Hey J, you're correct. I spoke with Jane at Sunpower customer service today. They may be telling you that they are, "Premium Dealers," but in Sunpowers case, they only allow their certified dealers to install them. She claims it's because of warranty coverage, personally I don't buy it. I can purchase a $30,000 automobile today, take it home and change the oil, rotate the tires and flush the radiator, but if the vehicle acts up or the radio quits, they still cover it under warranty.
On a note closer to home, we have a 1.6 kilowatt solar array on our garage roof made up of 14 Kyocera KC-120 panels. One of them failed recently, and Kyocera replaced it for me free of charge. I installed them myself 9 years ago, that was okay with them, as is the case with most panel manufacturers today.
Sunpower claims to have the most efficient solar panels on the market today. If their claim that their panels are 18% efficient, than they are correct. Most panles today are around 13%, which means 13% of the suns energy is converted to electricity, and the other 87% becomes heat. The additional efficiency only allows you to produce the same power in a smaller space, there is no cost benefit to it, in fact, I would suggest that their higher efficiency and premium dealer arrangement actually makes their product more expensive per unit power produced. So at the end of the day, you can spend the same, or more money for an array that runs your home and takes up 25% less space on your roof. For most people, this is of no concern. To give you an example, we power our home with our 1.6 KW array, and at 13%, it takes up less space than the roof of our single car carport, about 85 square feet. Most homes have roof structures that are 5 - 10 times this space, this is why most people opt for more popular brands of panels that are easier to find and purchase, might be less expensive, and allow them to do the work themselves. There are dozens of panel manufacturers out there, Kyocera, BP Sharp, Evergreen and Sun to mention a few. If you have the space for a slightly large array, then all of these products can work for you.
I would also suggest that the Sunpower products are leading edge, and aside from the premium cost they can garner for a newer, more efficient product, they are using a technology that nobody else is at this point in time. This sounds exciting, but bear in mind that like anything else that is new and exciting, there may be bugs in the woodwork that until now have not been discovered. I'm personally more of a, "Trailing edge of technology," kind of guy. I like things that have past the test of time, like woodstoves, laundry lines, and multicrystal photovoltiac panels.
If you want to learn more, I'll include some sources below. Otherwise, just google, "Solar Panels," and check out some links to see who is selling what. If you're planning on spending some real money on all of this, I would highly suggest getting a subscription to Home Power Magazine first. If you subscribe, you can go online with your account info to their website and look through old copies. They have some a year or two ago where they compared all commercially available solar panels and their specs. You can learn a great deal in a short time. Good luck, and take care, Rudydooo
Home Power Magazine, Homepower.com
Solar Energy International
Midwest Renewable Energy Association
Great Lakes Renewable Energy Association
American Wind Energy Association