Backup heating and water heating are the two areas in which the use of a solar collector, or collectors, is especially effective and economical. Used in conjunction with modern buffer storage devices, solar water heaters can efficiently support, or back up, traditional heating systems. In the fall and spring the heating can be entirely or substantially produced by solar energy.

 

A solar water heating system can cost between $2,000 and $4,000, which would constitute about 1–2% of the cost of a one-family home and even less – about 0.5% – of the cost of a multiple-family dwelling. And at that cost such a solar heating system delivers up to 90% of all needed hot water during summer months, and about 50% during the winter – all this at zero energy costs for up to 30 years.