The SPN1 global radiation often is significantly (up to 100 W/m2) higher than Rsw.in on clear days. This could indicate a reflection problem, though without seeing the exact set-up, I can't imagine how reflections would affect only this sensor.
The SPN1 global radiation often is significantly (up to 100 W/m2) higher than Rsw.in on clear days. This could indicate a reflection problem, though without seeing the exact set-up, I can't imagine how reflections would affect only this sensor.