Dear William,
Thank you for sending the files.
The linear Fresnel and other solar models determine the solar radiation incident on the solar field (or array) based on the solar radiation data in the weather file and solar angles that the model calculates from the hour of year, latitude, longitude, and time zone. For your artificial data with constant radiation values, the solar energy incident on the field varies with the day as the solar incidence angle changes throughout the day. That's why you see the system's electrical output varying with time of day in spite of the constant solar radiation data.
Best regards,
Paul.