solar water heating basics for homeowners - go solar california
TRANSCRIPT
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Solar Water Heating Basics for Homeowners
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What is Solar Water Heating? • Solar Assist or Solar Pre-heat
• Always keep the existing heater as backup to solar
• Great way to conserve energy, reduce your utility bill, increase the value of your home, and reduce your carbon footprint!
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Source: Occidental Power
Solar Thermal Collectors
Solar Electric (PV) Panels
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Basic Components
• a) Solar Collector
• b) Sensors, Controller
• c) Pump (Active Systems)
• d) Solar Storage Tank
Source: Schuco
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1. Sun heats water or a heat transfer fluid in a solar collector
on the roof
Basic SWH Design- Step 1
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Basic SWH Design- Step 2
2. Solar heated water is pumped
into a storage tank
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Basic SWH Design- Step 3
3. Your conventional water heater draws the hot water out of
the solar storage tank when there is a
demand for hot water
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Basic SWH Design- Step 4
4. If needed, the conventional water heater may boost the temperature of the solar heated
water before sending it through
the home
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Basic SWH Design- Result
5. Using the sun to heat your
water reduces the energy
needed to heat your water
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Solar Water Heating Systems
• Collector Types • System Types
• Pros and Cons • Freeze Protection • Overheat Protection
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Glazed Flat-Plate Collector
Source: EERE Butler Sun Solutions
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Evacuated Tube Collector
Source: Apricus CleanTech
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Unglazed Collector
Source: FAFCO Son Energy
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Two Types of Basic SWH Systems
1. Passive – no pumps • Integral Storage Collector (ICS)
• Thermosyphon
2. Active – uses pumps to move the water through the collector • Direct Forced Circulation
• Closed Loop Glycol
• Closed Loop Drainback
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Passive System: Integral Collector Storage (ICS)
Source: EERE
• Passive System
(no pumps)
• Open loop
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ICS System
Source: SunEarth CPAU
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Good Application for ICS Systems
• Good for those who use hot water at night, rather than first thing in the morning
• Inefficient in cold climates, due to heat losses at night
• warmer climates are the best location for ICS system
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Passive System - Thermosyphon
Source: FSEC
Closed loop with heat exchanger &
antifreeze
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Thermosyphon Collector
Source: SunEarth CleanTech
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Thermosyphon-Pros and Cons
Advantages:
• Simple- No moving parts (Passive)
• Good for colder climates
Disadvantages:
• Higher roof load
• Glycol and heat exchanger reduce efficiency
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Active System – Direct Forced Circulation
Source: FSEC
• Open loop
• Only in climates where freezing is a rare
occasion
Freeze drain valve
DFC systems not eligible!
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Direct Forced Circulation- Pros and Cons
Advantages:
• Simple-fewer components
• Good for climates with warmer temperatures
Disadvantages:
• Freeze protection is limited to infrequent & light freezes
• Inappropriate for use with hard water- high scaling potential
DFC systems not eligible!
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Active System – Closed Loop Glycol
Source: EERE
• Glycol = Anti-freeze
• Cold Climates
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Closed Loop Glycol- Pros and Cons
Advantages:
• Basic principles well understood by conventional plumbing trades
• No problems with hard water
• Can be powered by PV
Disadvantages:
• Heat exchanger & antifreeze reduce efficiency
• Fluid may break down at high temperatures
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Active System – Closed Loop Drain back
• Cold and Hot climates
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Drain back Pros and Cons Advantages:
• No problems with hard water
• Reliable freeze and overheat protection systems
• No glycol
Disadvantages:
• Heat exchanger reduces efficiency
• Collectors & piping must have adequate slope to drain
• Requires larger pump to lift water on startup
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Source: SunTrek Solar
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NEW CSI-Thermal Program
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2007-2009 Project Cost Data for Single Family SWH
Type of System
Integral Storage
Collector
Direct Forced
Circulation
Thermo-syphon
Closed Loop
Glycol
Closed Loop
Drain back
Overall Average
Number Installed
12 34 74 125 61 Total= 306
Average Cost
$5,529 $6,207 $6,680 $6,989 $6,868 $6,746
Average Incentive
$924 $1,408 $1,180 $1,325 $1,211 $1,260
As of April 2010
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CSI-Thermal Program Background
• $350M Incentive Program (2010-2018)
• Senate Bill (SB) 1, 2006: Authorized $100.8M of incentives for solar thermal technologies that displaced electricity usage
• Assembly Bill (AB) 1470, 2007: Authorized $250M for the installation of 200,000 SWH systems that displace natural gas
• SWH Pilot Program created to test market from July 2007- Dec 2009
• CSI-Thermal Program approved by CPUC in January 2010
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CSI-Thermal Implementation Timeline
• May 1, 2010: Started accepting residential applications
• October, 2010: Start accepting multi-family/commercial applications
• Any project installed or received a building permit after July 15, 2009 may apply
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CSI-Thermal: Customer Eligibility • Gas water heating customers of PG&E, SDG&E, or SoCal
Gas- Retrofit and new construction
• Electric water heating customers of PG&E, SDG&E, or SoCal Edison- Retrofit projects only
• Propane users are NOT eligible, even if they are electric customers of the above utilities
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CSI-Thermal: Technology Eligibility
Eligible:
• Domestic Solar Water Heating Systems
Not Eligible:
• Pools and Spas
May be added to the program at a later date:
• Non-DWH gas displacing solar thermal technology (space heating and cooling)
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Incentives
• Calculated based on expected performance, using expected annual energy savings (SRCC rating), surface orientation factor, and shading analysis
• 4 step declining incentive structure
• Different incentive amounts for natural gas vs. electric displacing systems
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Incentives: Natural Gas
Steps $ per therm saved
Single Family Cap
Step 1 $12.82 $1, 875
Step 2 $10.26 $1,500
Step 3 $7.69 $1,125
Step 4 $4.70 $688
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Example: OG-300 Incentive Formula (Natural Gas)
1. Annual Energy Savings =120 therms
2. Step 1= $12.82/per therm saved
3. Surface Orientation Factor= 1.0
4. Shade Factor= 98% solar availability
Calculation:
125 therms x $12.82 x 1.0 X .98 = $1508
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Natural Gas Water Heating Costs • Average home with a natural gas water heater
uses 200 therms per year for water heating
• SDG&E charges roughly $1.25/therm
• 200 x $1.25 = $250/year for water heating
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SWH Savings with a Natural Gas Water Heater • Average SWH system in San Diego installed
with a natural gas water heater saves 120 therms/year
• 120 x $1.25 = $150/year saved on water heating
• Annual water heating bill is reduced from $250 down to $100! ($250-$150=$100)
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Incentives: Electric
Steps $ per kWh saved
Single Family Cap
Step 1 $0.37 $1262
Step 2 $0.30 $1025
Step 3 $0.22 $750
Step 4 $0.14 $475
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Example: OG-300 Incentive Formula (Electric)
1. Annual Energy Savings =2780 kWh
2. Step 1= $0.37/per kWh saved
3. Surface Orientation Factor= 1.0
4. Shade Factor= 98% solar availability
Calculation:
2780 kWh x $0.37 x 1.0 X .98 = $1008
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Electric Water Heating Costs
• Average home with electric water heater uses 4,000 kWh per year for water heating
• SDG&E charges roughly $0.20/kWh
• 4,000 x $0.20= $800/year for water heating
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SWH Savings with an Electric Water Heater • Average SWH system in San Diego installed with an
electric water heater saves 2,800 kWhs/year
• 2,800 x $0.20 = $560/year saved on water heating
• Annual water heating bill is reduced from $800 down to $240! ($800-$560=$240)
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Additional Incentives
• Federal Tax Credit – 30% of cost (post-incentive)
• Increased property value but exempt from increase property tax
• Protection against future rate increases
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SWH Financials
Average Cost • Based on 3-4 person
household
CSI – Thermal Incentive • $12.82/therm (average
therms saved/year =125)
Federal Tax Credit • 30% of out of pocket costs
Average Cost • $6700
Average rebate (natural gas system)
• $1500
$5200 x 30% = $1560
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Environmental Economics of SWH • NG offset –
• Electric offset –
• Equivalents • 2004 Toyota Corolla driven 12,000 miles/yr
• 8,095 lbs. CO2/year
• NG offset = no driving for 4.7 years • Electric offset = no driving for 3.3 years
• Trees • Absorb 2,000 lbs. CO2/year
• NG offset = planting 19 trees • Electric offset = planting over 13 trees
Lbs. CO2 Saved 38,089
Lbs. CO2 Saved 26,992
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What to expect from program participation Quality Control:
• Contractors must come to a one day training to participate
• Projects must be permitted (contractor will obtain)
• Projects may be inspected by us
• Projects may be selected for performance metering
Customer Service:
• Call us anytime with questions
• Unbiased, objective support
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How to select a SWH Contractor
• Select from the eligible contractor’s list: http://www.gosolarcalifornia.org/solarwater
• Ask about the contract structure- who gets the rebate?
• Get at least 3 bids
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Contract Structure Options
Scenario: Total cost=$6,700; Incentive=$1,500
Option 1: You pay $5,200 to contractor; $1,500 incentive goes to contractor after project completion
Option 2: You pay $6,700 to contractor; $1,500 incentive goes to you after project completion
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California Energy Commission (CEC) Cash for Appliances Program
• Single family homes only: $750 flat rebate
• SWH system must be Energy Star
• Must replace & recycle an old water heater
www.energy.ca.gov/recovery/energystar.html