FLORIDA SOLAR ENERGY CENTER
Creating Energy Independence Since 1975
A Research Institute of the University of Central Florida
Northern Climate System TypesNorthern Climate System Types
System TypesSystem TypesSystem TypesSystem Types
ActiveActive Uses a pumpUses a pump
PassivePassive Does not use a pump – relies on natural forcesDoes not use a pump – relies on natural forces
Active SystemActive SystemActive SystemActive System
A pump circulates heat transfer liquid through the collector.
Solar collectorSolar collectorSolar collectorSolar collector
System typesSystem typesSystem typesSystem types
DirectDirect City potable (or well) water is circulated from the tank City potable (or well) water is circulated from the tank
to the collector and backto the collector and back For warm climatesFor warm climates
IndirectIndirect Fluid circulating through the collector never comes in Fluid circulating through the collector never comes in
contact with the city potable water in the storage tankcontact with the city potable water in the storage tank A heat exchanger is used to transfer heat from the A heat exchanger is used to transfer heat from the
circulating fluid to the potable watercirculating fluid to the potable water For cold climates - freezeFor cold climates - freeze
System typesSystem typesSystem typesSystem types
Available System TypesAvailable System TypesAvailable System TypesAvailable System Types
Active indirect using a differential controller Active indirect using a differential controller and flat plate collectorsand flat plate collectors
Active indirect drainback using a differential Active indirect drainback using a differential controllercontroller
Indirect thermosiphonIndirect thermosiphon
Closer look at each systemCloser look at each systemCloser look at each systemCloser look at each system
What makes the system uniqueWhat makes the system unique Basic operation and componentsBasic operation and components Freeze prevention mechanismsFreeze prevention mechanisms Maintenance requirementsMaintenance requirements Advantages and disadvantages of direct and Advantages and disadvantages of direct and
indirect systemsindirect systems
Thermosiphon SystemThermosiphon SystemThermosiphon SystemThermosiphon System
Thermosiphon SystemThermosiphon SystemThermosiphon SystemThermosiphon System
Thermosiphon SystemThermosiphon SystemThermosiphon SystemThermosiphon System
Thermosiphon SystemThermosiphon SystemThermosiphon SystemThermosiphon System
Passive systemPassive system No pump or controllerNo pump or controller
Thermosiphon actionThermosiphon action
Simple, reliable systemSimple, reliable system
Thermosiphon SystemThermosiphon SystemThermosiphon SystemThermosiphon System
Considerations Considerations ++ Simplicity, ease of understanding by service Simplicity, ease of understanding by service
personnelpersonnel Most common system internationallyMost common system internationally
Considerations -Considerations - InstallationInstallation Weight on roofWeight on roof Heat transfer fluids – periodic checkHeat transfer fluids – periodic check
Active Indirect SystemActive Indirect System
Active Indirect SystemActive Indirect SystemActive Indirect SystemActive Indirect System
Two typesTwo types Indirect using a Indirect using a
Heat exchangerHeat exchangerDifferential controller Differential controller Anti-freeze solutionAnti-freeze solution
Indirect drainback using a Indirect drainback using a Heat exchangerHeat exchangerDifferential controllerDifferential controllerDrainage of fluid from collectorDrainage of fluid from collector
Indirect DrainbackIndirect DrainbackIndirect DrainbackIndirect Drainback
Key feature is that the heat transfer liquid in Key feature is that the heat transfer liquid in the collector and collector loop drains back the collector and collector loop drains back into a drainback reservoirinto a drainback reservoir
When drained, there is no liquid in the collector When drained, there is no liquid in the collector to freezeto freeze
Indirect DrainbackIndirect DrainbackIndirect DrainbackIndirect Drainback
System includes a drainback reservoirSystem includes a drainback reservoir Also uses a differential controlled to regulate pump Also uses a differential controlled to regulate pump
operationoperation Heat exchanger is also incorporated into the system. Heat exchanger is also incorporated into the system.
Can be:Can be: Within the drainback reservoirWithin the drainback reservoir Within the solar tankWithin the solar tank
Collector and collector loop piping must be sloped to Collector and collector loop piping must be sloped to allow proper drainback allow proper drainback
Indirect DrainbackIndirect DrainbackIndirect DrainbackIndirect Drainback
Indirect DrainbackIndirect DrainbackIndirect DrainbackIndirect Drainback
Drainback reservoir
Indirect DrainbackIndirect DrainbackIndirect DrainbackIndirect Drainback
Freeze protection Freeze protection All fluid drains from the collector and collector All fluid drains from the collector and collector
looploop Fail safe method but piping and collector must Fail safe method but piping and collector must
be sloped to allow complete drainagebe sloped to allow complete drainage In colder climates glycol is mixed with water for In colder climates glycol is mixed with water for
added freeze securityadded freeze security
Indirect DrainbackIndirect DrainbackIndirect DrainbackIndirect Drainback
Considerations +Considerations +
Positive freeze protectionPositive freeze protection
Thermal energy from collector is conserved in Thermal energy from collector is conserved in drainback tanks – not lost in exposed drainback tanks – not lost in exposed collectorscollectors
Indirect DrainbackIndirect DrainbackIndirect DrainbackIndirect Drainback
Considerations –Considerations – Collectors have to withstand dry stagnationCollectors have to withstand dry stagnation Required elevation differences between Required elevation differences between
collectors and drainback tankscollectors and drainback tanks Higher collector loop pump capacity requiredHigher collector loop pump capacity required Collector and piping must be carefully installed Collector and piping must be carefully installed
to provide positive drainto provide positive drain
Indirect Pumped SystemIndirect Pumped System
Indirect Pumped SystemIndirect Pumped SystemIndirect Pumped SystemIndirect Pumped System
Use where freezing is commonUse where freezing is common Anti-freeze heat transfer fluidAnti-freeze heat transfer fluid Heat exchangerHeat exchanger
Internal or externalInternal or external Expansion tankExpansion tank Differential controllerDifferential controller Various valvesVarious valves
Indirect Pumped SystemIndirect Pumped SystemIndirect Pumped SystemIndirect Pumped System
Indirect Pumped SystemIndirect Pumped SystemIndirect Pumped SystemIndirect Pumped System
Considerations +Considerations + Freeze protection provided by anti-freeze fluidFreeze protection provided by anti-freeze fluid
glycolsglycols Collector loop remains full and pressurizedCollector loop remains full and pressurized Careful sloping of piping is not criticalCareful sloping of piping is not critical
Indirect Pumped SystemIndirect Pumped SystemIndirect Pumped SystemIndirect Pumped System
Heat transfer properties of antifreeze fluids inferior to Heat transfer properties of antifreeze fluids inferior to water – reduced performancewater – reduced performance
Periodic maintenance required to ensure heat transfer Periodic maintenance required to ensure heat transfer fluid properties have not deterioratedfluid properties have not deteriorated
Collectors and antifreeze have to withstand stagnation Collectors and antifreeze have to withstand stagnation when summer load is satisfied early in daywhen summer load is satisfied early in day
Venting through T-P valve under stagnation Venting through T-P valve under stagnation conditionsconditions If excessive will require refilling of system to proper If excessive will require refilling of system to proper
operating pressureoperating pressure
System CertificationSystem CertificationSystem CertificationSystem Certification
Systems installed should be certified to Systems installed should be certified to insure product safety and proper design insure product safety and proper design
Florida Solar Energy Center (Florida)Florida Solar Energy Center (Florida)www.fsec.ucf.eduwww.fsec.ucf.edu
Solar Rating & Certification Corporation Solar Rating & Certification Corporation (National)(National)www.solar-rating.orgwww.solar-rating.org
Listing of Renewable Listing of Renewable EnergyEnergy
Listing of Renewable Listing of Renewable EnergyEnergy
www.dsireusa.orgDSIRE is a comprehensive source of information on state, local, utility, and federalincentives that promote renewable energy and energy efficiency.