How Solar Water Heating Can Generate Electricity

The use of solar cell collections in the production of electricity is now a recognizable application. Although the majority of applications using photovoltaic or PV modules are still quite small in scale, there are some experimental stations attempting to generate power at the same level as that of the utility companies.  Nonetheless, everything from lawn lights to complete power systems are available for our homes right now. 

There is, however, another way to generate electricity and it's a method that has been used for quite a while - heating water. 

For decades steam generation plants have been in use where water is heated by the burning of coal, natural gas or oil.  This heated water is then turned into steam and used to drive a turbine which, in turn, produces the circular motion for the generation of electricity. 

The great 19th century British scientist and inventor, Michael Faraday, uncovered that when a coil of wire is turned close to a magnet, the result is that electricity is produced and this is what is used in the many applications where a generator provides power.  The principal is the same in basic terms where turbines are concerned, except steam power is used to do the turning. 

The turbine works in the same way no matter how the water is heated in order for the blades to be turned and the electricity produced.  However, using solar heated water produces much less pollution than other methods even when the component manufacturing effects are taken into consideration. 

As far as ordinary solar water heating systems go collector panels are used to collect the water on top of the roof.  The greenhouse effect is used to heat the water and it is then passed down a path of pipes and channels and stored in a storage tank. 

There is, however, one problem.

The total amount of sunlight received in any one area at a time is fixed. Although it will vary by weather conditions such as how much dust is in the air and the cloud cover for example, it's not possible to be adjusted on an upward scale as the sun's output can't be controlled.  Nevertheless, by being able to adjust the way the energy is used it is possible to control the amount and way in which the usable energy is applied. 

This can be done by having more efficient collector systems in place.  An example of this is the parabolic mirror method. 

Shaped roughly like a segment of a sphere, a mirror can focus the rays of the sun to an approximate line or point.  The sharpness of the focus is determined by the shape and quality of the mirror being used.  A cylindrical parabola focuses to a line whereas a circular parabola, something similar in shape to satellite dish, focuses to a point. The energy is then concentrated to be received into a smaller area.  This allows the water temperature to be greater than the alternative methods even though the same amount of energy is used.  

The water temperature can be raised to as high as 428F (220C) by the solar heating collectors using parabolic troughs and other shapes.  With water boiling at 212F (100C) this extremely high temperature water makes steam in a contained vessel under very high pressure which is then the source of power for the electricity producing turbine.  

Due to the fact that both the temperature and pressure are high, the conversion efficiency of the apparatus is also high.  This is the result of a basic principle of the physics of heat and what makes it possible to develop the solar electricity generation appliances with an efficiency rate of 40% compared to that of photovoltaic panels which range from 10-15% in the efficiency.

It goes without saying that these systems may not be suitable for the homeowners in general.  On the other hand, as the cost of coal, natural gas and oil gets higher and the price of solar systems drops down, businesses have started to experiment as far as solar power is concerned.  Who knows?  The supply of electricity from large solar turbine based plants may well be an option and provide a significant percentage of the total energy needs of the average person one day in the not so distant future.