What is the pool water temperature gain displayed on MyDualSun?

The simulation report of a direct solar pool heating project with MyDualSun displays a temperature gain in °C.

This estimate is the result of a difference between :

• the estimation of the average temperature between April and September without solar heating,
• the same estimate with solar heating. 

This data gives an estimate of the "average" temperature gain provided by the DualSun solar panels compared to the same pool without any heating equipment. 

This value is an average and is not taking into account specificity such as overflowing swimming pool, under exposed to sun pools or over exposed to wind. 

These temperatures are estimated thanks to the TRNSYS software which is the calculation engine of MyDualSun.

How are the yields of panels calculated in MyDualSun?