Hi Scott,
Just so you know, model 2552 was introduced in 2012. You will not find a 2011 model year (or older) of the 2552.
If model 2551 is an alternative for you, then you can go back to year 2005.
Keep in mind that 2007 was the first year for all models where the whole house inverter and twin house batteries came standard. I thought I had seen them in a few 2006s, maybe introduced near the end of the 2006 PC model year.
I don't know anyone who does not appreciate the inverter and two house batteries.
Ron Dittmer