Abstract: A method of converting a liquid into a vapor includes directing liquid into one or more solar collectors through a manifold that supports the one or more solar collectors. Each of the one or more solar collectors includes a transparent outer cylinder having a closed end and an open end, an inner cylinder having a closed end and an open end, the inner cylinder being concentric with and disposed within the transparent outer cylinder so that the closed end of the inner cylinder is located proximate to the closed end of the transparent outer cylinder, an outer surface of the inner cylinder being made of a material that absorbs solar radiation to generate heat, the longitudinal axes of the transparent outer cylinder and the inner cylinder being substantially horizontal, and an enclosed and evacuated space formed between the transparent outer cylinder and the inner cylinder.