How to clean evacuated tube solar water heater tubes

Note: This is a delicate process that risks damage to the tubes or a leaking water if not done with care.

This is a general guide of how to clean the solar tubes.

Always consult the installation and maintenance guide for your solar water heater model on exact steps for your particular model or consult a certified technician to maintain the heater’s warranty.


Evacuated tubes can get quite hot. Cleaning the tubes should only be attempted early morning or late in the evening when they are cool.
What you will be cleaning

Cleaning the tubes includes cleaning the outside of the tubes to remove any dust or other soiling that may have covered the tubes affecting their ability to heat water.
Cleaning the inside of the tubes to remove any scale that affects the tubes heating efficiency.

What you need

Soapy water – clean plain water with soap
White vinegar solution
White cloth to cover the tubes after cleaning
Water hose pipe to flush water into the tubes
Evacuated tube collectors should be cleaned about every two years or so depending on the quality of water supply or environment. Solar water heaters in dusty environments for example require more frequent cleaning.

How to clean

Close the inlet valve supplying the water heater with water
Follow your manual on actual steps to remove each of the tubes at a time.
Wipe each tubes exterior with a soft cloth dipped in the soapy solution to remove any dust, pollen or other soiling.
Rise each tube’s exterior to remove the soapy solution.
Gently shake each tube while holding it vertically to loosen any scale that may have built up.
Flush the interior of each tube first with vinegar to dissolve any scale scale.
Next, flush the interior of each tube using a hose pipe to remove any remaining scale.
Place flushed and clean tube in a safe place without risk of breakage. Cover with the white cloth to prevent it from heating up while it is empty
Repeat steps 2 to 6 for each tube.

Fit each of the tubes back carefully and snugly to avoid leaks (follow your heater model instructions).
Do this while it is cool so that the tubes do not heat up while they are still empty.
After fitting all the tubes, cover them with a white cloth and open the water inlet valve to allow water into the heater.
When the tubes are filled with water, remove the white cloth so that they can receive the sunlight to begin heating the water.
In summary, cleaning of your solar water heater should be done when the panels or tubes are cool to avoid damage from expansion. Cleaning of both the panels and tubes exterior can be done using a soft cloth soaked in a soapy solution to remove any soiling.