Thanks for the comments.
1. It may not be specific, but it purports to show actual savings. You can't have it both ways.
2. The Project Sunroof profile assumes a cash investment. There are no interest payments included. Invested assets have income value, but the profile totally ignores that fact, but cranks in an inflation increase in electric costs every year. Invested assets could easily overcome inflation.
3. I am just saying that a 20 year old solar system will not be worth what you paid for it. But, invested assets will maintain their initial principal amount forever.
4. A lot of people in The Villages don't have a choice about replacing their roof. Their insurance company requires it, usually at 15 years.
If you are selling solar as a way to save money, then do an apples to apples comparison.
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