Solar water heating (SWH) is a technology that every homeowner can use to save on electricity bills. In a year, the average household of four will consume enough energy to heat water to fuel an intermediate sized car for 20,000 miles, and modern systems are not only efficient and cost effective, but also extremely reliable.
 A solar water heater uses the sun’s energy to pre-heat household water before it enters the conventional gas (or electric) water heater. Because Southern Spain is blessed with such sunny weather, a solar water heater could generate up to 90% of your annual water heating needs.
There are two types of water heaters, but the bulk of systems installed in Southern Spain are ‘active’ because they are considered to be more efficient, and should provide more than 20 years’ service.
 Solar water heaters are always installed in addition to your regular water heater. That means that even during bad weather, you will still have hot water. To maximize your savings, you should attempt to use the most hot water in the late morning and early afternoon when the solar system is operating at its peak. Also, it helps to spread your cleaning load over the week. For example, instead of washing seven laundry loads all at once it would pay to do one a day. This will reduce the amount of water your regular water heater must heat.
Solar heaters vary in cost from around €2,000 to €6,000, depending on the size of the family to be served (and therefore the amount of heat required);  the size, type and brand of solar system;  the type of roof upon which the panels are mounted; the building code requirements and orientation of panels. Savings depend on the size of the system and the needs of your family and the way you currently heat your water. The average annual cost for water heating is usually over half the annual gas bill. Typically, one person uses between 15  and 25 gallons of hot water a day, which can cost €5.00 to €25.00 per person every month, so a family of four could be spending between €384 to €1200 a year just for heating water. A gas bill is charged at varying rates or tiers, and the most costly level or tier is levied in winter, when you are using the most gas. A solar system can reduce your daily gas consumption and thus you will be purchasing the less expensive Tier 1 or “Lifeline” rates.
The ‘payback’ from solar heating varies from four to 10 years, but it may be more useful to think of solar as an investment which  yields an annual return, much as a bank savings account provides interest. A solar water heater will generate savings that can equal a bank account generating a 20% annual return.  You may prefer to pay the utility bill forever, or you may wish instead to go solar, and become your own utility. It is simply the best investment available today because it guarantees a return on money that you will otherwise “burn” and helps you develop equity as you bank your savings.