It wouldn't exactly be "nearly free" until one at least breaks even from the cost of the solar panels. I imagine for the average house it would probably take about eight years to do so even with typical federal, state and/or local solar incentives.
And you would be remarkably wrong, but don't feel bad--a
remarkably large number of people don't understand the solar panel value proposition, nor understand the risks posed by a century+ of uncheched GHG dumping either.
Scary indictment of our educational systems as it's third-grade math, at best.
In our case, breakeven was ~16 months.
Our system was an absolute steal: $8k for a ONE-PAYMENT, 20-year lease.
The house
was using about $2k/year in electricity.
Each car in the garage (two) was using about $2k in gasoline per year (and far more cost in oil changes, maintenance, etc.), so that's another $4k. (Those ICE cars were replaced with two Teslas, which are charged with sunlight.)
That math adds up to $6k/year in previous, now avoided, costs.
The PV system cost $8k.
So, in just over a year the PV system paid for itself, and EVERY YEAR THEREAFTER is allows us to pocket $6k, with the side benefit of helping leave a usable planet for other generations.
For argument's sake, let's assume we had to pay TWICE as much for the solar panels, say, $16k.
Now the breakeven is, OMG: TWO AND HALF YEARS!
Then, after 30 months, you begin to save $6k every year for the next few decades . . . .
Third-grade math folks.