Solar, hybrid and tankless water heaters and your choices

With triple digit temperatures last week, we have successfully made the jump right past spring into summer here in the Valley of the Sun. Here, a week of 110 degree weather is considered normal, and hot water during the summer is not a choice, it’s the only choice. Hot water heating can be the second or third biggest energy user in the home, right behind the air conditioner, and saving on water heating can knock off up to 20% of your total utility bill. Using the power of the sun to supply your hot water needs is an efficient method of heating water, but there are even more cost effective technologies outlined below that will keep more green in your pocketbook.

A tankless water heater is preferable to solar water heaters for gas-fired tanks. To prevent cold water sandwiches, tankless water heaters now feature a 20-gallon reserve tank and still heater the water only when needed. Tankless heaters use a sealed combustion venting type that prevents carbon monoxide from backdrafting into the home or garage.

A hybrid water heater is ideal for Phoenix residents, and preferable to solar water heaters if you have an existing electric water heater. The hybrid water heater uses a heat pump, which sits on top of a traditional electric water heater to heat the water.  The heat pump works exactly like your refrigerator or AC condenser, but in reverse. That is what takes the ambient heat out of the surrounding air, and uses that to heat the water and expels a small amount of cool air (perfect for a garage application). Your refrigerator will extract the surrounding cold air and circulate it to provide chilled food while giving off a small amount of heat on the bottom of the unit. Hybrid water heaters are more than 50% efficient compared to solar water heaters for half the cost.

Solar water heaters may be good for a large family who like to take long showers (most of the energy used to heater water goes to showers). The other plus side is the ever-changing APS and SRP solar hot water rebates and federal tax incentives available.  These rebates are seperate from the Home Performance With Energy Star home energy audits conducted by APS and SRP. An 80 gallon tank or two 50 gallon tanks will be installed with solar water heaters, so there will never be a shortage of hot water but can be overkill for most homes.

Some homeowners now are even switching from gas water heaters to electric because they are putting solar panels to generate their own electricity. The thought is that a big enough solar array will cover the energy needed to heat the water. Solar hot water proponents will argue that homeowners should have both – a solar water heater and a smaller solar electric system because the efficiency of the solar water heaters (1.2 efficiency factor) is greater than the efficiency of a conventional electric (0.89 efficiency factor) or gas tank. I definitely agree that efficiency steps should be done to stretch that solar electricity dollar, but the cost of a solar water heater makes other water heating options such as a tankless water heater or hybrid water heater an even smarter choice (which are all more efficient than using solar electricity).

Bottom line if you are considering solar hot water:

-  Homeowners with gas water heaters and families with children should go with a tankless water heater with a 20 gallon reserve

- Homeowners with electric water heaters should go with a hybrid water heater

- Homeowners should consider solar hot water if they are planning on living in the same house for more than 13 years. APS and SRP incentives plus federal tax credits make the investment attractive but may not be around for long.