In my 1000 square foot house I spend $1000 a year on electricity. How exactly would I pay for $15K - $20K worth of solar cells in 5 years?
At that price, you would be looking at a 15-20 kW system. You would also have a hard time fitting that many solar panels on a 1000 square foot house, unless you redesigned the roof specifically for solar. A more realistic estimate for your house would be $5-6k for a 5 kW system.
I guess I could go all electric, which would cost me another $5 in appliances.
A new 40 gallon electric water heater goes for $240 and a new freestanding electric range goes for $350 at Lowes. A new electric heat pump (Air Conditioner/Heater) would be a bit more, but still well under $5k (I'm assuming you meant five thousand with your $5 number)
I might break even in 15 years, about the time I would need to replace the solar cells.
Modern panels decrease their output by less than one half of one percent per year, often with a warranty backing up their claims. For example, the SunPower X-Series solar panel warranty guaranties a less than 0.4% decline per year for 25 years. So at 15 years, you are looking at panels that are still producing at least 94% of their original capacity - hardly needing replacement.
By then they should be cheeper and more efficient. So yea by about 2030 solar would probably take care of my needs.
Solar panels will continue to get cheaper (a few cents per watt) as production scales up. They will also get a bit more efficient (a few percent) as manufacturing processes improve. However, don't plan on any disruptive technology advancements to occur in the next 15 years that fundamentally change how home solar installations work.