Could the levelized cost of energy (LCOE) be considered an appropriate metric to account the "costs for a conplete system to provide electricity for a population"?
https://en.wikipedia.org/wiki/Levelized_cost_of_energy
Here's a Wikipedia page on cost of energy per source (in LCOE) that has a table of sources for Germany. According to it, solar is 37-115 €/MWh, while CCGT (gas) is 78-100 €/MWh:
https://en.wikipedia.org/w/index.php?title=Cost_of_electrici...