Uninsulated pipes of solar waters heaters in Israel increase national electricity consumption by 200 millions kWh/year, 40 millions USD per year. Simple solution having 2-4 months return of investment period can stop this waste.
This work introduces energy balance of thermosyphonic solar water heater (SWH) without pipes' thermal insulation. The results are used for economic evaluation.
Thermal insulation of SWH is required by solar legislation in Israel and national standards. Actually there is not any insulation on SWH pipes. Outside pipes' thermal insulation, if installed, is completely damaged after 1-2 years. Pipes inside buildings usually are in sleeve made of plastic pipe used for electric cables. Plastic sleeves on hot water supply pipes are good equivalent for thermal insulation. However lack of insulation or sleeve on outside circulation pipes increases need for backup resulting in huge national cost.