ICS or Batch system resellers claim that their "low cost" systems are simple with no moving parts.

• Very low efficiency rates mainly due to the collector's heat escaping during the evening hours and a small collector absorber area. Most households use the majority of their hot water in the morning hours. Three or more home occupants would require two or more panels (see SRCC system ratings for your area) so the real cost is the same or more than a typical drainback system for the same performance.
• No overheating protection (except for a steam/pressure release valve) so water in your typical water heater tank can reach very high temperatures during hot summer months especially during vacation/absences. The higher temperature precipitates corrosion, scaling and sediment.
• Potable tap water moving through the attic and on roof.
• No freeze protection for areas which have even occasional hard freezes (drip valves can clog with scale and fail over time). All it takes is a couple days of sub-freezing temperatures to create a nightmare.
• No way to flush sediment buildup from the collector.
• Each panel weighs 200 to 400lbs and 450 to 700lbs when filled with water. This creates installation difficulties and puts considerable weight on the roof.

Only Hawaii and a few other locations are recommended for these systems. Misinformation and over generalizing of system performance has allowed these systems to be sold in other areas of the country. Why go through the trouble and cost of a solar installation and only get 40% to 50% efficiency (U.S.'s new tax credit is only for systems with 50% or higher efficiency)? The temperatures of the system location must be incredibly moderate (no freezing or high temperatures) with low counts of calcium or lime and moderate PH levels (click here to see the water quality in your area) in the water. But again low performance is the primary reason why these systems are not the best value... especially when one considers the many other issues listed above.

The primary disadvantages of glycol or antifreeze systems are the expense of changing the glycol every 3 to 5 years and a lack of over heating protection for the tanks. Not only does someone have to change the system's glycol every few years but the system must be re-pressurized and done properly so as to prevent air bubbles from entering the system. This is not something the average consumer is usually equipped to accomplish so a solar professional is usually called upon and the cost can range from $75 to $200 for each refill. This additional cost greatly lowers the system's financial return. The other issue involves over heating within the storage tank during the summer months. Sure the antifreeze will keep the collector loop from boiling but what about the water heater tank temperatures? As long as the collector sensor is 10-15 degrees hotter than the tank sensor the system will continue to circulate the antifreeze (it must keep circulating or the glycol will breakdown during stagnation). There is no high temperature limit control for the water heater tanks and during the summer months the tank can reach almost boiling temperatures (especially if the homeowner is gone for a few days). This greatly increases scaling, tank sediment, corrosion and additional stress on the circulating pump and other system components. The initial cost for a glycol system is the same or more than our drainback system but the added cost of periodic glycol changes and overheating headaches accrued over the system's lifespan make this system not as cost effective.

The problem with single tank systems is that one size does not fit all. The Department of Energy rightfully claims that an average American consumer uses 20 gallons of hot water daily with most of that amount being used for a hot shower.

A single tank system has an electric element usually 1/3 from the top of the tank. This is to provide the consumer with backup heat in case the solar generated heat is not enough to reach the desired temperature (around 125 degrees). If there are 3 or more system users a single tank system will not provide enough hot water during "non-solar" days. 30% of 80 gallons is only 24 gallons. 24 gallons of hot water is usually not enough for 3 or more residents in the event of a non-solar day. Some manufacturers do make a 120 gallon version but the high cost and its huge size/weight makes the unit unjustified. Synergy Solar does offer a single tank system but ONLY for a 2 person home.

Also when a single tank with a built in heat exchanger needs to be replaced (U.S. water heater tank replacement average is 9-15 years) the home owner will have to pay $800 to $1200 for a special 80+ gallon water heater.

The reason someone buys a solar water heating system is to save money and reduce pollution. The primary characteristics of choosing one system over another is as the Florida Solar Energy Center suggests; "Find a durable certified system which provides the best value for the total amount of BTUs (energy)." Vacuum tube collectors cost 25 to 40% more than flat plate collectors and outperform them only in the far northern climates (Michigan, Maine Canada and etc.) by 10 to 15% (according to United States' SRCC, Germany's ITW and Switzerland's SPF testing centers). In addition vacuum collectors are typically only utilized with glycol systems. During an average U.S. summer day a vacuum collector glycol system will reach outrageous high temperatures. This will cause premature scaling and sediment buildup, possible pump failure and tempering valve leaks. Aside from paying more dollars per BTU and dealing with high tank temperatures in the summer they do not appear as a skylight on the roof. Another issue is that even most of the better manufactured tubes can lose their vacuum after 15 years (per the best manufactures in China where most are manufactured).

Tankless or on-demand water heaters are probably one of the most over hyped products on the market. Many distributors of these units claim that the consumer will have up to 60% savings. This is a completely ridiculous statement. These types of claims prompted the government to do a thorough study to determine their realistic performance. What they found was an 8 to 20% savings pending water use (see the below cost breakdown and the actual report at (www.nrel.gov/docs/fy03osti/32922.pdf). So for a standard unit with installation ($1,000) the payback is 25+ years.

In addition to the performance issue the gas units have small copper heat exchangers. According to the manufacturers (and we couldn't agree more) if the init is placed in a scaling environment it should be periodically flushed with an acid solution. Also the electric units are actually illegal in many cities due to their extreme voltage surge. The installation cost is usually very expensive in that the electric units require very large breakers (50 amp plus) and the gas units require special venting systems.

Aside from the above issues they do take less space and provide endless hot water (3-6 gallons per minute). They can be used in conjunction with a solar system as long as the tankless system has a sensor to determine the incoming water temperature.

Most experienced professional plumbers recommend the SETS, Rennai or Takagi systems.