Typically power is priced by Levelized Cost of Electricity (LCOE) where you amortize the total cost of ownership across the total power generated to get a per kwh cost which is what most grid operators care about. After all, large scale investors and governments don't care if a plant costs a billion dollars if it produces 20 billion in electricity.

https://en.wikipedia.org/wiki/Levelized_cost_of_electricity

What you are talking about is the Payback Period (PP) or Return on Investment (ROI) which is more important to homeowners adding a solar plant to their homes.

Both of these types of measure take into account both capital and operating expenses.

LCOE is a terrible metric for the power grid because it does not capture the cost of balancing the power grid.

Excess renewable power is great but it creates a problem and the cost of that problem is not borne by the generators that created the problem.

What LCOE captures in this context is that solar panels are cheap and that the fuel cost is zero.

The average price of electricity is greatly affected by this, which is why electricity is Europe is generally more expensive than in North America.

Edit - the response below is also incomplete. The trouble with modelling the cost of balancing the power grid is that it depends on many variables, many of which are difficult to forecast. The primary challenge with depending on the weather for power generation is that the climate is changing. What that change looks like in 20 years is impossible to forecast. A great example is from the winter o 2023, during the "dunkelflaute" in europe. Both wind and solar power generation were low for three days.

The estimates for solar plus battery storage typically only account for eight or twelve hours of storage.