1. basic solar thermal training v3 robert cooley
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INSTALLER TRAINING COURSEMODULE 1 BASIC SOLAR THERMAL
Introduction to SHW Earth Energy Resources US Solar Radiation Why Go Green Why SHW
SHW Technology SHW Components Different Types of SHW Systems
Sizing Solar Domestic Hot Water System Solar Fraction (SFn) and Sizing Guidelines Sizing Dependencies SHW Sizing Other Factors
Auxiliary Heating Basic considerations Preheating Dual Tank Systems
BASIC SOLAR THERMALCOURSE OUTLINE
The mission of the Helio Partner program is to ensure thatHeliodyne installing contractors have acquired the knowledgeand skills to effectively promote Heliodyne products, successfully install Heliodyne products, and to provide lasting customer support to end-users thereby representing the Heliodyne brand in the best possible way and in additionincrease for the dealer: productivity, customer satisfaction,repeat sales and referrals.
BASIC SOLAR THERMALHELIO-PARTNER MISSION
Step 1. Successful completion of in person training or completion of on-line training with 100% passing score on the exam portion. Step 2. Submit to Heliodyne current copy of applicable contractor’s license and proof of liability insurance. Minimum: $1,000,000.00 Step 3. Complete successful installation of a Heliodyne Pro system with proof of performance through Heliodyne’s on-line web monitoring system. Step 4. Sign and return Helio Partner agreement.
BASIC SOLAR THERMALBECOMING A HELIOPARTNER
Helio Partners will have added visibility on the Heliodyne web site dealer locator. The Heliodyne logo will appear nextto Helio Partner’s listing. Homeowners and business owners will be drawn to Helio Partners because they will know that partners have successfully completed training, have installed Heliodyne products, and carry adequate licensing and insurance. Helio Partners will receive preference in receiving leads and referrals that come from trade shows, advertising, and directcontact with Heliodyne.
BASIC SOLAR THERMALHELIOPARTNER BENIFITS
BASIC SOLAR THERMALSolar Resources
BASIC SOLAR THERMALPrograms, Legislation and other Support
• Higher fuel prices• 30% federal tax credit• Tax credits• Grants and cash rebates• Obama stimulus package
Go to: www.dsireusa.org
13
BASIC SOLAR THERMALU.S. Solar Hot Water Industry Growth
14
INTRODUCTION TO SHWEARTH ENERGY RESOURCES
Solar Energy
World Annual Consump.
Uranium
Gas
Oil
Coal
INTRODUCTION TO SHWEARTH ENERGY RESOURCES
INTRODUCTION TO SHWWHY SOLAR HOT WATER
IT’S SUITABLE FOR ALL REGIONS
SHW ( HELIODYNE) GOBI 410Output/day: 22.7 kWhArea: 80 ft2 (2 panels)Installed Cost: $7,000
PV (SHELL SQ 165-PC)Output/day: 22.3 kWhArea: 456 ft2 (18 panels)Installed Cost: $30,000
Hawaii
Alaska
IT’S THE MOST COST-EFFECTIVE RENEWABLE WAY TO HEAT WATER
Solar hot water systems perform efficiently all over the US, from Hawaii to Vermont, and Alaska to Florida.
Introduction to SHW Earth Energy Resources US Solar Radiation Why Go Green Why SHW
SHW Technology SHW Components Different Types of SHW Systems
Sizing Solar Domestic Hot Water System Solar Fraction (SFn) and Sizing Guidelines Sizing Dependencies SHW Sizing Other Factors
Auxiliary Heating Basic considerations Preheating Dual Tank Systems
BASIC SOLAR THERMALCOURSE OUTLINE
1. Collector2. Controller3. Pumps4. Heat Exchanger5. Storage Tank6. Tempering Valve7. Expansion Tank8. Air Vent9. Pressure Relief
Valve10. Auxiliary Energy
12
3
4
10
5
6
7
SHW TECHNOLOGYSYSTEM BASICS AND COMPONENTS
8
9Heat transfer fluid is pumped through the collectors, heated by the sun and circulated to the heat exchanger. The fluid exchange heat to the water in the storage tank and returns to the collector to be reheated. This repeats as long as there is sun or until the tank is charged
SHW TECHNOLOGYCOLLECTORS
THREE TYPES OF COLLECTORS
Unglazed Collectors
Vacuum Tube Collectors
Flat Plate Collectors
BASIC SOLAR THERMALTypes of Thermal Collectors
Evacuated Tube Collectors
Flat –Plate Solar Collectors Unglazed Tube-mat Collectors
Integrated Collector Storage Collectors
85%
of Market
15%
of Market
24
BASIC SOLAR THERMALComparing Collector Technologies
Source:Home Power magazine
SHW TECHNOLOGYCOLLECTORS
UNGLAZED COLLECTORS
PRO Easy to install Inexpensive Short Payback period
CON No insulation Efficiency sensitive to wind
and ambient temperature Low temperature range (75°F - 95°F ) Aesthetics May be considered visually
unpleasing Low durability
Unglazed collectors are typically made of plastic tubes combined into an absorber and used for residential pool heating to extend the pool season
SHW TECHNOLOGYCOLLECTOR
VACUUM TUBE COLLECTORS
PRO Works well at high temperature ranges > 220°F Good for high temperature industrial applications
CON May be considered aesthetically unpleasing Relatively higher maintenance Sensitive to loosing vacuum High installation complexity Relatively expensive Relatively fragileDouble wall glass tube with vacuum
in between or a glass tube with a top seal and a pumped vacuum containing an absorber. The vacuum efficiently insulate the absorber minimizing collector heat loss and sensitiveness to wind and ambient temperature
BASIC SOLAR THERMALEvacuated Heatpipe Technologies
28
The sealed tube contains a small amount of alcohol which vaporizes when heated and condenses when cooled
SHW TECHNOLOGYCOLLECTOR
FLAT PLATE COLLECTOR
PRO Simple and proven technology Low maintenance Highly durability High Performance in Cold and Hot Climates Cost-effective (More energy per Dollar) Easy Installation
CON Relatively heavy to carry Limited temperature range of up to 220°FConsists of an insulated weather
sealed metal box containing the absorber and closed with a transparent cover typically made of tempered glass. Frame
Glass
Insulation
Absorber
BASIC SOLAR THERMALFlat Plate Collector
30
Features:• Extruded aluminum frame• Copper or aluminum absorber • Black paint or blue sputtering• Life expectancy of over 25 years• Rated by SRCCInstallation: Weight: 120 - 160 lbs. full
SHW TECHNOLOGYCOLLECTOR ABSORBER VARIOUS SURFACES
BLACK PAINT Low cost solution Recommended for warm climates with high
solar radiation α = 0.85
ε = 0.25
BLACK CHROME First generation selective surface Tough surface Recommended for cool climates α = 0.95
ε = 0.12
BLUE SPUTTERED State of the art technology Optimal heat absorption with minimal emission Suitable for all types of installations and regions Recommended for cool climates
α: Absorptivity A measure of an object's ability to absorb incident energyε: Emissivity The ability of a material to hold or release heat
α = 0.95
ε = 0.05
BASIC SOLAR THERMALResidential Flush-Mount Arrays
32
BASIC SOLAR THERMALResidential Tilt-up Arrays
33
BASIC SOLAR THERMALResidential Ground Mounted Array
34
BASIC SOLAR THERMALSmall Commercial Systems
35
BASIC SOLAR THERMALLarger Commercial Systems
36
BASIC SOLAR THERMALData Monitoring
40
Types of monitoring• Manually read gauges• Controller with digital display• Wireless remote monitoring• Web based monitoring
SHW TECHNOLOGYCONTROLLERS
T1
T2
The controller senses the temperature in
the collector and the bottom of the
tank and start/stop the pump at
various differential temperatures ∆T.
Pump start setting is usually at 18°∆T,
while pump stop setting is usually at
5°∆T. ∆T start/stop settings are different
to avoid continuous start/stop of the
pump
Design Considerations
Stagnation/Overheating Protection
Provides high limit shut-off by turning off the pump
when a preset tank temperature has been
reached (Typically 180°F)
Other Types Timers Differential pressure
SHW TECHNOLOGYPUMPS
The pumps main function is to circulate
the liquid in the solar loop from the
collectors to the tank or heat exchanger
and back into the collectors. Pumps in
closed loop systems are usually fitted
with a cast iron housing whereas pumps
in open loops with direct contact to the
portable water are fitted with bronze
housing to avoid corrosion
Design Considerations
Pumps needs to cope with the desired static
pressure of the system and overcome the
pressure losses in the pipes, collectors and
water heater and at the same time ensure an
adequate flow rate in the solar loop
Flow Rate
The flow rate in a solar loop is typically set at
0.025 GPM per ft2 of collector
Other Types Variable Speed Pump
Keeps a proper temperature in the collectors,
while using minimum electricity
SHW TECHNOLOGYHEAT EXCHANGERS
THREE TYPES OF HEAT EXCHANGERS
Tube-In-TubeHeat Exchangers
Brazed PlateHeat Exchangers
Tube and Shell Heat Exchangers
SHW TECHNOLOGYHEAT EXCHANGER
TUBE HEAT EXCHANGER
Common tube heat exchanger designs are coil-in-tank, tube in tube, wraparound-tube and tube in shell. Heat transfer occurs when one fluid moves through the inner tube while a second fluid moves in a different direction on the outside of that tube.
PRO Low Flow Rate Less Electricity Not
Costly To Operate Fewer Joints Low fouling factor Good option for high
SFn > 70%
Resistant to high pressure
CON Relatively big in size Has to be insulated
Primary feed
Secondaryfeed
Tubes
Shell
SHW TECHNOLOGYHEAT EXCHANGER
PRO Relatively small in size Relatively inexpensive High efficiency
CON Big fouling factor Thus, sensitive to water
quality Should not be used with SFn above 40%
Higher maintenance required
FLAT PLATE HEAT EXCHANGER
Composed of multiple, thin, slightly-separated plates that have very large surface areas and fluid flow passages for heat transfer. Can be more effective, in a given space, than the shell and tube heat exchanger
BASIC SOLAR THERMALTanks with Heat Exchangers
46
SHW TECHNOLOGYEXTERNAL VS. COIL-IN-TANK HEAT EXCHANGER
Heat Transfer Efficiency
External Coil-In-Tank
EXTERNAL HEAT EXCHANGER
Hot-water tank
COIL IN TANK HEAT EXCHANGER
Stores the water heated by the
collector and is typically larger than
regular water heater to allow adequate
accumulation of solar energy
Design ConsiderationsProper tank stratification (hottest water on top, and coldest at the bottom) is important to have maximum solar hot water efficiency. Tall slim tank with a height equal to 3-4 times diameter is optimal.
Choosing a copper or stainless steel tank over an enameled tank can lengthen the service life significantly but price is likely a factor 3-4. Enameled tanks are fitted with sacrificial anodes and if properly maintained can have a satisfactory service life.
Solar storage tanks should have a proper insulation (min. R16) to minimize heat loss.
SHW TECHNOLOGYSTORAGE TANK
The water in a solar storage tank can get very hot (180 oF) so its important to regulate the HW output temperature to prevent scalding. The tempering valve can be set at different HW output temperatures and automatically mixes the hot solar water with the cold water inlet. Typical set temperature is between 120-140 oF
SHW TECHNOLOGYTEMPERING VALVE
Other Types Anti-Scalding Valve
Like the tempering valve it mixes hot and cold water to deliver water at a preset temperature but functionsalso as a safety valv by closing off the flow if the hot or cold mixing supply fails
From Storage Tank
From Cold Water Line
To FixturesM
SHW TECHNOLOGYEXPANSION TANK
Design ConsiderationsExpansion tank should be designed upon a ratio of the total volume of fluid in system and allow for total potential thermal expansion of fluid
The expansion tank absorbs excess water pressure, and provides overpressure protection which could otherwise damage the plumbing structure or exhaust fluid through the pressure relief valve. Normally pre-charged by manufacturer to a set psi.
DIAPHRAGM
BLADDER
Diaphragm Expansion Tank Sensitive to correct install (Has to be in
vertical position) Relatively large in sizeBladder Expansion Tank The flexible bladder maintains a
constant pressure on the fluid while allowing it to expand and contract as it heats and cools
Not sensitive to correct install Smaller in size
Air valves are either manually operated or automatic and is mounted in the flow to allow air to escape. Air valves should be installed vertically in pipe air locks and/or at the highest point in the solar loop. Air locks will restrict flow of the fluid and reduce the heat transfer in the solar loop.
SHW TECHNOLOGYAIR VENT
Design ConsiderationsSince air valves are typically installed at the collector return the fluid can be very hot (up to 430 oF when stagnating). The air valve thus needs to be compatibility with this temperature. Most standard automatic air valves jams after a few months which is fine since all the air is usually out by then. When refilling its recommended to replace the air valve.
Other Types Micro-bubble air vents
The pressure relief valve protects system components from excessive pressures. Used to control or limit the pressure in the system which can build up by a temperature upset. For solar loops its usually set at 125-150 psi. Offers a higher degree of reliability and is often required through regulations
SHW TECHNOLOGYPRESSURE RELIEF VALVE
Design ConsiderationsMandatory in closed solar loops and should
have a pressure rating lower than other ratings of system components, typically 125 psi
Other Types Temperature-pressure relief valve
Protects system components from
excessive pressures and temperatures.
Typically set at 150 psi and 210°F
SHW TECHNOLOGYTYPES OF SYSTEMS
Thermosyphon
Drain Back
Fully Flooded(Indirect)
Fully Flooded(Direct)
BASIC SOLAR THERMALTypes of SHW Systems
• Open Loop Batch• Non-freeze climates• Lowest cost
54
SHW TECHNOLOGYTYPES OF SYSTEMS
THERMOSYPHONPRO No pump required No controller required Less space required Relatively inexpensive
CON Tank exposed to external environmental
condition Efficiency Reduction Aesthetics May be considered visually
unpleasing Not suitable for cold climates Strong support structure needed Sensitive to poor water quality (scaling) Not Scalable
The thermosyphon system uses natural convection to circulate the liquid in a vertical closed-loop which allows it to operate without a pump or control. Tank will need to be positioned above the solar collector for the natural convection to occur
BASIC SOLAR THERMALIntegrated Collector Storage (ICS)
(also called a batch collector system)
• Simple installation (few parts)
• Mild freeze protection available
• Very economical
• Good for the tropical climates
56
BASIC SOLAR THERMALChinese ICS Solar Water Heaters
57
SHW TECHNOLOGYTYPES OF SYSTEMS
FULLY FLODDED (DIRECT)
PRO Simple and well proven technology Easy to install Cost effective Moderately scalable
CON Pump and controller required Not applicable in climates with temperatures
below 42oF Sensitive to poor water quality (scaling)
The heat transfer fluids in the solar loop stays fully flooded. In warm regions the heat transfer fluid is typically the portable water coming directly from the storage tank or water heater.
SHW TECHNOLOGYTYPES OF SYSTEMS
DRAIN BACK
PRO Provides overheating protection Protects collectors from freeze damage
CON Requires drain back reservoir Can be more complicated to install All pipes
and collectors have to drain back to reservoir Limited to maximum height of pump Limited Scalability
The heat transfer fluid in the collector loop drains into a tank or reservoir whenever the solar pump stops. When drained the system is protected from overheating. In cold climates with freezing, potable water can be used in the collectors as they drain at night or when there is no sun
SHW TECHNOLOGYTYPES OF SYSTEMS
FULLY FLOODED (INDIRECT)
PRO Simple and well proven technology Easy to install Cost effective Easily scalable
CON Pump and controller required Care need to be taken to avoid freeze damage System sizing is critical to avoid overheating
The heat transfer fluids in the solar loop stays fully flooded. In cold regions the heat transfer fluid is typically an antifreeze such as propylene glycol to avoid freeze damage to the collectors. As such the heat transfer from the solar loop to the storage tank is done indirectly using a heat exchanger
Introduction to SHW Earth Energy Resources US Solar Radiation Why Go Green Why SHW
SHW Technology SHW Components Different Types of SHW Systems
Sizing Solar Domestic Hot Water System Solar Fraction (SFn) and Sizing Guidelines Sizing Dependencies SHW Sizing Other Factors
Auxiliary Heating Basic considerations Preheating Dual Tank Systems
BASIC SOLAR THERMALCOURSE OUTLINE
BASIC SOLAR THERMALHot Water Usage
TERMINOLOGY
SIZING SOLAR SYSTEM FOR DHWSOLAR FRACTION (SFn) AND SIZING GUIDELINES
Hot Water Demand = Solar Energy + Aux Heating
Consumption Production
Solar Fraction Considerations SFn of 100% will overheat and create
problems in the summer season An undersized system will not provide a
feasible rate of return on investment
A SFn of around 60-80% is optimal
Solar EnergySolar Energy
Hot Water DemandHot Water Demand
Aux EnergyAux Energy
Hot Water Demand
Solar Energy
Aux Energy
SFn =Solar Energy
Hot Water Demand
Space heating requirements of small low energy house
En
erg
y re
qu
irem
ent
or
gai
n (
%)
Space heating requirements of large house
DHW requirements
Solar yield from160 ft2 collectors
Solar yield from 54 ft2 collectors
SIZING SOLAR SYSTEM FOR DHWSIZING DEPENDENCIES
HOT WATER CONSUMPTION
Load Type (Showers, Baths & hot tubs, Hot water appliances)
Patterns (Morning/Night peaks vs. continuous consumption)
Users (Number of people living in the household)
OTHER FACTORS
Shading (Trees, Buildings)
Space Limitations
COLLECTOR
Tilt of the collector
Orientation in relation to due south
Collector efficiency
LOCATION
Solar Radiation (Intensity)
Climate (Clouds, Fog, etc)
Seasonal Variations (Sun path during seasons, Day Vs. Night)
Design Assumptions:
Domestic hot water temperature 120°F
Glazed flat plate collector with good efficiency
Tilt angle 35° (Optimum)
Orientation Due South (Optimum)
SIZING SOLAR SYSTEM FOR DHWSHW SIZING TO VARIOUS HW LOADS
SFn = 58.6%
Sizing Storage Capacity
1.5 Gl/ft2 of Collector
up to
2.0 Gl/ft2 of Collector
Sizing Collector Array
10 ft2/Pers: Low Hot Water Demand (15 Gl/Pers)
12 ft2/Pers: Average Hot water Demand (20 Gl/Pers)
14 ft2/Pers: High Hot Water Demand (25 Gl/Pers)
Example: Base case (used in following slides)
4 Person Household
Average Consumption (20 Gallons/Person)
GOBI glazed high selective absorber
Location: Boston, MA.
Sizing:
Array: 4 x 12 = 48 ft2 2 GOBI 406
Storage: 48 x 1.5 = 72 Gl 80 Gl
SIZING SOLAR SYSTEM FOR DHWSFn SENSITIVINESS TO COLLECTOR ORIENT.
Change the Orientation to Southeast or Southwest
SFn = 56.5% Base case SFn of 58.6%
Minor deviations from a due south collector orientation does not have a significant
impact on Solar Fraction
79
Design Assumptions:
Base case
Impact on SFn when changing collector orientation to Southeast/Southwest
Impact on SFn when changing collector orientation to East/West
Change the Orientation to East/West
SFn = 41.0% compared to Base case SFn of 58.6%
Significant deviations from due south will require a relative larger collector array from
base case. A factor 2 on East/West orientations provides an adequate SFn. Storage
capacity should be calculated as if collectors were due south, however, using 2 Gl/ft2
SIZING SOLAR SYSTEM FOR DHWSFn SENSITIVINESS TO COLLECTOR TILT
NoteMin. tilt in mild areas is 10° to ensure that rain water drains off the collector. In cold, snowy regions min. tilt is 30° to avoid heavy snow loads on the glass
NoteMin. tilt in mild areas is 10° to ensure that rain water drains off the collector. In cold, snowy regions min. tilt is 30° to avoid heavy snow loads on the glass
80
Design Assumptions:
Base case Impact on SFn with a collector tilt of
+/- 20% Impact on SFn with a collector tilt of
10o or 90o
Change the Collector Tilt to 28o or 42o
SFn = 52% Base case SFn of 58.6%
Minor deviations from an optimum tilt of 35o does not have a significant impact on the SFn
Change the Collector Tilt to 10o or 90o
SFn (10o)= 43.0% and SFn (90o)= 31.0% compared to Base case SFn of 58.6%
Significant deviations from optimum tilt will require a relative larger collector array from
base case. A factor 2 on 10o or 90o provides an adequate SFn. Storage capacity should
be calculated as if collectors were due south, however, using 2 Gl/ft2
SIZING SOLAR SYSTEM FOR DHWSFn SENSITIVINESS TO GEOGRAPHICAL LOC
81
Design Assumptions:
Base case
Impact on SFn when changing geographical location further north
Impact on SFn when changing geographical location to a mild region
Impact on SFn when changing geographical location to a tropical regionChange the Geographical location to Vermont (White River Junction)
SFn = 50% Base case SFn of 58.6%
Minor correction to collector array required especially if orientation and/or tilt is also slightly off
Change the Geographical location to California (San Francisco)
SFn = 66% Base case SFn of 58.6% No corrections needed
Change the Geographical location to Hawaii (Honolulu)
SFn = 84% Base case SFn of 58.6%
Solar fraction is on the high side and could cause over heating problems. Changing the
collector absorber surface from high selective to black paint would be beneficial
82
SHW systems need full sunshine to operate at
peak performance
Shading should be avoided at all times and in
particular between 10 am – 2 pm
SIZING SOLAR SYSTEM FOR DHWOTHER FACTORS
Take in consideration deciduous roof
structure, and shading (trees, chimneys, etc)
Roof conforms to current building codes for
loading
Sun Path
Roof Structure
Introduction to SHW Earth Energy Resources US Solar Radiation Why Go Green Why SHW
SHW Technology SHW Components Different Types of SHW Systems
Sizing Solar Domestic Hot Water System Solar Fraction (SFn) and Sizing Guidelines Sizing Dependencies SHW Sizing Other Factors
Auxiliary Heating Basic considerations Preheating Dual Tank Systems
BASIC SOLAR THERMALCOURSE OUTLINE
AUXILIARY HEATINGPREHEATING
SRCC requires installation of isolation valves to ensure that the solar system can be taken out for service without interrupting the hot water supply.
Tempering valves are typically installed between the two tanks to prevent the HW high temp limit fuses to blow if the solar water is too hot.
Electrical
The solar storage tank is installed in the supply line to the water heater (WH) preheating the water. If the solar supply temperature is above the WH set temperature the heating element will not come on. If not it will heat the water to the desired hot water temperature as normal. The solar controller and the WH controller operates independently
Gas Design Considerations
SHW SYSTEM WITH ELECTRICAL OR GAS WATER HEATERS
AUXILIARY HEATINGSINGLE TANK SYSTEMS
In a standard 2 element electric hot water heater the bottom element should be disconnected. The top element can be connected to power and can serve as an auxiliary heater for the top third of the storage tank
The top element will reheat the top of the tank irrespectively of possible solar gains.
Collector feed tube connects to cold water supply. Collector return tube should ideally exhaust below heating element separately from the hot water supply line to ensure that cold or luke warm water from the solar system does not feed directly into the hot water supply.
SHW SYSTEM WITH ELECTRICAL BACKUPDesign Considerations
The electric heating element functions as back-up when solar energy is not available or when hot water demand exceeds the solar-heated supply
Solar Heat Transfer Appliance
AUXILIARY HEATINGSINGLE TANK SYSTEMS
SHW SYSTEM WITH INSTANTANEOUS (ON DEMAND) WATER HEATERS
The solar storage is installed in the supply line to the on demand heater. If the temperature is above the WH set temperature, the on demand heater will not come on. If it isn't, the WH will heat the water to the desired hot water temperature as normal. The solar controller and the on the demand controller operates independently
On demand heater has to be designed for high water inlet temperature coming from the solar system. If it can’t, it’s recommended to install an automatic temperature sensitive by pass valve around the on demand heater.
The on demand heater has to be modulating i.e. heating to a preset hot water output temperature only. Standard incremental heating is not recommended.
Design Considerations
AUXILIARY HEATINGSINGLE TANK SYSTEMS
Using a bottom fired gas water heater as a solar storage tank with gas as a back up requires an electrical ignited burner which can be connected to a solar controller priority relay or the normally open terminal on relay #2 on the Heliodyne Delta T Pro controller.
A pilot flame burner does not work.
SHW SYSTEM WITH GAS BACKUP
The solar heat transfer appliance is connected directly to the gas water heater provided it has the required storage capacity.
Sol
ar H
eat T
rans
fer
App
lianc
e
Design Considerations
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