Solar Water Heating Basics

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Solar Water Heating Basics

• Progress Energy Florida
• Solar Water Heater Incentive Program
• Colleen Kettles
• Florida Solar Energy Research Education
  Foundation (FlaSEREF)

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Solar Water Heating Basics

• How It Works
• How Much Energy It Saves
• How It Helps the Environment
• How To Purchase
• How Much It Costs
• What Incentives Are Available

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Types of Systems

• Active System
• Direct Pumped
• Water is the collector fluid
• Freeze protection provided by drain-back tank or
  freeze valves
• Indirect Pumped
• Anti-freeze is the collector fluid
• Heat exchanger utilized within storage tank

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Active Solar Water Heater
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Active Solar Water HeaterDirect Pumped
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Active Solar Water HeaterDirect PV Pumped
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Active Solar Water HeaterIndirect Pumped
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The Collector

• Active Systems
• Use flat-plate collector
• Insulated box with ½ copper piping integrated
  into a black absorber and glass cover
• Fluid is water or anti-freeze
• Designed to reach temperatures as high as 160 F

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The Storage Tank

• Active System
• Specially designed, heavily insulated tank (R
  value of 16 or greater)
• Sizes range from 52 to 120 gallons for
  residential applications
• Has only a top electric element
• In a system using antifreeze, the tank will have
  an internal heat exchanger

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Balance of System Components

• Active System
• Pump (ac or dc)
• Differential Controller, or
• Photovoltaic Panel
• Assorted valves and vents
• Copper Piping
• Insulation

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Types of Systems

• Passive System
• Integral Collector Storage
• Collector provides additional water storage
• No moving parts

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Passive Solar Water HeaterIntegral Collector
Storage
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Passive Solar Water HeaterIntegral Collector
Storage
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The Collector

• Integral Collector Storage (ICS)
• The collector is also the storage medium
• Insulated box with 4 copper tubing welded
  together to serve as the absorber
• Glass cover
• Fluid is water
• Designed to reach temperatures as high as 160 F

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The Storage Tank

• Integral Collector Storage (ICS)
• Collector provides ½ of the storage (32-50
  gallons)
• Existing or conventional tank provides the
  balance of storage

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Balance of System Components

• ICS System
• Assorted valves and vents
• Anti-scald valve (optional)
• Copper piping
• Insulation

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Types of Systems

• Passive System
• Thermosiphon
• Tank is roof mounted above collector
• Uses flat plate collector
• No moving parts
• Reminiscent of early solar systems

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Early Thermosiphon Solar Water Heater
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Thermosiphon System
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Passive Solar Water HeaterThermosiphon System
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The Collector

• Thermosiphon System
• Uses flat-plate collector
• Insulated box with ½ copper piping integrated
  into a black absorber and glass cover
• Fluid is water or anti-freeze
• Designed to reach temperatures as high as 160 F

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The Storage Tank

• Thermosiphon System
• The storage tank is specially designed to be
  mounted on the roof above the collector
• An auxiliary tank with electric element is
  installed in the home

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Balance of System Components

• Thermosiphon System
• Assorted vents and valves
• Copper piping
• Insulation

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Household Hot Water Use

• 15 20 of total household energy consumption
• Daily usage is 20 gallons each per day for the
  first two occupants 15 gallons per day for each
  additional occupant
• Example Four person household will use 70
  gallons of hot water and will need 80 gallons of
  storage

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Collector BTU Ratings/Solar Fraction

• Central Florida ambient water temperature is 72
  degrees
• Solar fraction is the proportion of hot water
  provided by the solar system
• Optimal solar fraction is 70 and is based upon
  annual performance

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Collector Btu Ratings/Solar Fraction

• 38,000 Btus will be needed to raise 80 gallons of
  cold water to 122 degrees
• A 32 square foot ICS system is rated at 28,700
  Btu/day and will provide a 77 solar fraction
• A 40 square foot active collector is rated at
  34,400 Btu/day and will provide a 92 solar
  fraction

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Savings

• The kWh equivalent of 38,000 Btu/day is 11.13
  kWh per day x 365 days 4,063 kWh/year (electric
  load)
• A solar fraction of 70 will offset 2,844 kWh
• A solar fraction of 77 (28,700 Btu/day) 8.4
  kWh/day x 365 days, saves (or produces) 3,066
  kWh/year
• A solar fraction of 92 (34,400 Btu/day) 10
  kWh/day x 365 days, saves (or produces) 3,650
  kWh/year

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Savings

• At an average residential rate of .115 per kWh
• A solar fraction of 70 will save 325/year
• A solar fraction of 77 will save 350/year
• A solar fraction of 92 will save 420/year

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Back-up Hot Water

• All solar water heaters will have a conventional
  energy back-up
• No consumer action is required to activate the
  back-up
• Back-up is needed for periods of excessive hot
  water use or inadequate solar resource

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How It Helps the Environment

• Emission Reductions (One Solar Water Heater Saves
  Annually)
• Carbon Dioxide (5,000 lb)
• Sulfur Dioxide (20 lb)
• Nitrogen Oxide (12 lb)
• Renewable Energy Credits
• The environmental attributes of solar energy
  are a commodity

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How to Purchase

• Contact reputable solar companies
• www.flaseia.org
• www.findsolar.com
• Verify contractor licenses www.myfloridalicense.co
  m
• Voice 850-487-1395
• Solar contractor (CV)
• Specialty solar (CW)
• Plumbing contractor (CF)
• Local solar license (RX)

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How to Purchase

• Get more than one estimate, and get them in
  writing
• Avoid high pressure sales tactics
• Compare system types, sizes, prices and
  warranties
• Ask for FSEC system certification
• Ask for local references

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How to Purchase

• A local building permit should be obtained prior
  to installation (although some jurisdictions no
  longer require)
• Contractor, not the homeowner, is responsible for
  the permit
• If in doubt, homeowner should contact the local
  building department
• Deed restricted communities will typically
  require prior approval (which cannot be denied)

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How Much It Costs

• Cost of a system varies depending upon the type
  of system and the size of system
• Prices range from 3,000 to 5,000 in general
• Rising material costs and the cost of doing
  business (gasoline, insurance, etc.) have
  resulted in price increases

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Financial Incentives

• Incentives are designed to lower the cost to the
  consumer
• Sales Tax Exemption (6-7)
• Florida Solar Rebate (500)
• Progress Energy Rebate (450)
• Federal Tax Credit (30 with cap of 2,000)

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Interaction of Incentives

• Rebates should be deducted from the cost of the
  system before the federal tax credit is
  calculated
• IRS has not issued regulations under this tax
  credit law
• Exception would be if rebates are included as
  gross income

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Interaction of Incentives

• Example
• System cost 4,000
• State rebate - 500
• PEF rebate - 450
• Actual cost 3,050
• Federal tax credit (.30 x 3,050) 915
• Net system cost 2,135

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Impact of Incentives on Consumer Savings

• Net System Price of 2,135
• Annual Savings of 325 6.5 year payback
• Annual Savings of 350 6.1 year payback
• Annual Savings of 420 5 year payback

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For More Information

• www.flaseref.org
• www.flaseia.org
• www.fsec.ucf.edu
• www.floridaenergy.org
• 800-59SOLAR
• THANK YOU