In the case of solar panels, I presume g/CO2 refers to the energy taken to create the panels, from mining to manufacture to transport. This then begs the question: how long are the solar panels presumed to last?
“This then begs the question: how long are the solar panels presumed to last?”
20 years, before they start losing efficiency, but they would produce a fair amount after that as well. See my post # 4.