Clearly explain why the maximum efficiency of a solar cell is only ~33%. What ar

Question

Clearly explain why the maximum efficiency of a solar cell is only ~33%. What are the losses? Why can we not have 100% fill factor (even after ignoring all resistive losses)? B. Calculate the short circuit current and open circuit voltage in a GaAs solar cell which is subjected to a monochromatic light of 620 nm. Assume an absorption coefficient a = 1E4/cm; the absorbed photon flux is (1-exp(-at)|. The thickness t of GaAs is 2 micrometer, reflection losses are 10%; 10% of the generated current is lost because of recombination. The power in the monochromatic beam is 100 mW/cm^2. The diode Jo is 1E-19 A/cm^2.

Explanation / Answer

In solar cell one semiconductor material only used. i.e. one p-n junction per solar cell that converts photons into electricity.

When the material is abosrbing photon and it will emit electrons for generating electrons. During this process, the photons which has the energy above band gap only utilized and remaining cannot make the cell to emit the elctrons. So the absorbed photons will be converted as heat energy. this is approximately 47% of the energy of photons.

Solar cell is not 100% opaque material o about 18% of the photons pass through solar cell.

Some of the photons will be lost in recombination of electron hole pairs and the number is about 2%.

Now the remaining 33% of energy is converted as electricity as per theory of William Shockley and Hans Queisser

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