Some solar generators are big (5)
I believe the answer is:
large
'big' is the definition.
(synonyms)
'some solar generators are' is the wordplay.
'some' says the answer is hidden in the clue (some parts of the word are used).
'LARGE' can be found hidden inside 'solar generators are'.
(Other definitions for large that I've seen before include "Immense" , "Wide-ranging" , "Big, outsize" , "Stout" , "Chunky" .)