Solar radiation threshold of LB Passive Strategy Parameters Component

Hello.
I have a question about the LB Passive Strategy Parameters Component.

Does ‘Outdoor solar flux’ in ‘solar heat cap’ mean the solar radiation on the south-facing surface?
Also, why is the default value set to 50W/m²?

About passive strategy, ASHRAE defines the solar radiation required on the south-facing surface to raise the temperature by 5.56°C as 157.7 W/m².
If it does mean south-facing solar radiation, I think this parameter should be input as 28W/m² (= 157.7 / 5.56), which is the amount of solar radiation needed to raise the temperature by 1°C.

Thank you in advance for your help.