that hits the surface was |
| photovoltaic solar energy, it's important to understand | | | | turned into usable electricity. |
| how these operate. | | | | Solutions |
| In electronics, there are conductors, usually metals such | | | | When it comes to efficiency, one of the solutions has |
| as copper and aluminum, through which electrons can | | | | been to create multi-layered solar panels in which each |
| move freely and which contain movable electric | | | | layer is "tuned" to a different part of the light spectrum. |
| charges. This is why electrical wire is usually made of | | | | In essence, this allows the panel to capture more |
| such metals. There are also insulators, which prevent | | | | sunlight. Currently, efficiency rates are around 40% - a |
| the flow of electricity; the best known is rubber. | | | | 500% increase from earlier panels. |
| Semiconductors fall somewhere in between. | | | | Nanotechnology also promises to greatly lower the |
| These have long been used in transistors and in fact | | | | cost of manufacturing solar panels - which will |
| are at the heart of most of the electronic devices we | | | | ultimately make photovoltaic solar energy competitive |
| take for granted today, including cell phones and | | | | with power generated by fossil fuels. |
| computers. The ideal semiconductor is crystalline in | | | | |