I propagate two Sun orbiting s/c and expect identical results.
1) SC 1. Canon-ball SRP, area=500, mass = 1000 kg, Cr=1 (absorption)
2a) SC 2, SPAD SRP, mass = 500.
2b) S/C attitude set so that s/c body X axis points towards the Sun. S/C to Sun unit vector should always be (1,0,0) in the s/c body frame. (equivalent to RA=DEC=0 in the SPAD file).
2c) In the SPAD file, I set the Area vector to 0 unless the dot product of the SA normal (s/c body X axis) and the s/c to Sun vector is > cosd(0.01).
The difference between the two propagations is 0. (for future runs, may want to use 1 degree as cutoff to avoid roundoff errors)