Does this quote seem way too high?

Well, my uncle from NYC always said stuff around there costs double, but >$5.50/watt is pretty incredible. It sounds like this is a Sun Power system which is the very most expensive of brands. You need to do your due diligence and get some other quotes. Our forum host, solarreviews.com is a good place to find a quality, local dealer.
0% financing is a scam in my opinion.
Admittedly, it sounds like your house has issues, needing roof structure and a service upgrade.... but In my area of Arizona, we would do that job for $20K plus the house repair.

Without getting 3-4 bids it's a guessing game as to whether that's the going rate in your location. Have to love capitalism if the marketplace will pay XX I'll be happy to sell it at XX price.

1.) $355/MO. * 25 YRS. * 12 MO./YR.= $106,500. You sure about that ?

2.) ($60,397- $4500)/10.625 STC kW = $5.26/STC W. Seems high to me, but I'm not in MA. Folks are paying about $3.00/$3.25/STC W or less around here (San Diego) before any incentives. Why Sunpower ? I own a Sunpower system. Good stuff. Other stuff is as good for a lot less $$. The only thing better about Sunpower is their advertising and hype.
3.) What's your array orientation ?
4.) Any shading ?
5.) Roof mount or ground mount ?
6.) What arrangements do you intend to keep snow off the array ? that 53 in./yr. of snow Walpole gets will need removal from the array. It will not all melt by itself.
7.) A 10.625 STC kW array with south orientation in Walpole at a 30 deg. tilt and no shading will yield ~ 15,000 kWh/yr. What factors does the 12,763 kWh/yr. include ? Who did the estimate ? Have you run PVWatts on the project yet ? Vendors usually overestimate by fooling with software inputs and B.S.ing solar ignorant customers. 10-20% oversizing by underestimating output is common around here.
8.) Building permits ? Inspections ? Who did the design/calcs for the joists ? Some jurisdictions need drawings and calcs, sometimes done/sealed by a P.E.

9.) Don't sign anything until you read "Solar Power Your Home for Dummies" a free PDF download on the net. then, do the PVWatts runs. Then, armed with what you learn, get more quotes.

Welcome to the forum of few(er) illusions.

Thanks for all the usefull responses.

Yes, I will need to get another quote or two. And, yes, I will read the "Solar Power Your Home for Dummies".

Solarix, why do you state that 0% financing is a scam? Are you saying it's a shell game?

All the offers of low financing on solar compensate for the low rate by jacking the price way up. The monthly payment is the same (if not worse). Doing this increases the amount of the Fed tax credit (they receive) and could lower the cost to the consumer, but no - they keep the lion's share of the increased profitability and just give the consumer whatever little is needed to make the loan payments less than what their utility savings will be so they can say "you will be saving money every month by accepting our deal". The best thing you can do is shop for the best cash deal you can find, finance it your self, use the tax credits yourself, and you will be way ahead over any company pushing their low interest rate deal. These companies make more profit off the financing than they do off the solar install.

Thanks for spelling it out Solarix. I understand now.

I'm reaching out to a local provider that was recommended to me.

Crazy pricing. A 10.6 kw system with microinverters and racking is under 15-16k without installation. 10-15k for installation plus the 4.5k.