Solar water heater shock absorbers are evacuated plugs. They can convert solar energy into heat for heating water. Evacuated plugs have been used for many years in Germany, Canada, China, and the UK. Several types of evacuated plugs are available for the solar industry. Solar collectors use the most common "twin-glass plug." Due to its reliability, good performance, and low production cost, the plugs are made of extremely strong borosilicate glass. The outer plug is transparent, allowing light to pass through and minimizing reflection. The inner tube is coated with a layer of a special selective coating (Al-N/Al) with excellent solar radiation absorption and minimal reflection, significantly improving the efficiency of solar energy absorption. The top of the two tubes is fused together, forcing excess air into the space between the two layers of glass by exposing the tube to high temperatures. This "emptying" of the glass creates a vacuum, which is an important characteristic for good