Solar hot water heaters | Alternative Energy | Forums

Solar hot water has interested me for awhile. I don't have gas, propane or oil. My entire house is completely ran by electricity. We have taken other measures to make our home more energy efficient. That will be for another thread.

We have a 40 gallon electric hot water heater. It has dual elements and is feed from a 30 amp breaker. 240volts x 30 amps = 7,200 watts (I know the heater uses less amps than the breaker size but I can't see the run load amps because I insulated the tank)

I have been researching different ways to use my existing hot water heater as my only tank and keeping the heating elements as back up water heating.

The best option I have found is from this company.

http://www.heliatos.com/

The type of systems this company sells work best in warmer climates and in places where freezing is very uncommon (1 or 2 days a year). don't wanna burst those water coils.

There are options for areas that can freeze. Some better than others.

Most systems that people have that are in freezing areas don't pump water to the roof, they use glycol (antifreeze) that pump to the roof to get heated, then back down to a special tank that has a inner coil loop that the antifreeze travels through that heats the water in the tank. This type of system is expensive.

The simplest system is a batch (thermo-syphon).

This system works by having a tank outside that absorbs heat from the sun and as the water temp rises, the hottest water naturally rises up back into the house and into your water heater. The coolest water in your tank will naturally travel down to the tank outside. Creating a natural loop with no pumps. Your indoor tank need to be at least 3 foot higher than the outdoor tank thats heated by the sun to create this loop.

CAUTION!

SOLAR HOT WATER CAN GET VERY HOT ALMOST BOILING! The use of mixing valves and anti scald valves will need to be added to almost any system.

I plan to update this thread with more links and photo of systems and more info about freezing and safety features.