In terms of conversion efficiency, what is the relative increase of performance by comparing tandem amorphous-nanocrystalline and a-Si:H solar cells (in %) ?

Answer :

The amorphous- nanocrystalline solar cell and hydrogenated silicon solar cell can be compared either by using realized or  theoretical converison efficiencies. Here we are compairing using realized values of conversion efficiencies.

The realized maximum conversion efficiency for a amorphous -nanocrystalline solar cell is apprximately equal to 7%.

Similarly for a hydrogenated silicon solar cell , the maximum realized conversion efficiency is equal to 10.2% .

Now , for performance comparison we need to calculate % increase .

So , % increasing = (Increased value / smaller value)*100

here increased value = 10.2 - 7 = 3.2% and  

Smaller value = 7 %

So , % increasing = (3.2 / 7)*100 = 45.71 %

Now , the % increase of performance or relative increase of performance in %

= (100 - 45.71)% = 54.295 %

i.e. hydrogenated silicon (Si:H) solar cell is  54.295 % more efficient than amorphous -nanocrystalline solar cell

Note : The difference between a quantity increasing and its increased value should be clearly understood.