Solar Water Heating Basics

Progress Energy FloridaSolar Water Heater Incentive

ProgramColleen Kettles

Florida Solar Energy Research & Education Foundation (FlaSEREF)

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

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

Active Solar Water Heater

Active Solar Water HeaterDirect Pumped

Active Solar Water HeaterDirect PV Pumped

Active Solar Water HeaterIndirect Pumped

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

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

Balance of System Components

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

Types of Systems

“Passive” System Integral Collector Storage

Collector provides additional water storage

No moving parts

Passive Solar Water HeaterIntegral Collector Storage

Passive Solar Water HeaterIntegral Collector Storage

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

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

Balance of System Components

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

Types of Systems

“Passive System” Thermosiphon

Tank is roof mounted above collector

Uses flat plate collector No moving parts Reminiscent of early solar

systems

Early Thermosiphon Solar Water Heater

Thermosiphon System

Passive Solar Water HeaterThermosiphon System

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

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

Balance of System Components

Thermosiphon System Assorted vents and valves Copper piping Insulation

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

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

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

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

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

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

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

How to Purchase Contact reputable solar companies

www.flaseia.org www.findsolar.com

Verify contractor licenses www.myfloridalicense.comVoice: 850-487-1395 Solar contractor (CV) Specialty solar (CW) Plumbing contractor (CF) Local solar license (RX)

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

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)

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

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)

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

Interaction of Incentives

Example –System cost: $4,000State rebate: - $500PEF rebate: - $450Actual cost: $3,050

Federal tax credit: (.30 x 3,050) = $915Net system cost: $2,135

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

For More Information www.flaseref.org www.flaseia.org

www.fsec.ucf.edu www.floridaenergy.org

800-59SOLAR

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