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I've got 200 sq ft of panels; generate 2.8kW in full sun. That's about 14 watts / sq ft. Your 6 x 38 roof would generate about 3.1 kW in full sun. Please note that full sun also means pretty good angles . . close to directly facing the sun. That is; early morning full sun will not produce a lot; because the angle to the sun will not be right. Also know that rated capacity is rarely achieved . . need clear good day and near perfect angle to achieve that full output. These figures are based upon using traditional panels; if you're using the "roofing" PV stuff; their output may be signifigantly different. Again; angle to the sun is important . . and so is not being covered by snow . . or even light shade . . . these can impact output greatly. I've had my system 1 1/2 years now; not sure I ever saw the full rated output from the panels ever. Not that there's anything wrong with them or the system; just that circumstances to produce that do not occur terribly often.

Any "normal" roof angle I've seen, will not lend itself well to good solar output. The sun changes about 46 degrees in "altitude" throughout the seasons; centered about your latitude. I'm in central New York state; here the ideal angle is about 20 deg in the middle of winter; and about 65 deg in the middle of summer. Either of those angles, or anything in between; is NOT typical roof . . .

If you're concerned with getting it done right / well / getting useable power; why not call a renewable energy company . . they can give you GREAT info; especially regarding your local clime / conditions etc. They will also have other installs in the area; which could well serve as examples for the building review board(s) etc. They will also be FULLY versed in generator ( or PV ) hook-ups; including doing it the right / safe way; and meeting all utility requirements . . and knowing how to jump through those hoops too . . . . They will also be able to do an energy budget; finding out what you use, and what you could run from any such system you may install . . sizing it effectively. Another issue may be prospective rebates / incentives that may exist . . many times they are only applicable when the system is installed / designed by a certified installer. In my case; I got about $11k in incentives from the state, and state and fed tax credits totalling another ~ $8k. That helped a lot with this system; they are NOT cheap . . but in the big picture with energy prices rising; paybacks become much more realistic / fast every time stuff goes up . . .

My system is a 2.8kW capacity of panels; I run an 1800 sq ft home from it and am tied to the grid to sell back my excess. I generate about 85% of my total electricity needs on an annual basis . . .

Get in touch with some pro's . . before you get too far along . . .

Bob

Bob -- Thanks so much! This is very encouraging. FWIW, our main roof is 10/12 pitch and I suppose we can build the loggia roof whatever pitch we want. We own a snow brush, too! I hear you about the angle of the sun and difference between first light and high noon. It does sound like we could do this!

May I ask what your total cost was, before rebates or credits? Illinois has a powerful coal lobby and no meaningful incentives, but I think the Feds still have something for another year or so.

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My initial raw cost . . no rebates / full installation / all utility issues / permits / inspections etc was early 30's. I'll add that I chose to have battery back-up which was extra money for batteries and attendant stuff; and that my location etc dictated two pole mount arrays about 200' from the house . . which also added signifigantly to cost . . .

Again; your specifics of site and your needs ( what you want to accomplish ); will have a big impact on things.

Did some quick figures of your latitude; about 41 degrees. Optimum angle year round is therefore 41 degrees roof pitch; that's about 14/12. Minimum angle ( peak of winter ) is about 18 deg; or 37/12 pitch. Maximum angle ( peak of summer ) is about 64 deg or 6/12 pitch. You can't move your roof . . but this points out that angles do change a lot. This is why it's common to tilt "fixed" panels a couple times a year. Steeper angle in winter helps optimize what you get then; when days are shortest. It also helps a LOT to shed the snow without the need to shovel / sweep. It also means less output due to improper angle; for the remainder of the year . . . .

Good luck with your endeavor; I'll be curious what you end up doing . . . .

Bob

Thanks, Bob. I've emailed three companies and am waiting to hear back.

From what you wrote, I'm wondering if the standing seam roof is going to work for me -- can't change angles. Maybe the area will be large enough to provide the "emergency" power I want, despite the lessened reception.

I think I have to use standing seam to get this past my suburb's picky appearance board.

I recommend that you look at the listing of Full Service Installers from Wisconsin. Many from the Southern part of the state may be willing to drive down to you.

The Iowa energy office has a listing of Illinois solar installers. Google them.

see link below

Niels

Here is a link that might be useful: WI full service installers list