Hi there, I believe that you already have an entry for solastalgia. But, just for the record, this is what I think it means:

Solastalgia has its origins in the concepts of ‘solace’ and ‘desolation’. Solace is derived from solari and solacium, with meanings connected to the alleviation of distress or to the provision of comfort or consolation in the face of distressing events. Desolation has its origins in solus and desolare with meanings connected to abandonment and loneliness (isolation).

Desolation and solace are among the very few words in English that closely connect psychological and environmental states.  Desolation and its meanings refer both to a personal feeling of abandonment (isolation) and to a landscape that has been devastated. The word solace also relates to both psychological and physical contexts. One meaning refers to the comfort one is given in difficult times (consolation) while another refers that which gives comfort or strength to a person. A person or a landscape might give solace, strength or support to other people. Special environments might provide solace in ways that other places cannot.

If a person lacks solace then they are distressed without the possibility of consolation. If a person seeks solace or solitude in a much loved place that is being desolated, then they will also suffer distress. In both contexts there is anguish or pain and the ‘algia’ (pain) in nostalgia is equally applicable to the pain in this context

In addition, the concept has been constructed such that it has a ghost reference or structural similarity to nostalgia so that a place reference is imbedded. Hence, literally, solastalgia is the pain or sickness caused by the loss or lack of solace and the sense of desolation connected to the present state of one’s home and territory. It is the ‘lived experience’ of negative environmental change or the homesickness you have when you are still at home.