Also, the use of commonly available solutions contributed to cost reduction.
Which synonym, term or phrase can I use instead of 'the use of' to create a sentence?
I would say:
Also, the implementation of commonly available solutions contributed to cost reduction.
Employment might also be OK but it sounds a bit weird. Kind of depends on what the "solutions" are.
You could also say "making use of", "using", "the employment of", or "employing" (which doesn't sound weird to me, personally), "the application of" or "applying", "availing oursevles of", and "the adoption of" or "adopting", among others.
With no disrespect to user3169's position (there's no real right or wrong here), "implementation" sounds like it has a slightly different flavor of meaning to me, having a sense of "installation" which "use" doesn't. Perhaps it's a bias from my profession (I'm a software developer); we implement solutions by designing, creating, and delivering them. So, implementation has a rather narrow meaning in my profession.