Solar System Design Basics

James M. Pleasants Company, Inc. 800-365-9010

James M. Pleasants Company

www.jmpco.com

Availability of Solar Energy

• Solar constant at mean earth-sun distance

• 441 Btu/h · ft2 winter and 413.1 Btu/h · ft2 summer

• Solar Insolation is total radiation earth

1. Direct Solar radiation (()88 to 95%)

2. Diffuse Solar radiation

3. Reflected Solar radiation

2011 ASHRAE HANDBOOK

HVAC Applications

I-P Edition

Supported by ASHRAE Research 4

CHAPTER 35 SOLAR ENERGY USE

QUALITY AND QUANTITY OF SOLAR ENERGY

Solar Constant

…The current value of the solar constant (which is defined as the intensity of solar radiation on a surface normal to the sun’s rays, just beyond the earth’s atmosphere at the average earth-sun distance) is 433 Btu/h · ft2. Chapter 15 of the 2009 ASHRAE Handbook-Fundamentals has further information on this topic.

413.1 Btu/h · ft2 Summer

441 Btu/h · ft2 Winter

The Earth is closest to the Sun in the Winter 6 http://en.wikipedia.org/wiki/Seasons

Earth’s yearly revolution around the sun

Earth revolves around the sun once per year. The axis of rotation points in the same direction throughout the yearly trip.

April March February May January

June 23.5o

July December

August November

September October

7 http://www.classzone.com/books/earth_science/terc/content/visualizations/es0408/es0408page01.cfm?chapter_no=visualization

Earth’s yearly revolution around the sun

Earth revolves around the sun once per year. The axis of rotation points in the same direction throughout the yearly trip.

April March February May January

June 23.5o

July December

August November

September October

8 http://www.classzone.com/books/earth_science/terc/content/visualizations/es0408/es0408page01.cfm?chapter_no=visualization

Solar Insolation is total radiation earth

Direct Solar radiation (88 to 95%)

Diffuse Solar radiation

Reflected Solar radiation

Solar Irradiance

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United States Solar Irradiance

C/O National Renewable Energy Laboratory Resource Assessment Program 14

Solar Energy Definitions • Latitude and Longitude • Solar Sky Position (altitude, inclination & azimuth) • Daily Solar Time (AM through PM) • Collector Tilt Angle (Shade Effect) • Atmospheric Clearness Factor • % Sunshine per Month (Smog) • Isogonic Chart USA • SRCC - “SOLAR RATING & CERTIFICATION CORP” • Stagnation “Where to Put the Heat?” • Solar Fraction (% fuel saved) • REC “Renewable Energy Certificates” 16

Latitude: The angular distance north or south of the earth's equator, measured in degrees. Lines appear horizontal.

Arctic Circle

Tropic of Cancer

Tropic of Capricorn

Antarctic Circle

Longitude: The angular distance on the earth's surface, measured east or west. Lines appear vertical.

CHAPTER 35 SOLAR ENERGY USE

QUALITY AND QUANTITY OF SOLAR ENERGY

Solar Time Solar Sky Position (altitude, inclination & azimuth)

18 Fig. 1 Apparent Daily Path of the Sun Showing Solar Altitude (ß) and Solar Azimth (ɸ)

Direction & Inclination

Solar Altitude (or Solar Elevation from Horizon) Solar Altitude is the angular height of the sun measured from the Horizon. Above the horizon is positive, below is negative. The sun directly in the centre of the sky has a Solar Altitude of 90 degrees.

Solar Elevation angle Sun height, height angle, solar altitude angle or elevation is the angle between a line that points from the site towards the centre of the sun, and the horizon.

Angle of Inclination The angle of inclination (angle between the equatorial plane of the earth and the orbital plane of the satellite) This is the direction of a celestial object, measured clockwise around the observer’s horizon from north. So an object dthhithf0due north has an azimuth of 0o, one dt90due east 90o, south 180o and wes t 270 o. Azimuth and altitude are usually used together to give the direction of an object in the topocentric coordinate system. Sometimes, south is used as the starting point for azimuth angles instead of north. The solar azimuth angle is the azimuth angle of the sun. It is most often defined as the angle from due north in a clockwise direction. 21

Daily Solar Time (AM through PM)

Greensboro, North Carolina 36° 4' 21" N / 79° 47' 32" W

Longest day of the year… June 21st - First day of Summer

Sunrise: 6:03 am Solar noon: 1:21 pm Sunset: 8:39 pm Day Length: 14 hours 37 minutes

Shortest day of the year… December 21st - First day Winter

Sunrise: 7:26 am Solar noon: 12:17 pm Sunset: 5:09 pm Day Length: 9 hours 42 minutes 26

April 1977 35

Collector Tilt Angle “Shade Effect”

TILT INCREASE RELATIVE HORIZONTAL COLLECTING SURFACE AREA

• The angle of your solar collector should roughly equal the latitude of your location (± 10 degrees ok)

• In the Northern Hemisphere: Your collector should face South

• In the Southern Hemisphere: Your collector should face North 36

Collector Tilt Angle

FIGURE 2.3 EFFECT OF TILT ANGLE ON INSOLATION

Software available: F - Chart, Polysun 37

Angle of Tilt

CHAPTER 35 SOLAR ENERGY USE

QUALITY AND QUANTITY OF SOLAR ENERGY Solar Radiation at the Earth’s Surface

Atmospheric Clearness Factor

39 Fig. 5 Clearness Numbers for the United States

% Sunshine per Month

Shows Average Daily Sunlight Hours Available For Solar Electric (Solar PV) Panels

40 http://www.solarpanelsplus.com/solar-panels/large-insolation-map.html

Urban Area Smog Correction

Isogonic Chart USA

FIGURE 2.4 ISOGONIC CHART OF THE UNITED STATES 42

SRCC - “SOLAR RATING & CERTIFICATION CORP”

OG-100

Stagnation “Where to Put the Heat?”

Stagnation is something you need to be aware of…

• Simply put, stagnation is when there is heat available in the collector but no place to store it

• The end result is the small amount of fluid in the collector flashes to steam

• When this occurs, no more heat will be available to collect until the system cools down

Stagnation “Where to Put the Heat?”

• Potential to occur exists in most systems • Minimize its effects by • Proper sizing of the storage tank

• Proper sizing of the expansion tank

• Using a good evacuating collector (serpentine)

• Using a good quality glycol

Stagnation “Where to Put the Heat?”

Expansion Tank

Cold Inlet 47

Solar Fraction (% fuel saved) The solar fraction (SF) is the ratio of the energy supplied by the solar system to the total energy required by the process. Note that, for small collector areas, a relatively small increase in collector area leads to a steep increase in solar fraction. As the collector area is increased, however, each addition al square foot of collector area yields a smaller increase in solar fraction. The selection of the optimum collector area for a gggyyiven building system is ultimately an economic decision, as the cost of additional collector area and system capacity must be weighed against the diminishing return in solar fraction gained.

* 30% Solar Fraction a good place to begin when looking for the fastest payback. 48

REC “Renewable Energy Certificates”

Duke Energy Carolinas Renewable Energy Certificates (“RECs”) Standard Offer

* One “REC” is equivalent to 1,000 KWH 49

Duke Energy Carolinas Standard Purchase Offer for Renewable Energy Certificates (“RECs”)

North Carolina has enacted a Renewable Energy and Energy Efficiency Portfolio Standard (“REPS”) to diversify electricity generation resources and to encourage investment in renewable energy technologies.

In order to comply with the REPS requirements Duke Energy Carolinas plan to develop renewable energy and energy efficiency resources and purchase Renewable Energy Certificates (“RECs”). RECs represent the renewable energy or “green” attribute of renewable energy supply and will be used to document compliance with the North Carolina REPS law. A REC is equivalent to one megawatt hour (1,000 KWH) of renewable energy supply.

Customer’s facility must generate RECs from one of the approved renewable energy resources under NC REPS (e.g. solar electric, solar thermal, wind, hydropower, geothermal or ocean current, a wave energy resource, biomass resource, landfill methane, waste heat derived from a renewable resource, or hydrogen derived from a renewable resource).

Solar RECs Purchase Agreements must provide a minimum of 35 RECs (35 MWH equivalent) per year up to 250 RECs (250 MWH equivalent) per year. For example, a 25 kilowatt solar PV system will produce approximately 35 RECs per year. Projects that are able to provide more than 250 solar RECs per year are not eligible for this standard offer and should submit an unsolicited bid proposal to supply energy and/or RECs to Duke Energy. (see http://www.duke-energy.com/suppliers/carolinas-rfp.asp )

Minimum term for RECs Purchase Agreements if five (5) years, up to a maximum term of fifteen (15) years.

Solar Collectors and Types

• Photovoltaic Panels

• Wind Turbines

• Forced Air & Hydronic Liquid Collectors

1. Fixed Flat Plate Collectors

2. Tracking Collectors

3. Reflected Collectors

Solar Photovoltaic Panel Sizing

Atlanta, Georgia

Solar Photovoltaic Panel Sizing

Types of Solar PV Panels Required The are 3 basic types of construction of PV panels though all use silicon. They are monocrystalline, polycrystalline, and amorphous. The SC circulators are recommended f or use with monocryst alli ne PV panel s. Alt houg h polycrystalline PV panels can be used, they are less efficient at producing electrical energy compared to the monocrystalline panels.

Monocrystalline Monocrystalline cells are cut from a single crystal of silicon- they are effectively a slice from acrystal.a crystal. In appearance, it will have a smooth texture and you will be able to see the thickness of the slice. These are the most efficient and the most expensive to produce. They are also rigid and must be mounted in a rigid frame to protect them. 53

Wind Turbines

Forced Air & Hydronic Liquid Collectors

Fixed Flat Plate Collectors

Basic Flat Plate Construction

“Serpentine“ arrangement: “Harp“ arrangement: -Long copper riser -Shorter copper riser -Higher solar gain -Lower solar gain -Higher pressure drop -Lower pressure drop

Wind Rating

• American Society of Civil Engineers (ASCE) Standard 7-05 • Minimum Design Loads for Buildings and other Structures

Commercial Collectors • SCH Construction • Aluminum Frame, Powder Coated • LiLow iron – .16” pr isma tic sa fe ty g lass • .79” PU20 heat resistant foam • 1.57” Mineral wool insulation • Aluminum absorber with PVD finish • .35” copper tube serpentine • .87” copper header • SRCC Certified • 10-year WtWarranty • 412°F max temp with no flow • 145psi max operating pressure

Types of Hydronic Solar System • Three Interconnected Basic Sub-Systems 1. Collector System 2St2. Storage S yst em 3. Final Terminal System (heating/cooling) • Combined Sub-System Controls • Standby Heating Systems Required • Water or Glycol Solution • Water Drain Back System • “Open Drop” Water Drain Back System • Glycol Collector Sub-System • Heat Exchanger Types • Storage Sub-System and Tank Sizing 59

Product Overview

Tanks

Boiler & Water Heater Collector Back-Up

Pump Stations & Control Piping & Accessories

OG300 – Packaged Solar Thermal Systems

Combined Sub Systems Controls

Differential Control

• Standard Equipment in Pump Stations

• Can be Sold as an Accessory

• Standalone Differential Control

Field Wiring

System Configuration

Preheated Inlet

Expansion Tank

Cold Inlet 65

Figure 10: Drainback System with Electric Backup in Water Heater

Solar Thermal Systems

Basic Drainback System Figure 6 to the right shows a basic indirect drainback solar water heating system. Some key points for this system type: • Reliable systems requiring the least amount of routine service • Great for a wide temperature range. When system pump is off the collector is empty of any water giving it an advantage in extremely cold weather regions • Requires high head pumps as the system pump has a requirement to lift system fluid out of drainback tank to the solar collectors Figure 6

Figure 6: Active Open System

Solar Thermal Systems

Basic Open Loop System Figure 7 to the right shows a basic open loop direct solar water heating system. Some key points for this system type: • Only recommended in tropical settings where freezing is not an issue • Simplest active solar water heating system • Potable water is circulated to and heated at collector • Due to the elevated water temperatures these systems experience, system designers should be mindful of water temperatures above 140°F since minerals may come out of solution Figure 7 above this temperature

Pool Application

Glycol Collector Sub-System

Figure 7: Closed Looped System

Solar Thermal Systems

Basic Pressurized Glycol System Figure 5 to the right shows a basic idiindirect pressuri zed gl ycol sol ar water heating system. Some key points for this system type: • Advantageous because solar collectors can be mounted anywhere • System requires expansion tank and air venting measures • Potable water only circulates to and from solar storage tank and fixtures. Water/glycol mixture circulates through collector and heat exchanger in solar storage tank • Requires circulation pump to move Figure 5 water from collector to storage tank (No pump head required for lift) 72

Example System Design

• Solar Heating Domestic Hot Water

1. Domestic Hot Water “Rule of Thumb”

2. Example Glycol Project

3. Pay Back Analysis and Energy Recovered

• Solar Heating/Cooling Systems

DHW Sizing

• Basics – Rule of Thumb

• HW Demand • Tank Sizing • Collector Sizing • Direction & Inclination • Sizing Guide

Note: The DHW Rule of thumb Sizing is for beginning quick small estimates only and a detailed DHW demand calculation should be done. The JMP CO is not responsible for the sizing of your actual DHW demand!

Sizing Solar Hot Water Systems

General Solar Sizing Rules of Thumb • Domestic Usage: In general figure 20 gallons per day for each person in the household •Flow: 1 GPM flow per collector is a good rule of thumb to use to figure collector flow rate • Domestic Water Solar Storage: Volume of storage tank = square footage of collector x 1.25 ~ 2.0 or 2.0 x daily domestic usage •Btu’s: One sq ft of collector produce between 800 and 1000 BTU’s per day • Drainback tank: Volume of collectors plus volume of piping at or above drainback tank height x 2 for tank size

DHW Sizing

• Hot Water Demand

• 500 Gallons (25 people at 20 GPD)

Tank Sizing

• Sizing of a DW-tank (for Solar):

• Daily DW-usage x 2 = tank-volume

• Using existing volumes is recommended, acceptable parameters allow 10% less or 20% more

Collector Sizing

• Calculation for collector

• Tank volume divided by 2

Making it “Usable”

• DHW Usage per day - 500 GPD • Tank Volume - 1000 gallons • Calculation for collector

• Tank volume divided by 2

• 1000 / 2 = 500 sq/ft panel

A snapshot of Collector information”

Collector Size Sq/ft Weight Volume(gal) Flow Rate GPM hgt x wdt SLH030 3'10" x 7'1" 27.45 102 0.55 0.28

SLV030 7'1"x 3'10" 27.45 102 0.55 0.28

SCH065 6'7" x 9'10" 65.64 309 1.43 0.656

SCH090 6'7" x 13'2" 87.16 411 1.9 0.872

SCH110 6'7" x 16'4" 108.68 513 2.38 1.09

SCH130 67"6.7" x 19'7" 130.2 614 2862.86 131.3

Making it “Usable”

• DHW Usage per day - 500 GPD • Tank Volume - 1000 gallons • Calculation for collector

• Tank volume divided by 2

• 1000 / 2 = 500 sq/ft panel

• 4 ea - SCH130 Collectors = 520 sq/ft

Making it “Usable”

• Pipe Sizing

• In the construction of the collectors, we have narrower serpentine tubing. This is offset with a low flow rate.

• .01 gpm per sq/ft of collector space

Making it “Usable”

• Think about this as a standard closed loop hydronic system and now fill in the blank.

Lower flow rates equate to a higher ∆T and allows SMALLER PIPE SIZE.

4 ea - SCH130 will give us 520 sq/ft

2286Gallonx.86 Gallon x Content = 4 Collector =11.4 gal

Flow rate = 5.2 Gpm

Two minutes of contact time in the collector

Codes, Rebates, Incentives

• ASHRAE 189.1 Standard and Codes

• Utility rebate examples and resources

• Tax code incentives

CHAPTER 7 ENERGY EFFICIENCY 7.3 Mandatory Provisions

731G7.3.1 Genera l. Buildi ng pro jec ts shllbdhall be des igne dtd to comp ly w ith Sections 5.4, 6.4, 7.4, 8.4, 9.4, and 10.4 of ANSI/ASHRAE/IESNA Standard 90.1.

7.3.2 On-site Renewable Energy Systems. Building projects shall provide for the future installation of on-site renewable energy systems with a minimum rating of 3.7 W/ft2 or 13 Btu/h·ft2 (40 W/m2) multilidbthttlltiplied by the total roof area iftin ft2 (m2). Buildi ng pro jec ts didesign shall show allocated space and pathways for installation of on-site renewable energy systems and associated infrastructure.

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Local Incentives

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Local Incentives

Starting in May 2010, California has a program subsidizing the purchase and installation of solar water heating equipment. The program sets aside $358 million for direct economic subsidies and market development support. The program will continue through 2017, or until funding is used completely.

http://www.dsireusa.org/solar/incentives/incentive.cfm?Incentive_Code=TN61F&re=1&ee=1

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Federal Incentives

The Energy Policy Act of 2005 included a new tax incentive, to improve the energy efficiency of commercial buildings. The "Commercial Building Tax Deduction" establishes a tax deduction for expenses incurred for energy efficient building expenditures made by a building owner. The deduction is limited to $1.80 per square foot of the property, with allowances for partial deductions for improvements in interior lighting, HVAC and hot water systems, and building envelope systems. The Emergency Economic Stabilization Act of 2008 (HR-1424), approved and signed on October 3, 2008, extends the benefits of the Energy Policy Act of 2005 through December 31, 2013.

Federal Tax Credits for Consumer Energy Efficiency – 30% Tax credit with no limit (expires 12/31/2016)

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Financial Incentives for Solar Water Heating www.dsireusa.org / April 2011 NH U U $ VT $ MA $ D U $ U U RI $ D U $ U CT $ $U U $ NJ U $ $ U U U $ U DC MD $ U $ U U $ U Puerto Rico D $

D U USU.S. VirginIslandsVirgin Islands $ U U 41 states + DC, PR & USVI offer financial Direct Cash Incentive D Tax Deduction U Utility Direct Cash Incentive(s) incentives for Tax Credit $ Sales Tax Incentive $ Local option to provide sales tax incentive solar water Direct Cash Incentive Local option to provide property tax heating and Tax Credit Property Tax Incentive incentive 104

Efficiency and Renewable Energy Incentives (2011) Alabama

1. Local Government Energy Loan Program: http://www.adeca.alabama.gov/C3/Local%20Government%20Energy%20Loan%20P/default.aspx • Ala bama ’s Loca l Governmen t Energy Loan Program o ffers zero-itinteres tlt loans to l oca l governments and schools for energy efficiency upgrades • Includes boilers, motors, VFD’s, solar water heat, geothermal heat pumps • Up to $350,000 available for local governments or school campuses and up to $500,000 available for school systems

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Efficiency and Renewable Energy Incentives (2011) North Carolina 1. Renewable Energy Tax Credit (Corporate): http://dsireusa.org/incentives/incentive.cfm?Incentive_Code=NC19F&re=1&ee=1 • NC offers tax credit equal to 35% of the cost of renewable energy products • Includes solar and geothermal products • Up to $2.5 million available 2. Active Solar Heating and Cooling Systems Exemption: http://dsireusa. org/incentives/incentiorg/incentives/incentiveve. cfm?Incentive_Code=NC09F&re=1&ee=1 • Active solar heating and cooling systems cannot be assessed at more than the value of a conventional system for property tax purposes • This includes all pumps, tanks, controls, and heat exchangers 3. Progress Energy Carolinas - SunSense Commercial Solar Water Heating Incentive Program: https://www.progress-energy.com/shared/segment-selectors/sunsense.page • Progress Energy will pay $20 for each renewable energy credit generated by the solar water heating system for 10 years • One REC is equivalent to 1 MWh (1,000 kWh = 3,412,000 BTU’s) • Duke Power will pay $30 for 2011 4. North Carolina Green Business Fund: http://www.ncscienceandtechnology.com/gbf/index.htm • Grants are available for sustainable building practices such as renewable energy technology • Up to $500,000 available depending on the award 5. Energy Improvement Loan Program: http://www.nccommerce.com/energy • Program provides loans with a 1% interest rate for renewable energy products • Loans with an interest rate of 3% are available for energy efficient products • Includes boilers, VFD’s, and solar water heaters 106 • Up to $500,000 available

Efficiency and Renewable Energy Incentives (2011) Federal

1. Business Energy Investment Tax Credit: http://dsireusa.org/incentives/incentive.cfm?Incentive_Code=US02F&re=1&ee=1 • The federal business investment tax credit is available for solar and geothermal applications • For solar applications the credit is 30% of expenditures with no maximum • For geothermal applications the credit is 10% of expenditures with no maximum

2. U.S. Department of Treasury - Renewable Energy Grants: http://www.treasury.gov/initiatives/recovery/Pages/1603.aspx • The American Recovery and Reinvestment Act of 2009 created a grant program for renewable energy products including solar and geothermal • For solar applications the grant is equal to 30% of the property • For geothermal applications the grant is equal to 10% of the basis of the property

3USDA3. USDA - Rural Energy for America Program Loan Guarantees: http://www.rurdev.usda.gov/rbs/busp/bprogs.htm • Loans are available for renewable energy technology such as solar water heat and geothermal heat pumps • Loans may be up to 25% of a project’s cost

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USA Today - Thurs. June 21, 2011 “Boom in Solar Power Shines for Consumers” • First QTR 2011 Photovotaic up 66% • United States poised to lead the world • A dramatic decrease in panel cost • Solar City, SunRun and Sungevity • no up front cost and lower electric bills • Solar Thermal panels also reduce electric demand

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Thank you for coming!

Web Site: http://www.jmpco.com 116