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. A maximum value is determined for the amount of liquid to be converted to vapor during a daylight portion of a day as a result of the heat generated in the inner cylinders of the one or more solar collectors. An amount of the liquid is directed into the one or more solar collectors, where the amount is a value that is at least the maximum amount value.