Active system solar water heaters s and Passive systems solar water heaters

There are two basic types of Solar Water Heaters:  Passive Solar Water Heaters (for warm climates) & Active Solar Water Heaters (for moderate and cold climates).  Active systems utilize a circulating pump and some type of temperature control. Passive systems do not have any moving parts and rely on the basic principle of physics - that hot water rises & cold water falls.

Active systems solar water heaters use electric pumps, valves, and controllers to circulate water or other heat-transfer fluids through the collectors. They are more expensive than passive systems and are only slightly more efficient. Because they use electricity, they will not function in a power outage.

Passive systems solar water heaters move household water or a heat-transfer fluid through the system without pumps. Passive systems solar water heaters have no moving parts and no electric components to break. This makes them generally more reliable, easier to maintain, and longer lasting than active systems. Passive systems are less expensive than active systems and will function during power outage.

Flat Plate Solar Collector with Evacuated-Tube Collectors is the best choice for the real cold parts of the country. It provides up to 100% of water heating needs and 50% to 60% of space heating needs in the area shown on the map above. It may also be a good choice in Moderate climates where space heating needs may be significant.

The Passive systems solar water heaters is the most cost efficient water heater and it works well in the entire area shown above. This system should be the only logical choice for the southern states as it provides 80-90% of solar water heating needs in the darker area shown above, 60 to 70% in moderate climate areas and 50% in the northern colder states. A Passive System can only be subject to freezing in the areas where hard freeze months exist, and drainage would be used to protect it during these periods.