P50 and P90 are probabilistic scenarios, used for managing and understanding the risk of variable weather conditions, where the number denotes the percentage of years that will exceed that value. For due diligence and solar resource assessment, having multiple probabilistic scenarios is beneficial for better decision making and risk management. TMY P50 represents the median or average conditions, reflecting typical long-term weather patterns while TMY P90 represents a more conservative “low end” scenario, indicating conditions that are exceeded 90% of the time, used to understand the downside risk of a “bad year”. Solcast offers probabilistic scenarios for TMY at any “Pxx” level.