https://www.solarquotes.com.au/blog/solar-energy-payback-myth-mb1409/

More recently, Germany’s Fraunhofer ISE stated the energy payback time of PV systems was around 2.5 years in Northern Europe and 1.5 years or less in Southern Europe, depending on the technology installed. It noted the material usage for solar cells had dropped from around 16 grams per watt to approximately 4 grams per watt as a result of increased efficiencies, thinner wafers and wires along with larger ingots.