Mike Hatfield is leading the team to discover how various sized evacuated tubes perform. (A 6’ tube costs about $2). We have pint, quart, and gallon sized tubes that are all made in China. The surface area/volume ratio affects the effectiveness of heat transfer. Small and tall is the most efficient.

We’re all excited that truly low cost solar water heating is available. The vacuum between the two cylinders of glass is amazingly effective at capturing the heat and even without reflectors the water can get hot quickly. We imagine all types of low cost high performance solar equipment being made around the world. A report follows soon!