The cost of the panels is half the problem - prolly less than half actually. Its the new roof, conduit, drywall repairs, electrical panel, permits, etc. Then theres the incidental environmentals ; diminished output due to your northern latitude, 1979 insulation specs, and 30 YO AC system. All this requires you to put up more solar to compensate for without the return.

Like I said, it will likely require a major remodel to the house in order to be cost-effective. Reducing your demand is half the problem and isnt cheap to fix.

You could probably reduce the cost of the panels just by getting a few neighbors together and negotiating/buying together.

-SS