Residential Solar Thermal Systems NESEA BE Conference March 2011 Robb Aldrich Steven Winter Associates, Inc. firstname.lastname@example.org © 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 email@example.com Thanks to: NESEA U.S. Department of Energy Building America Program © Steven Winter Associates, Inc.
Pages to are hidden for
"Robb_Aldrich_Residential_Solar_Thermal_Systems"Please download to view full document