Thermal and solar absorptances are only considered in EnergyPlus used when appropriate. For instance when a material surface sees the outside environment, other interior surfaces, etc. Otherwise, those attributes are appropriate - they're ignored at run time, as in the case of conductive heat flow between 2 materials. See: otherwise, see : Input Output Reference. If uncertain, stick to the default values e.g., 0.9 (thermal) or 0.7 (solar).