Monthly values of thermal and electrical measurements in the system described above and the results of a simulation for the period from September 2003 to February 2004 are presented in Table 1. From November 2003, thermal energy for space heating is obtained from a gas heater. But thermal energy for domestic hot water preparation is only partly covered with the gas heater. Diagram in Figure 5 shows monthly values of the fractions in thermal energy supply. It is obvious that the excess of thermal energy produced in solar collectors in September covers the shortage of thermal energy in October. In this case the additional heating from the gas heater is not required. Figure 6 shows the comparison between the simulation and measurements in the pilot project "Solar roof Spansko — Zagreb”.

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