1. PV in glazed facades Thermal indoor climate Søren Østergaard Jensen Industry and Energy Teknologisk Institut

2. PV in glazed facades

3. First some theory 2 and 3 D heat losses directly transmitted solar radiation absorption convection long wave radiation infiltration conduction reflection

4. Simple theory heat loss – U-value [W/m 2 K] directly transmitted light and solar energy indirectly transmitted solar energy absorbed solar energy reflected solar energy solar radiation

5. n transmittance for light – τ-value n incoming solar energy – g-value n heat loss – U-value Parameters in the simple theory

6. n PV-cells have impact on the g-value n PV-cells haven’t impact on the U-value n the U-value has impact on the g-value Parameters in the simple theory

7. n 1 pane of clear glass 0.85 n 2 panes of clear glass 0.75 n 3 panes of clear glass 0.65 n 2 panes clear glass with low-e coating 0.60-0.65 n Windows with solar screening 0.25-0.50 Examples of g-values g-value

9. n The PV cells are mounted in the external pane of a low-e n window with Argon between the two glass n Product opening g-value light trans- n area mittance n Würth WSS0007 8% 0.13 0.06 n Würth WSS0008 21% 0.19 0.15 n Würth WSS0009 22% 0.20 0.16 n MSK / Suntech MST-44T101OU10% 0.13 0.07 n MSK / Suntech MST-50T051OU 4% 0.11 0.04 n Interpane – reference panel31% 0.23 0.22 n U-value: 1.2 W/m 2 K Windows with PV-cells

10. n The PV cells are mounted in the external pane of a traditional n window with air between the two glass n Product opening g-value light trans- n area mittance n Würth WSS0007 8% 0.23 0.07 n Würth WSS0008 21% 0.30 0.16 n Würth WSS0009 22% 0.30 0.17 n MSK / Suntech MST-44T101OU10% 0.23 0.07 n MSK / Suntech MST-50T051OU 4% 0.20 0.04 n Interpane – reference panel31% 0.34 0.23 n U-value: 2.8 W/m 2 K Windows with PV-cells

11. Example: small office building Heated floor area: 650 m 2 Window area: 31 % of heated floor area

14. Cold down fall

15. U-value Window: 1,5 W/m²K Wall: 0,2-0,4 W/m²K ”Cold down fall”

16. Solar shading

18. g-value Nu 0.17 Suncool 0.32 Float 0.65

19. PowerShades