According to Wikipedia the worldwide consumption of electricity is about 21k Tera watt hours. That's 21,000,000 gw so it's .001% right? Also I think cost is now about a quarter per watt
- The number of hours in a year.
- The percentage of nameplate capacity that the system can be expected to produce on average, e.g. the capacity factor.
There are 8760 hours in a year. A solar PV system in a sunny region may have an annualized capacity factor of 25%. (Installations in really sunny regions may achieve upward of 30%, and Saudi Arabia certainly has a lot of sun, but dust offsets some of the benefits of sunny deserts.)
200 * 8760 * 0.25 = 438000 gigawatt hours of electricity generated per year, e.g. 438 TWh, or about 2% of present annual global electricity generation of 21,000 TWh.