This paper provides the results of using an alternative method to calculate annual insolation probability of exceedance statistics (PXX), which are critical measurements for assessing long-term energy yield and valuation of PV systems. This method aggregates ground-based and satellite-based data, thereby increasing annual insolation data sample size and reducing the uncertainty in interannual variability. Overall, the P99 annual insolation values were found to range from -4 to -8% of the P50 value across the continental United States.