Tesla Solar Roof: Money Calc

[SageBrush]

Elon has said in the past that the new solar roof will pay for itself over time.
Electrek now reports pricing, so I thought it time to see if I could validate Elon's statement

Assumptions:
12% efficiency
20% generation capacity
Half of roof PV
15% average PV degradation

Calc:

• At $21.85 a square foot, $235 a square meter
• 30 years of sunlight, 5 hours normal a day: 54750 kwh
• At 12% efficiency, 6570 kWh
• At 50% roof PV, 6570*0.5 = 3285 kWh
• 15% degradation, 3285*0.85 = 2792 kWh

Well. If the reported cost includes installation this is exciting stuff. And if not, the material is free which is also pretty compelling.