Summary And Applications

In this experiment you were introduced to a modern marvel called a solar cell that produces electricity directly from sunlight. Solar cells, like the batteries you studied in Experiment 1, can be placed in series or parallel with the same voltage and current results. That is, solar cells in series add the voltages of all the cells while the total current remains at that produced by a single cell. Conversely, solar cells in parallel add the currents produced by all cells with the total voltage being equal to just a single cell. Naturally, you can combine all sorts of arrangements of series and parallel hookups to produce the voltage and current you want for your application.

These are just some ways solar cells mimic the way conventional batteries are used in day-to-day applications. However unlike even rechargeable (secondary) batteries, solar cells cannot store energy nor do they need recharging. They are either producing power from the sun, or not. This is why we started with a rechargeable battery experiment to let you understand that solar cells need a means to store the energy they collect.

On a more career-oriented note, by your choosing to perform this and the next experiment you may begin to understand the potential impact of solar cell technology on the production of electricity as we begin the 21st century. Recall that the Wright brothers first demonstrated heavier-than-air flight in 1903 -something that was deemed impossible prior to that time. In less than seventy years from that momentous flight, man successfully landed on the moon, which was also deemed an impossible task. Now here you are at the beginning of the 21st century with what appears as the ultimate in technology all around you, with nothing very significant to invent or improve upon. People felt the same way 100, 200 and more years ago, as well.

Solar cell technology has become just one example of this myopic view of the future. For years the "promise" of solar cells powering our homes and businesses never quite came true. We are still dependent on fossil fuels as our primary power source. Certain scientists and engineers still tell us that solar technology can never exceed certain technical and cost boundaries, so we are stuck with conventional fuels for the foreseeable future. Their predecessors also told the Wrights and Edison the same thing in their time about the airplane (it can never happen) and the electric light bulb (an inventor's pipe dream). However, just like the Wright brothers and Thomas Edison who both single-handedly pioneered their chosen fields of endeavor, all it takes is one or two enterprising individuals to bring solar cell technology into the "light" where it can become the dominant power source for clean renewable energy from the sun. Maybe one of those individuals is you. We certainly hope so!

Real World Examples

Solar energy can be captured and used in basically two forms - heat and electricity - the latter being called PV or photovoltaic energy. Solar energy in the form of heat is used to heat swimming pools as well as homes. For our experiments, the focus was and is on the photovoltaic energy produced by solar cells. For example, some rural homes are powered entirely from the sun and wind. With a combination of solar and wind, or just one or the other by itself, people can now live where ever they choose with all the conveniences of modern living like telephones, television with a satellite feed, the Internet and World Wide Web and even a toaster and electric range to cook with. Even 30 years ago this was an unthinkable circumstance. Now anyone with the correct installation of solar panels, inverters and batteries can live wherever they want with all the comforts of a grid-powered home.

But you don't have to live in the wilds to experience the impact of solar power on your day to day living. These days, solar cells are quite ubiquitous - you can find them powering everything from calculators, to portable radios, to hand-held games and even cell phones for battery recharging. Larger solar panels are used to power emergency telephones, which are placed along major highways. And very large solar panel arrays are erected on building roofs. Here they are used to generate AC voltages, using a device called an inverter that contributes to powering the building's lights, air conditioners and office equipment, thus saving power (and the cost of power) from the grid.

Real World Applications

So how can you find real world applications for solar cells other than the ones just mentioned? Well how about the family car's battery? It normally gets it charging from the alternator that, in turn, is powered by the car's engine by means of a fan belt. But

Figure 3-11

Automobile Dashboard Solar Panel

Photo by John Gavlik what if the car isn't driven for days or even weeks?

Figure 3-11

Automobile Dashboard Solar Panel

Photo by John Gavlik

In this case the battery will run down and not provide enough starting power for the car. The solution is a solar panel that sits on the dashboard, like the one owned by the author shown in Figure 3-11. It plugs into the cigarette lighter socket, these days also called a DC adapter socket. If the car is left out in the sun during the day, the solar panel will supply enough current to keep the car's battery "topped off' so that it is ready to start the car. You can find these kinds of solar panels at auto parts stores as well as electronics hobby stores. They sell anywhere from $19.95 to $49.95 depending on their particular voltage and current generating capabilities.

Another application for solar panels is on sailboats. Here the solar panels can be molded into the deck of the boat with clear resin, or hung on the railings like the one in Figure 312, or on a roof like in Figure 3-13. This way the panel keeps the boat's batteries constantly charged and also allows the crew to walk on the deck without destroying the panel.

Figure 3-12

Sailboat with Solar Panel Mounted on Rail

Photo by John Gavlik

Figure 3-12

Sailboat with Solar Panel Mounted on Rail

Photo by John Gavlik

Sailboats generally don't run their inboard engines very often, so keeping a battery charged is of primary importance when and if the engine needs to be started. Also, even modest sailboats like to have the convenience of light at night to read with and also to power the running lights, which are the red, green and white lights required by law to be on during nighttime cruising. Solar panels are quite useful in the marine environment since "getting a jump start" is something quite inconvenient, if not impossible, depending upon where your vessel is located at sea.

More Information

Here's where to find more information on solar cells:

www.learnonline.com/ewre.html.

Solar Panel Basics

Solar Panel Basics

Global warming is a huge problem which will significantly affect every country in the world. Many people all over the world are trying to do whatever they can to help combat the effects of global warming. One of the ways that people can fight global warming is to reduce their dependence on non-renewable energy sources like oil and petroleum based products.

Get My Free Ebook


Post a comment