Solar Scale, revisited

I wanted to look at the solar scale issue again with a few more fundamental numbers. If we start with (round numbers) 4 PWh per year consumed in the US (EIA), a rough estimate for max solar flux of 1kW/m^2 (also rounded). Typical solar cells today are delivering 10-18% efficiency. However, that doesn't mean a panel deployed will generate 150W/m2. There are issues related to latitude, weather, day-night cycles, etc. This multiplier is called the capacity factor and varies in the US from 10-20%.

So lets be OPTOmistic. 20% efficiency, 20% CF (say Arizona), storage systems and grid efficiencies that allow unity transfer to load. Just doing that math gives us 4500 sq miles of this manufactured material.

Now lets add numbers for oil, as a proxy for conversion of transportation to electric. Roughly 12PWh of power is consumed in oil. Roughly 12% of that is aviation, which we'll assume can't be electric for awhile. So lets say 10 PWh. That would entail an additional 11,250 sq mi for a total of ~16,000 sq miles.

This is better substantially than my previous estimate, but also is a very idealized number. Realistic impact of grid efficiency, real distributed nature of sources, not to mention energy storage issues in order to realistically deploy the technology and you can easily get to double this number. Ultimately, this speaks to a more limited use of solar as a distributed, point of use, supplement at peak demand periods (mid day) and use other technologies for 'base load' technology.