Currently any new solar panel systems produce SRECs for a period of 10 years. However, as of June 20th, that period will be reduced to 8 years. This change was written into the original Commonwealth II solar documentation and was triggered by the current oversupply in the SREC market. The state may step in and prevent this change from going into effect, as it did when it changed the SREC requirement, but that is purely speculation – I have not heard anything one way or another. How much this will affect sales of new solar systems after that date remains to be seen.
More information can be found in SRECTrade’s blog post Massachusetts 10 Year Opt-in Term Deadline.