Most installers I've met don't even mention RoI, only payback times. When our HOA purchased solar, I had to do the calculations for them showing that we should not go for the cheapest option with the lowest payback time. We wanted to make a profit, not just earn back our money as fast as possible. We went for slightly more expensive panels. The most expensive panels were too expensive and not worth the extra money. Slower degradation made a difference, but this also allowed them to give a longer warrantee on the panel (30 vs 20 years). Panels that start to produce earlier although it may not be a lot of extra energy, that extra energy is valuable if you do not have 1 for 1 net metering. If you pay more for the power you buy from the grid than you get for the power you put back into the grid, then your peak production is not as valuable as the ability to spread that production over the day. That's a reason why more people should consider using an east-west configuration.
Most installers I've met don't even mention RoI, only payback times. When our HOA purchased solar, I had to do the calculations for them showing that we should not go for the cheapest option with the lowest payback time. We wanted to make a profit, not just earn back our money as fast as possible. We went for slightly more expensive panels. The most expensive panels were too expensive and not worth the extra money. Slower degradation made a difference, but this also allowed them to give a longer warrantee on the panel (30 vs 20 years).
Panels that start to produce earlier although it may not be a lot of extra energy, that extra energy is valuable if you do not have 1 for 1 net metering. If you pay more for the power you buy from the grid than you get for the power you put back into the grid, then your peak production is not as valuable as the ability to spread that production over the day. That's a reason why more people should consider using an east-west configuration.