[nick222226]

It's not so simple to look at one constraint for a rooftop install. When planning an install, cost per watt and watts per square meter interact, as does module size, module weight, low illuminance performance, durability and degradation, appearance, and other factors.

[jeffbee]

It is also true that cost per watt is not entirely intrinsic. If a technology finds a niche, then the cost drops.