The screening enters both the calculation of the quasiparticle energies (and with that the free transition part of the BSE) and the electron-hole interaction kernel. The individual effects can be distinguished from the data shown in Figure for solvated MCP. Without environment screening, the excitations are found at higher energies in the subsystem calculation as compared to the full reference. This is a combination of too large quasiparticle gap and too strong electron-hole interaction when the environment screening is not accounted for. One can see that when environment screening is included on GW level only the BSE energies are obtained several 0.1 eV below the referencethe free transition part is almost correct, so the deviation can be attributed to too strong electron-hole interaction. Only when the latter is also additionally screened, a very good agreement with the full system reference can be observed.