Solar Water Heaters

Today’s solar water heaters provide a reliable, proven, and effective technology. Most obstacles to growth in this industry stem from a false boom in the 80’s generated by the 40% cost-based federal tax credit. Marketing companies offering systems at inflated prices dominated the market and, in too many cases, poor equipment was poorly installed.

New systems cost approximately $2,500 – 3,000 for household usage. At a $3,000 cost to supply 70% of water (with no rebates), payback is:

  • about 9 years to replace electric heating at $.094/kWh

  • about 25 years to replace gas heating at $.50/therm

The industry accepted payback for replacing electric heating is five to twelve years, depending upon system efficiency and household usage. Systems can have a fifteen to twenty-five year life span. While the residential savings per household is small, in the aggregate it amounts to a significant savings overall as water heating is a major demand. As peak always occurs in the late afternoon on the hottest summer days, solar water heaters can provide a 0.4 kW/household peak saving.

Commercial applications can take advantage of economies of scale in equipment and labor and produce a much quicker payback. Hospitals, cafeterias, car washes, large laundry operations, even schools tend to have a large enough hot water demand that the bottom line will look good when replacing electric heating.

Cities could exploit this potential energy savings by

  • Adopting an ordinance for new construction eliminating the installation of electric water heaters, except as back up supply or as an integral part of heat pump, on-demand or tank less water heaters.

  • Ban the use of pilot lights – use electric igniters.

  • Adopting an ordinance governing solar water heater installation standards, such as the 1988 Uniform Solar Energy Code of the International Association of Plumbing and Mechanical Officials. note A licensed plumber should be required to attach the system to the city water supply.