Investigations of four different evacuated tubular solar collectors produced by different Chinese manufacturers have been carried out. Tests of a small solar heating system for domestic hot water supply with the four different collectors have been carried out. By means of the tests the efficiency of the collectors have been determined. The incidence angle modifier have also been determined by means of the tests. The yearly thermal performance of different solar heating systems have been calculated both with the Chinese evacuated tubular solar collectors and with normal flat plate collectors for Danish conditions. By means of the investigations the suitability of the evacuated tubular solar collectors are evaluated.