Here Comes The Sun Applications of Solar Energy. Marc Rosenbaum, P.E. South Mountain Company West Tisbury, MA

Transcription

1 Here Comes The Sun Applications of Solar Energy Marc Rosenbaum, P.E. South Mountain Company West Tisbury, MA

2 Learning objectives 1 Participants will learn how to quantify the amount of sun reaching a surface 2 Participants will learn how these energy flows compare with the loads of advanced buildings 3 Participants will learn how to apply the sun s energy to serve building loads 4 Participants will have fun

3 Agenda 1 Solar gain calculations with PVWatts 2 Solar gain calculations with AVOTS 3 Daylight factor calculations 4 Case study

4 How much energy is in sunshine? Introducing PVWatts

5 PVWatts

6 PVWatts Output

7 Back to PVWatts Pick the State

8 PV Watts Pick the City

9 PV Watts Input Page

10 PV Watts Input Page

11 PVWatts

12 Solar insolation by orientation 45,000 40,000 35,000 30,000 BTU/ft2/month 25,000 20,000 South vertical East vertical North vertical West vertical 15,000 10,000 5,000 - Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

13 Solar insolation by orientation 70,000 60,000 50,000 BTU/ft2/month 40,000 30,000 South 42 degree pitch Horizontal South vertical East vertical North vertical West vertical 20,000 10,000 - Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov

14 Calculate Monthly Solar Gain Insolation x 317 x days/month = BTU/ft2/month

15 Calculate Window Solar Gain BTU/ft2/month x ft2 x SHGC x 0.85 x % unshaded = BTU/month

16 Compare to Heating Load

17 Solar Hot Water

18 Compare to DHW Load BTU/ft2/month x ft2 x efficiency = BTU/month

19 Solar Electricity

20 Solar Electricity kwh/kw

21 Solar Electricity

22 Clear Day Hourly Introducing AVOTS pec/toolbox/arch/calculators.shtml

23 Clear Day Hourly

24 Clear Day Solar Gain

25 Daylighting with Toplighting

26 Daylighting with Toplighting Simple Calculation of Effective Aperture for overcast period daylighting from above Inputs: - Skylighting aperture (skylight area/skylit floor area) - Glazing visible light transmission (VLT) - Well factor (WF) - Dirt/screen factor of 0.85 Effective aperture = Skylighting aperture x VLT x WF x 0.85

27 Well Factor How much light that enters a skylight well gets into the space below First calculate Well Cavity Ratio (WCR): WCR = 5 x H x (W + L) / (W x L) Say a skylight is 4 x 4 and the well is 3 deep - WCR = 7.5

28 Daylighting with Toplighting A WCR of 7.5 with a reflectance of 0.80 has a Well Factor of 0.68

29 Case Study West Tisbury Project South Mountain Company Photos Derrill Bazzy

30 Case Study West Tisbury Project 3,000 ft2 multipurpose building gallery, shop, greenhouse, solar electricity Not heated, but high quality thermal envelope and very tight construction Solar applications include solar electricity, solar greenhouse with remote thermal storage, daylighting

31 Solar Electricity Estate usage of 36,000 kwh/year and objective of net zero electricity Buildings are heated with propane; swimming pool converted from propane to a heat pump Objective of providing power when the grid is down led to a bi-modal system with SMA grid-tied and offgrid inverters with battery banks 35 kw of Sunpower panels mounted on the standing seam roof expected annual output of ~ 45,000 kwh

32 Solar Electricity

33 Solar Thermal Solar greenhouse designed to keep plants at 50F or more through the winter without heating Glazing is double low-e argon Cardinal 180 When greenhouse temperature is greater than thermal storage temperature a blower turns on to transport heated air from the greenhouse to the basement level thermal storage Heat retrieval during cold night time conditions is via passive natural convection

34 Solar Thermal Clear day calculations on vertical and horizontal glazing to assess thermal storage need final design has 300 five gallon water containers that store 125,000 BTU over a 10 F rise concrete in the basement adds significant additional storage Peak hourly net gain calculation to size the blower

35 Solar Thermal

36 Solar Thermal

37 Solar Thermal

38 Solar Thermal

39 Daylighting Both gallery and shop were designed with little sidewall glazing Toplighting via a continuous ridge skylight was chosen to daylight these spaces A Daylight Factor of 2% was the target Glazing is triple low-e argon Cardinal 272 VLT is 56%

40 Daylighting

41 Daylighting

42 Daylighting

43 Daylighting

44 Daylighting

45 Thank you