Hello. I just bought a Bluetti SP200S solar panel. I have two of the old SP200 solar panels. Would appreciate if someone would tell me if this SP200S will be compatible with the old SP200 panels?
Nobody will be able to give you a specific answer. There are too many factors involved and every use case is different. Just try it out for yourself and let us know the result. 
Hi @QuirkyQuest the panels need to be identical to work properly the panels have different ocv and amps so either go with the single or but another pv200 or pv200s.