There are two types of large commercial solar tanks pressurized and non-pressurized. Because the pressurized tank need to handle high pressure from a domestic water system its construction must be much different and as such uses much heavier material and as a result cost more.

Pressurized Solar Tanks
Pressurized Solar Tanks

A pressurized commercial tank is constructed similar to a residential solar water tank but has a larger volume. As such they cost more to manufacture and more to ship. Most tanks have internal heat exchangers but sometimes a pressurized tank will utilize an external heat exchanger and a pump to circulate the tank water through the heat exchanger. This save in cost as internal heat exchangers are expensive and maintenance means replacing the whole tank. A good commercial tank also needs to have good insulation value to be effective and this can add to the manufacturing cost.

Certification of a pressurized tank is a must as it could possibly explode under improper use. As such a pressurized tank must have a NSF/ANSI certification number. Because of the relative low production volume it is costly for a manufacture to obtain this certification which adds to the cost.

Multiple pressurized tanks can be used as a cost savings alternative by daisy chaining the tanks together to form a large volume. This has its advantages as the availability of tank under 120 gallons are plentiful and the costs are relatively affordable. It is certainly less expensive to use 2 x 120 gallon tanks than purchase a 240 gallon single tank.

Multiple tank connections for a large storage volume

The diameter of the tank also plays an important role in selecting the size. As the tank gets larger so does its size. Moving the tank to an interior location may be challenging if not impossible. Tanks with a diameter greater than 36" will not fit through a normal size commercial door and the contractor will need to consider this when sizing a tank. Tall narrow tanks sizes are available but then ceiling height needs to be addressed.

Shipping costs - When installing a commercial heating project you may want to source a tank locally. Shipping large commercial tanks can be very expensive and may eat up the budget. When shopping for large commercial tanks you may have no alternative but to have one shipped in as certified pressure tanks are not commonly sold in every city. This is where the daisy chain tank solution becomes a great alternative.

Non Pressurized Tanks

A non-pressurized tank is a much more cost effective solution for most commercial solar heating systems. Because there is no pressure a non-pressurized tank only needs to be constructed to hold the weight of the water. This means a much cheaper means of construction.
A non-pressurized tank is typically built on site and comes as a knock down DIY kit. This greatly decreases the transportation cost and also allow the tank to fit through most commercial doors.

The insulation value of a non-pressurized tank is important and should be considered when choosing a tank. Our non pressurized commercial tanks come in insulation values allowing a heat loss of less than 2 degrees per day.

A non pressurized tank is not suitable for direct potable water consumption. The water in the tank is only used as an energy store and this energy is moved into and out of the tank via pumps and heat exchangers. If the project requires potable water then this can still be done effectively with a non-pressurized tank by using an appropriately sized external heat exchanger or a 2nd water tank with an internal heat exchanger.

STSS Large Commercial Solar Tank

STSS Large Commercial Solar Tank

These are great tanks for commercial applications as they are cost effective and extremely energy efficient. These tanks come in sizes for 120 gallons to 5000 gallons, and because most of the construction is insulation, they can be shipped at 1/10 the cost of a large steel tank. Available with multiple copper heat exchanger arrangements. The modular design allows these tanks to be easily assembled on site, and are only 19” wide by 53” tall when shipped (length varies).