There are collectors consisting of vacuum tubes made of very thin (1.4-2mm) borosilicate glass. Virtually all factories producing vacuum tubes are located in China, where this type of solar collectors are the most common. Their impact resistance is insufficient for the Latvian climate, where there are regular storms that break branches and lift various objects into the air. Hail grains in Latvia also tend to reach dangerous sizes for vacuum tubes.
Tubular solar collectors are not certified by any reputable testing laboratory in Europe because they cannot withstand the stringent impact resistance requirements. In winter, the temperature in Latvia is often around 0o C. As the snow melts, it gets between the pipes of the solar collector, but when the frost returns, the ice can break from the pipe made of thin (1.4-2 mm) glass. The design of tubular solar collectors rarely fits into the architecture of buildings. In addition, they are less effective in summer, when the sun's intensity is highest.