These work best in areas where temperatures rarely fall below freezing. They also work well in households with significant daytime and evening hot-water needs.

(2) Thermosyphon systems

Water flows through the system when warm water rises as cooler water sinks. The collector must be installed below the storage tank so that warm water will rise into the tank. These systems are reliable, but contractors must pay careful attention to the roof design because of the heavy storage tank. They are usually more expensive than integral collector-storage passive systems.

After installation, properly maintaining your system will keep it running smoothly. Passive systems don't require much maintenance. Regular maintenance on simple systems can be as infrequent as every 3–5 years, preferably by a solar contractor. Systems with electrical components usually require a replacement part after or two after 10 years.