To appreciate a technology you sometimes need to warm up to it. So if you know how solar power works, you are better positioned to accept it as a potential solution for your home power needs. In the past decade, the photovoltaic cells have become one of the most popular products in the market. One of the big reasons for that is the boost the government has given the technology through incentives. These cells are not cheap and with many manufacturers in the market you need to become knowledgeable about these products. You need to be smart enough to pick the right products and solutions.
To understand how solar power works we need to know some basics. Our sun is basically a nuclear reactor that is generating loads of energy every second. All this happens due to nuclear reactions within the sun that releases energy in the form of photons or light. Each photon is a wave moving through the space and like any wave it has two basic characteristics: wavelength and frequency. The wavelength is the distance between two points on the wave in the same phase which the frequency is the rate at which a particle reaches the same phase in the motion of the wave. Evidently, wavelength and frequency are inversely related to each other.
Why are we talking about wavelengths to understand how solar power works? Well because the wavelength at which the solar equipment works is vital to judge how effective it would be. The sun’s light consists of many color frequencies. We can see some and we can’t see the others. Incidentally, the sun’s radiation contain more infra-red radiation than the visible light ones. So solar equipment that works under infra-red light absorbs more energy. Another concept is the light absorption. Anything that seems to have a color actually absorbs light from all other color wavelengths except its color – which it reflects back and hence we see it. Anything that looks black absorbs all the light, hence black solar equipment works better than colored ones.
The total energy radiated by the sun can satisfy our growing energy demands many times over. In fact, if we can generate 6 kWh of power from 5 square meters of PV cells, that energy is sufficient to power our whole house with all the appliances for that day. Just imagine the sheer quantity of energy we have been neglecting for centuries. Tapping the solar energy is basically, facilitating a photonic reaction between the sunlight and the PV to convert the light energy into electric energy that can be used to power our home. Of course, if you do not have the optimum solar energy absorption you will end up with an inefficient system.
There are some materials that are transparent enough to pass radiation through them but at the same time are good insulators not allowing the heat to escape. These are very important in building solar power equipment. A good choice for such functions is regular glass with iron silicon impregnations. This can pass a wide range of light wavelengths and also block the heat. Here it is useful to understand the concept of a filter. A filter in light terminology is a device that allows certain wavelengths to pass, but reflects the others.
A very good example of filter is our sunglasses. We get sunglasses that reflect UV rays and pass visible light. Similarly coatings on windows to block bright light are another example. Filters play an important role in glazing for solar water heaters. The aim is to maximize the energy collection from the sun’s rays which happens to be in the infra-red range the filters used for glazing are designed to pass these wavelengths and filter the less productive colors.
These three characteristics of materials: filtering, absorbing and reflecting will helps us know how solar power works. Even the windows made from glass that are supposed to pass white light do not do so completely; they actually pass just 85% of the light and rest is lost or filtered. Another common filter is our atmosphere. During dawn and dusk the sun’s rays travel further in the atmosphere and hence they are not that strong or bright. At noon, with sun directly overhead, the light travels perpendicular to the atmosphere so it traverses shorter distances this means it gets filtered less and hence is more powerful.
The same idea holds true for summers and winters as well. During summer more of the sun’s light reaches the earth surface as compared to winters. As a result, more sunlight is reflected and absorbed in summer. Absorption of photons releases energy in the form of heat and this heat warms the air. This why summers are hotter and winters are cooler. In fact, heat is nothing but a function of motion. When a surface absorbs energy its molecules start to vibrate and this generates heat. Thus when solar energy strikes the surface it causes the molecules to vibrate releasing heat energy. These are some of the basic aspects of solar energy that you must be aware of. Understanding these concepts will aid you in understanding how solar power works.
