Dear Vanita Nigam, The most suitable method for the extraction of essential oils is hydro-distillation of use of supercritical fluids. However, various maceration or lysis options can improve the recovery of essential oils, I am not sure how you are applying solar energy, if you are applying it as source of thermal energy then u should follow other steps like already done for the hydro-distillation otherwise provide more detail of your objective
Dear Vanita Nigam, The most suitable method for the extraction of essential oils is of supercritical fluids as use your for better recovery till date investigation please read of supercritical fluids Lab scale