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Solar Glazing and Panels
Sun-Lite® Glazing Material
Sun-Lite® Prefab Glazing Panels

Solar Storage
Thermal Storage Tubes




Question: Is your greenhouse or sunspace too hot during the day and too cold at night?

Answer: Add thermal mass with Sun-lite® Thermal Storage Tubes.

Water contained in low cost, non-pressurized cylinders has proven to be the most practical and effective approach to the capture and storage of thermal energy for space and hot water heating.  Water stores 3 to 4 times as many BTU's per lb. as rock or masonry.  It also releases this heat energy faster when you really need it. With over 35,000 units in use worldwide, Sun-Lite® Solar Storage Tubes are the most efficient and cost effective way to store solar thermal energy and keep your greenhouse or sunspace cooler in the summer and warmer in the winter.

How do they work?

Sun-lite® Thermal Storage Tubes work by absorbing the excess heat energy generated in your greenhouse or sunpace during the day and releasing it at night to effectively control the large temperature swings between day and night.  Think of them as heat sinks.  The cooler you can keep your greenhouse or sunpace during the day the less heat you lose through your glazing or window areas.  The stored heat in the tubes through simple thermo-dynamics will automatically release itself into the space when the air temperature drops below the water temperature in the tubes.  No moving parts. 

How many do I need?

The general rule of thumb is 2 to 3 gallons of water per each sq. ft. of south facing glazing. An example is if your greenhouse has a south facing wall that is 12' long x 8' high you would need somewhere between 192 to 288 gallons of water.  In this example four to six 12" diameter x 8' tall tubes would work, or you could use any combination of the sizes that we offer.  See specification chart at the bottom of the page.  We can also make custom heights to fit your needs. 

Salt Lake City Residence Discovers the Advantages of the Solar Storage Tube

 Proven, Low Cost Solution
  • Low cost containers designed to be the most economical per gallon of storage;
  • Containers transmit natural daylight;
  • Wide selection of diameters and heights available to compliment any design;
  • Corrosion free fiberglass construction;
  • Faster usable B.T.U. gain in 60% less space and 80% less weight than with rock or masonry;
  • Self supporting containers require only flat, level floor;
  • Easy to install or remove; largest tubes weigh less than 20 lbs. empty!

The Solar Storage Tubes can be used in residential, commercial, industrial, and agricultural applications. Designs based on the following concepts have been proven to provide up to 100% of space heating and hot water needs depending upon climate and site conditions.

Direct Gain Clerestory

Direct Gain Water Wall

Installed adjacent to a solar window, the tubes absorb solar energy, store the energy, and transmit natural daylight. The tubes temper both the heat and light from the sun by removing the wide temperature fluctuations common to other direct gain systems, and by reducing glare from the solar window to workable levels.

The tubes may be filled with dyed water to increase absorption efficiency and to provide design versatility.

Direct Gain Vertical Wall

Controllable Passive

A direct gain design can be modified to separate the Solar Storage Tubes from the adjacent heated space to provide more control over heat gain. movable or fixed, opaque or light transmitting partitions are employed, depending upon design requirements. Heat built up in storage is extracted by natural convection
and/or a low power fan

Wall application: Solar Storage Tubes are positioned adjacent to a multi-layered solar window with high solar transmision and good insulation such as our Sun-Lite Glazing Panels. In very cold climates, movable insulation should be considered, analyzing the trade offs between additional costs and B.T.U.'s saved.

Direct Gain Sloped Wall

The Solar Storage Tubes are normally filled with black dye in this configuration and placed vertically. Air for heat extraction flows either horizontally or vertically over the tubes. A wall application provides natural shading in the summer to reduce overheating.

Controllable Passive Wall


Diameter Height Volume Weight Heat Capacity Floor Loading Lbs. Floor Loading Lbs.
(inches) (feet) (gallon) (full) (20° Rise (BTU) Per Lin. Ft. Per. Sq. Ft.
12 4 23.5 204 3,900 204 260
18 5 66 567 11,000 378 321


Solar Storage Tubes

Diameters vary slightly for nesting during shipping



12" X 4'_________





18" X 5'_________


Friction Fit Covers

12"______________ #11100_______
18"______________ #11110_______