After ~1.5 months of research and estimates from 6 vendors. I came to agreement on price with a vendor today. System specs are:

Option 1 : SE6000
System Size: 4500 kW
Panels: 15 LG300
Inverter: SolarEdge SE6000
Total Cost $18140 (includes $2500 service panel upgrade)

PV System Cost (pre-tax credit) = $15640 ($3.48/W)

Option 2 : SE5000
System Size: 4500 kW
Panels: 15 LG300
Inverter: SolarEdge SE5000
Total Cost $18005 (includes $2500 service panel upgrade)

PV System Cost (pre-tax credit) = $15505 ($3.45/W)

While I've posted price, equipment, and $/W up front. I would caution anyone in the vendor selection process to be wary of focusing solely on finding the lowest price and equipment selection without consideration of the installation quality. The best way to avoid a cheap solar system is paying a cheap price. Or buy cheap, buy twice. I focused first on vendor reputation (yelp, this forum, solar reviews.com, angle's list), credentials (license(s) held), company history (years in business), and references. Only after narrowing the pool of vendors to those I felt would do a quality installation did I start working toward the best price. For this and most things in life, everything is negotiable.

Interestingly, the vendor that I ended up choosing had one of the lowest estimates that I obtained. Finding low prices is easy, but sifting them through them to identify a quality installer requires more effort. One thing I did is I actually asked references if I could visit their home and evaluate the installation quality myself. In another topic, http://www.solarpaneltalk.com/showth...manship-Photos , I posted the installation work of two vendors... one which is clean and professional (the vendor I choose) and the vendor leaves much to be desired. Both were very similarly priced.

I ended up going with a vendor with a base of business in C-10 electrical contracting (as opposed to solar only C-46 vendor). My theory is that electrical contractors have a longer company history than recently started solar only businesses and have something to fall back on when the solar tax credit dries up in a couple years and the pace of solar installation slows.

My only gripe with the vendor was that the sales guy would not budge on their $2500 price tag on the service panel upgrade. I posted a whole thread trying to reconcile this price. In the end, I was able to get the vendor to come down $700 on the overall cost.

The vendor will be sending someone out to do a site survey (measure the roof) next week. Assuming that goes well, the contract will be put in place a couple days after that. The vendor has 26 jobs currently and 3 installation crews. The projection is Jan or early Feb to have my system up and running.

Will update as they come...

NOTE: My vendor initially quoted the service panel price as $2500. During price negotiation the vendor reduced the overall system cost by $700, but it wasn't clear if he was reducing the service panel price to $1800 as he was adamant about the $2500 price initially. Further down the road when I was considering not upgrading the service panel review of estimates revealed that the vendor was clearly assigning $1800 to the price of the service panel upgrade. --- It's interesting to consider that assuming service panel upgrade is included in the overall system cost, a higher price assigned to the service panel upgrade reduces the $/W cost. Something to consider if you know you require a service panel upgrade and vendors are quoting different prices on the cost. The majority of the bids I got were $1500 for the service panel upgrade, $1800 from one vendor (which this one eventually matched), and the $2500 initial price from this vendor.