NASA has provided a convenient SSE database covering daily ground level solar insolation for the entire planet based on satellite data gathered over 20 years. Using this data and a model for solar insolation at 20km we show comparisons for significant urban locations at latitudes from 23 to 60 north. StratoSolar insolation is just a little less than top of atmosphere insolation which is widely available data, (including in SSE) and a convenient check on the StratoSolar estimates.
A perusal of these charts shows how large and consistent the benefit of StratoSolar is. Desert level insolation is commonly used to optimistically represent solar, but the combination of a desert and a large urban area is rare, and the cost of long distance transmission offsets any benefit. California does not appreciate how lucky it is in this respect. North Africa, the Middle East and Australia are about it. An optimistic world average for ground PV utilization is 15%.
The chart accompanying the graphs condenses the visual solar insolation into numbers and also provides the equivalent utilizations which are useful for estimating actual power from a given PV nameplate power.
By Edmund Kelly