Solar Panels for a Rehab Project

An alternative to solar panels for hot water in our northern climate may be solar vacuum tubes. These panels of  tubes are manufactured in Great Britain, China and other countries* andhave been used in Great Britain with success for many years where the sunlight is limited due to cloud cover.                

Last year we looked into going solar with a rehab project but actually had difficulty getting the installer to come and evaluate the site as he was very busy.  We let the idea slide as we were very busy and now we are considering the solar vacuum tubes which appear to be less costly and more suited for the northern latitudes. 

Has anyone had any experience with solar vacuum tubes?

*The few companies listed as U.S.manufacturers have distribution centers and a few may have R & D sites in the USA, but I could not find any manufacturers that built solar vacuum tubes in our country.