Robb_Aldrich_Residential_Solar_Thermal_Systems by gstec

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									Residential Solar Thermal Systems




                            NESEA BE Conference
                                March 2011
                                            Robb Aldrich
                                   Steven Winter Associates, Inc.
                                       raldrich@swinter.com
© Steven Winter Associates, Inc.
                         AIA CEUs

NESEA is a registered provider with the American Institute of Architects
Continuing Education Systems. Credit earned on completion of this
program will be reported to CES Records for AIA members. Certificates
of Completion for non-AIA members will be mailed at the completion of
the conference.

This program is registered with the AIA/CES for continuing professional
education. As such, it does not include content that may be deemed or
construed to be an approval or endorsement by the AIA of any material
of construction or any method or manner of handling, using, distributing,
or dealing in any material or product. Questions related to specific
materials, methods, and services will be addressed at the conclusion of
this presentation.
             Objectives

Basics of solar DHW for cold climates:
• What kind of equipment?
• How do the systems work?
• How much energy do they collect?
Icing on the Cake
         Collectors

Flat Plate     Evacuated Tube
     Flat Plate Designs

Two major Flat-Plate types:




   Parallel            Serpentine
Manifold (Harp)
Flat Plate Collectors
Flat Plate Collectors
Evacuated Tubes
                       Collectors

          Flat Plate                     Evacuated Tube




             Pro’s                             Pro’s
• Lower cost (often)             • Higher temperature
                                 • Better generation in low temps
            Con’s                  and low light*
• Heavy
• Less output in low temps and                 Con’s
  low light*                     • Higher temperature (summer)
                                 • Higher cost (sometimes)
                                 • Snow shedding
Evacuated Tubes and Snow
       Flat Plate vs. Evacuated Tube

                                   Flat Plate vs. Evacuated Tube Efficiency
                                         68°F Ambient Temperature, Clear Day

                       100%
                       90%
                                                                       Flat-Plate
                       80%
Collector Efficiency




                                                                       Evacuated Tube
                       70%
                       60%
                       50%
                       40%
                       30%
                       20%
                       10%
                        0%
                              50    75       100       125      150      175        200   225
                                              Fluid Temperature [Ti, °F]
                 Heat Storage

• Water tanks
• Typically 1.5 – 2 gal/ft2 of
  solar collector area
• Insulate tanks well (e.g.
  added tank wraps)
• Locate tanks close to
  collectors AND auxiliary
  heaters
ICS: Direct, Warm-Climate
         System
ICS
Freeze-Protection Strategies

Two Main Strategies:
• Drainback
• Closed-loop with antifreeze
   Drainback
                      AV




                                  MIXING VALVE
                                   PREVENTS
                                   SCALDIING


      COLD WATER IN                              HOT WATER
                                                 TO LOADS




 DRAINBACK
STORAGE TANK               AUXILIARY
                   Drainback Control
                                                AV
               T




                                                            MIXING VALVE
                                                             PREVENTS
                                                             SCALDIING


                                COLD WATER IN                              HOT WATER
Differential                                                               TO LOADS
 Control




                      T


                           DRAINBACK
                          STORAGE TANK               AUXILIARY
Closed Loop, Antifreeze
Freeze-Protection Strategies


      Drainback                          Antifreeze

             Pro’s                              Pro’s
• Possibly lower maintenance     • Versatile plumbing runs
  (no replacing antifreeze)      • Smaller pumps (PV-powered
 • Good overheating protection     possible)
                                 • Serpentine or parallel manifold
                                   collectors
             Con’s
• Larger circulators                          Con’s
• Plumbing slopes critical       • Glycol must be maintained
• No serpentine collectors       • High temperature protection
                                   needed
Solar Thermal Certifications




http://www.solar-rating.org/
SRCC OGC-100, collector certification

SRCC OGC-300, system certification
Section 6: Certification Criteria
  Monitored Systems

Hadley, MA   • Two, 32-ft2 flat-
               plate collectors
             • Closed-loop, 50%
               propylene glycol
             • 80-gallon storage
               tank
             • Separate auxiliary
               heater
Mass. System Schematic
      Massachusetts Performance

                                       Domestic Hot Water Energy
                                           Massachusetts
                 50

                 40
Average Energy
  [MBtu/day]




                 30

                 20
                                                  Auxiliary DHW Energy
                                                  [MBtu/day]
                 10                               Solar Preheating Energy
                                                  [MBtu/day]

                  0
                                                  A-05




                                                                              A-05
                                                                                     S-05
                                                                                            O-05




                                                                                                                                      A-06
                      D-04
                             J-05


                                           M-05


                                                         M-05
                                                                J-05
                                                                       J-05




                                                                                                   N-05
                                                                                                          D-05
                                                                                                                 J-06
                                    F-05




                                                                                                                        F-06
                                                                                                                               M-06
                                                                        Month
     Performance




            Overall
Hot Water Use: 64 gal/day

Annual Solar Fraction: 61%
        Monitored Systems

• Two, 32-ft2 flat-
  plate collectors
                       Madison, WI
• Closed-loop, 50%
  propylene glycol
• 80-gallon storage
  tank
• Separate auxiliary
  heater
Tankless WH Integration
                  Wisconsin Performance

                                    Domestic Hot Water Energy
                                           Wisconsin
                 50

                 45

                 40
Average Energy
  [MBTU/day]




                 35

                 30

                 25

                 20                                Auxiliary DHW Energy
                                                   [MBTU/day]
                 15
                                                   Solar Preheating Energy
                 10                                [MBTU/day]
                  5

                  0
                             A-05




                                            J-05

                                                       J-05

                                                               A-05

                                                                          S-05

                                                                                 O-05




                                                                                                      J-06
                                                                                        N-05

                                                                                               D-05
                      M-05




                                     M-05




                                                              Month
      Performance



           Overall
Hot Water Use: 71 gal/day

Annual Solar Fraction: 63%
RDI Home – Colrain, MA
        Monthly Heat & HW Energy [kBtu]




                 0
                     1000
                            2000
                                   3000
                                             4000
                                                            5000
        Jun-07
        Aug-07
        Oct-07
        Dec-07
        Feb-08
        Apr-08
        Jun-08
                                          Solar




        Aug-08
                                                  Propane




        Oct-08
        Dec-08




Month
        Feb-09
        Apr-09
                                                                         RDI Colrain Home:




        Jun-09
        Aug-09
        Oct-09
                                                                   Space and Water Heating Energy




        Dec-09
        Feb-10
        Apr-10
                                                                                                    RDI Home – Colrain, MA




        Jun-10
         Solar DHW: Cost


Typical cost of solar DHW system on
         single-family homes:
          $9,000 - $15,000
Generally:
• Cost-effective with expensive water
  heating (e.g. elec. resistance)
• Not cost-effective with very efficient water
  heaters (e.g. gas tankless, eff. indirect)
SDHW Recommended Spec’s

For SF Homes:
• Work with contractors
• Comply with SRCC OG-300 Chapter 6 requirements
  (not necessarily OG-300 certified)
• Approx. 60-80ft2 of flat-plate collector
  (or maybe less evacuated tube)
• Approx. 80-120 gallons storage
• Pipe runs minimized; insulate pipes to at LEAST R-4
  (more recommended)
• High temperature protection (heat dumps or other for
  glycol systems)
• Clear manual for operation and maintenance
• Commission the system!
                                   Thank You!


            Robb Aldrich
            Steven Winter Associates, Inc.
            50 Washington St.
            Norwalk, CT 06854
            203-803-5097
            raldrich@swinter.com

            Thanks to:

            NESEA

            U.S. Department of Energy
            Building America Program


© Steven Winter Associates, Inc.

								
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