Viessmann. The Vitosol 200-T vacuum-tube system for residential or commercial installations offers versatility for horizontal or vertical mounting options in roof, wall, or freestanding installations. Direct-flow solar collectors have sol-titanium-coated copper absorbers, thick borosilicate tubes, and permanently vacuum-sealed glass-metal joints. Plug-in connectors allow for tube rotation up to 25 degrees to optimize collector placement on most sites. Up to 150 tubes can be connected in series. It includes the SRCC label. 800.288.0667.