Opinion on PV System

I'd be grateful if you could help me.

I think I am ready to pull the trigger on a system in Massachusetts. I did a lot of research, but will be spending a lot of money and I'd like your opinion as to if this seems a solid system and if the price is in the ball park. I got two local companies evaluate my site. we worked through a system to meet 95% of my needs and both companies priced it with similarly within a few hundred bucks. I wanted to go with a bigger system, however.

Goal: Grid-tied, roof mounted solar PV to meet the majority/all of my electricity needs now and have room for the addition of an electric car in 4-5 years.

My site is south facing, most of the roof where the panels would fit would be at 28 degrees, four panels would be at 55 degrees. They calculated I'll get about 82% sun year round, this is after I had a tree taken down and a few branches trimmed. I'm told the Tigo maximizers will not only help with efficiency, but also prevent shade on one panel from killing the rest of the panels production. I was told that microinverters are not suitable for the 327 Watt panels. I talked to one guy who had a set up like this for a year and he was happy with it.

After several questions and a few revisions below is what seems to be the best. I haggled with this company after the initial proposal and got them to knock 1,000 bucks off. Below is the final price.

"5.56kW Photovoltaic system:
17 SunPower 327 watt High Efficiency photovoltaic modules, 1 SunPower inverter, 17 Tigo Power Maximizers, and all necessary balance of system materials (racking, wiring, disconnects, etc.). This price for complete, turnkey installation including all permits and rebate paperwork.


Gross Price $37,895
Less Commonwealth Solar II base rebate* - $2,000
Less CSII Moderate Home Value Adder rebate* - $2,000
Less anticipated 30% federal tax credit* - $10,169
Less anticipated 15% state tax credit* - $1,000
Total anticipated cost after rebates and tax incentives: $22,726


The above system would produce approximately 5,600kWh/year, which is an estimated 128% of your current electricity consumption. The anticipated payback period is 6-9 years and this includes the electrical upgrade to 200A service."

The last 2 years I've consumed between 4.25 and 4.5 MW annually.

Massachusetts allows solar home owners to sell SRECs. This year they are going for about $500/MW. The ceiling for the program is $540 /MW this year and next. The price will go down over time, but the floor is something like $170/MW and I'd be in for 10 years.

The company also told me to figure that I'd spend some cash to replace the inverter in ~15 years.

Thanks.