In the northern hemisphere, a roof face pointed south generally produces the most over a year, because that is where the sun spends its day. East and west faces still produce, just on a different curve, with an east face doing its work in the morning and a west face in the afternoon. A north face is the hard case, and on a steep roof it is usually not worth covering at all.
Most houses are not tidy about this. Roofs get built to face the street, not the sun, and plenty of homes on the Wasatch Front have their best exposure broken up across two or three planes. That is normal, and it does not disqualify you. It does mean the design conversation gets more detailed, and it means anyone naming a system size before looking at which faces you actually have is guessing.
How steep the roof is changes the angle sunlight strikes the panels and how the array performs across the seasons, since the sun rides much lower in winter than it does in summer. Pitch also drives practical things that have nothing to do with physics: how readily snow slides off after a storm, how difficult and how safe the roof is to work on, how much scaffolding or fall protection a crew needs, and what the finished array looks like from the street.
Pitch is rarely the thing that kills a project on its own. It is one input among several, and it interacts with direction. A shallow pitch is more forgiving about orientation, while a steep roof makes direction matter more. This is exactly the kind of thing a designer should be able to explain to you in specifics about your house, rather than in generalities about roofs.
Shade is not a yes or no condition. It moves across the roof through the day and changes with the season as the sun's path shifts. A chimney, a taller neighboring house, a power pole, or a single mature tree can each take out part of the roof at particular hours. What matters is which faces are shaded, when, and how much of the year.
The part that gets left out of sales conversations is that trees grow. A tree that clears your roof today may not in several years, and by then the array is already installed. If there are trees on the sunny side of the house, raise it early and ask directly what the plan is: does the design avoid those areas, are you willing to trim, or is that shade simply accepted?
The number that matters is not the square footage of your roof. It is the unshaded, correctly oriented area left over after vents, plumbing stacks, skylights, valleys, dormers, chimneys, and the setbacks your jurisdiction requires are all subtracted. On a cut-up roof with several small planes, that remainder can be a surprisingly small fraction of what you would estimate standing in the driveway looking up, which is exactly why the estimate should not be made from the driveway.
This is also why a satellite outline is a weak basis for a design. Overhead imagery flattens obstructions, misses small penetrations entirely, cannot show you how shade crosses the roof over the course of a day, and tells you nothing about the condition of anything it photographed. As a starting sketch it is fine and most companies use it that way. It is not a measurement, and a firm proposal built only on imagery is telling you something about how that company works.
If the covering is near the end of its life, it usually gets replaced before panels go on. The reason is mechanical rather than sentimental. Panels are attached through the roof, so reroofing under an existing array means paying somebody to take the panels down, store them, redo the mounts and flashing on the new surface, and put everything back. That is a cost you can avoid entirely by handling the roof first, and it is the most common expensive regret in this category.
Get somebody on the roof rather than relying on a photograph. If the only person telling you the roof is fine is the person selling you solar, get a separate roofing opinion. Two independent answers are worth more than one confident one, and this is the single decision most likely to cost you money later if you get it wrong now.
Panels are attached through the roof covering with penetrations, and every one of them has to be flashed properly for the material it goes through. That detail is invisible from the street, invisible in a proposal, and entirely determinative of whether your roof stays dry. Ask how mounts get flashed on your specific covering and who is responsible if one leaks.
A visit also covers the parts of the project that have nothing to do with the roof: your electrical panel and its capacity, the run from the array to your service, and whether a detached garage means trenching. Combine that with a full year of your actual usage and you have the basis for a real estimate. Anything less is a template with your address typed into it.
Not necessarily, because most houses have more than one roof plane, and the design would simply use the better ones. It does reduce your usable area, which affects how much of your usage an array can realistically cover. The honest way to find out is to have someone measure what your other faces offer rather than assume the whole roof is out.
Both are worked with regularly, but the mounting and flashing methods differ from asphalt shingles, and not every crew handles every covering equally well. Ask specifically what mounting method they use on your material, how many of those they have done, and how the flashing detail works. A vague answer to a specific question tells you something.
Treat it as a sketch. Imagery can suggest whether a roof is worth a closer look, but it cannot measure obstructions accurately, judge condition, assess shade over a full day, or tell anyone what shape your electrical panel is in. If a company is willing to write a firm proposal without ever visiting, that is worth noticing.
A few details about your home is enough to start. Or call 801-644-9000 and skip the form.