We begin by analysing the solution-phase morphology of multichain systems of P(NDI2OD-T2) in "good", intermediate, and poor solvents. Aggregate properties and the kinetics of aggregate formation were analysed in a number of ways. For all analyses, two chains were considered to be in the same aggregate if any of their monomers had a backbone centre-of-mass separation of less than 7 Å. In all cases, aggregation occurred through interactions of the NDI groups (CG site types 2, 3, and 6) in the π-stacking direction. This highly anisotropic aggregation behaviour is consistent with expectations for conjugated polymers, whose attractions in the π-stacking direction are substantially stronger than via the alkyl side-chains, highlighting the importance of accurately capturing the shape anisotropy of the monomer unit.