Quote:
Originally Posted by scuba steve
stupid question but what happens when its overcast and cloudy for a few days? does it store energy?
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Actually it is fairly easy and inexpensive to construct a decent sized hot water storage facility for residential use. The hot water can be used for heating in winter and provide for those days during which the Sun is not realy shining. A parabolic reflector of sufficent size will even work on overcast days but not at anything like maximum efficiency of course.
The biggest problem with solar electricity is the fact that DC (Direct Current) is produced and this DC must be stored in large cumbersome and envrionmentally nasty battery banks which are composed of lead/acid, nickel hydride, lithium or other kinds of batteries. The DC must then be run through expensive inverters which convert the DC of the selected storage voltage to 120/240 volt 60 Hz AC (Alternating Current) in order for it to operate our electrical devices and appliances.
The doped solar cells require the use of arsenic and other highly toxic chemicals to be manufactured and therefore have their own environmental downside, so it remains to be seen whether or not this technology will have any real application.
One of the best ways to use solar in gneration of electricity is through solar powered steam generators, the steam from which is used to spin turbines connected to generators or to run large-scale Stirling engines which power the generators.
The thing to be remembered about solar power is that it only works when the Sun is shining and is subject to efficieny reductions due to ambient weather conditions and that there are only som many BTUs that hit the ground in a given area per day and you can't change that factor. You cannot suck down sunlight. Parabolic collectors do concentrate that energy though, allowing the equivalent of hundreds of square feet of sunlight to be focussed into a very small area, producing lots of heat which can be then very efficently used to generate electricity.
When it comes to energy production though, there is no free lunch and all systems have downsides; some less than others.
Solar will be the wave of the future but it is also going to be some time shaking out.