The Basics, Advantages & Disadvantages of Integral Collector/storage Solar Water Heaters

The integral collector/storage solar water heater is quite possibly the most well known and simplest solar water heating system. It's been around a long time. Often known as the "bread box" system, it was originally produced in the 1970's but is still in use now. It is simple, efficient and cheap to build. You simply paint a tank black, put it in a big crate, insulate it all around except one side that needs to be covered by glass or plastic. All it takes is a tank, insulation and sun. The water is collected, stored and warmed all in one container.

One name brand of the integral collector/storage solar water heater you may recognize is Servamatic. The more modern version, the ProgressiveTube™, is another form of integral collector/storage solar water heaters. Yet another variation are in-line units, positioned between the well and the shower; this type of heater requires very little maintenance or repair.

This design is popular for do-it-yourself units. Not only is it simple and cheap, but it can also be made with recycled materials. They also require very little maintenance and service, which makes it popular since they are so durable.

What are some advantages to the integral collector/storage system? Low cost
No pumps or controls
Simple
Long-lasting
The large size of the tank helps to avoid freezing problems often seen in thermosiphon units

What are some disadvantages? Water doesn't get really hot
Heat loss from the collector
Certain times of optimal use of the hot water produced-making a morning shower a problem, and
Heavy.
Inefficient design

What about the manufactured integral collector/storage system?

Newer types like the ProgressiveTube™ collectors are still simple, but use 4-inch copper tubes and fins with special "selective" surfaces. More of the sun's energy is collected than regular blackened surfaces and they resist the re-radiation of this energy at night. The ProgressiveTube™ systems can be used effectively in any climate zone.

How much does a system using the ProgressiveTube™ design cost?

A new system using the ProgressiveTube™ design will cost about $2,500 in parts. There will also be labor costs. But after being used for approximately 7 years, the cost of the system will equal the cost of the electricity used to heat the same amount of water. If a homeowner is a do-it-yourselfer, then the cost is approximately $1,600.

The integral collector/storage system can be an efficient, easy-to-use and maintain solar water heating system for most any climate or home.

Sources:
Interview
US Dept of Energy
CAL Finder
DIY.com
Florida Solar Energy Center