In MA, if you want to get the MA Grant and SRECs, (and you do), you have to contract with a MA CEC approved installer, (literally hundreds), and you have to get a Mass Save home energy audit done first.
I took 17 proposals for a 6.72 kW ground mount array with Enphase in 2012 and the qoutes ranged from $31k-$45k, all the higher end being national companies with large sales forces and high overhead, and all the low end being locally owned and operated.
Compare your qoutes to Absolute Green Energy in Worcester.
'12 SL last reading @ 2 yr, 22k, 260 GIDs, 62.35 Ahr
'15 SV w/QC, Mfd 5/14, Leased 8/14, 292 GIDs, 64.38 Ahr when new
@ 36 months, 34k, 270 GID, 57.49 Ahr
'17 Bolt LT
6.72 kW Array