No, QMC has not stated QE for solar, but efficienc

No, QMC has not stated QE for solar, but efficiency is relative to the context as you say, "I know the story on LCOE & how efficiency numbers don't matter & all that," You also know that BOD member Dr Ghassan Jabbour would head up the R&D and he is ultra-expert on QD and printing QD by R2R. Only he knows how long from concept to first commercial production. I won't guess.

I just quoted that India is paying $740M/GW on the other board. I have said Solterra could do it for 5X less, or app. $150M/GW.

The factors or variables include-
CAPEX - how much to construct and
OPEX - how much to operate

Answer - Compared to Silicon Solar Panel production, Capex and Opex are nothing.

Solar Cell Efficiency -
Cost of Materials -
Speed of Production -
Value of End Product increased by QD -
Regionality concept

Answer -

Solar Cell Efficiency - if the cost of production is 5X lower for the same amount of watts, then the efficiency is only relevant relative to siting, and if siting on a solar farm, it is of no consequence. The cells will not be 5x less efficient.
Cost of Materials - I foresee that each solar factory could have its own dedicated CFP machine so costs of production for QD would be very low.
Speed of Production - The R2R would start at 100meters/minute and increase to a maximum of 600meters/minute. That info is per the R2R makers.
Value of End Product increased by QD - That is Solterra's profit.
Regionality concept - Licensing franchises by region - low risk, repeatable profit.