Why are the best solar cells only 12% efficient? What's the technological impasse?

Answer 1

Because energu conversio depends on what form of energy is going into what form ...remember work can be conveted @ 100% efficiency to heat ...but heat cannot be converted to mechanical work with 100 % efficiency . ENTROPY plays a role here !


Same is true with the energy in photons to it's conversion into electricity .Entropy is involved !

Ok lemme be a little more clearer ; it is easy to convert an organised form of energy to a disorganised form of energy ...like heat is a disorganised form of energy compared to let's say mecanical energy ...it is difficult to convert disorganised form on energy into organised form ...(this a result of 2nd law of thermodynamics)...now photons are disorganised & electricity is more organised form of energy in loose terms ...so it's impossible to get 100% conversion ...but it can be improved by significant amnt by using good & efficient material ...so it's not a tachnological impasse rather a physical law empasse !! 100 % Not possible !
Hope this helps

Answer 2

There are theoretical limits to the efficiency of the solar cells (photovoltaic - PV) that are around 50% depending on the type of cell. Some laboratories have demonstrated single cell efficiencies a little over 20%. However, each cell is slightly different and by the time they are wired together in modules they lose a significant amount of power. Also, temperature has a huge effect so that most PV modules are much less efficient than claimed by the manufacturers. Besides this, there are losses when the modules are wired together and more losses when the power is inverted to AC for use by your home or the grid.

There are some new technologies coming that have much better efficiency though. Solar concentrators with Stirling engines (See http://www.infiniacorp.com ) concentrators with high-efficiency PV, and continued improvements to common PV panels.

Answer 3

Whatever we do there is an efficiency factor invloved.
Energy get wasted hwere we dont have any control over.

Like the when you place a solar cell in the sunlight you can not capture all the sun light , part of it get reflected. you can get the percentage of this waste. Then part of it is used to heat the solar cell. this also a waste. Then the process that converts the photon in to electricity has its own efficiency of conversion. When all the losses are accounted for only 12% seems to be left.

In automobile engines we dont get all the heat value we put inb the tamk. Only 5% we use. everything else is wasted. That is the way of life

Answer 4

Solar radiation comes in a variety of wavelengths. Solar cells require radiation of a particular wavelength to operate: photons of a longer wavelength do not have enough energy to move an electron, while photons of a shorter wavelength can move an electron but all the energy of the photon beyond the minimum is wasted. This would not be a problem if the cells could be made cheaply enough, but at the moment they can't. A solar plant costs about ten dollars per watt; half for the cells and half for batteries and electronic equipment. The maximum energy that can be generated per watt of installed capacity is two kilowatt hours per year: you have 4000 hours of daylight, but because of the cosine rule (most of the day the sun is not shining directly on the cell) you can usefully get only half that. Two kilowatt hours are worth about 25 cents; your money is better off in a savings account unless you must have solar because you cannot get mains power.