Why one would want to practice a Spin solo is beyond me. With an instructor yes by all means but never solo. Agree with several of the above posters - recipe for disaster. Always be aware of the recovery technique though. The PFL I cant really see a problem with whilst solo once it is in a quiet non-built up area with little traffic. The chances of getting a real PFL whilst solo maybe quite low but still most likely higher than encountering a spin.