Post on 15-Jan-2016
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Pitt County Detention Center
Drug Rehab Center
DHW - 36 collectors1750 gallons storage
DHW - 48 collectors2000 gallons storage
Homeless Shelter - Salisbury, NC
25 year old systemperfect working condition
New replacement system
Durability
System Design - How it works
Two main designs in use today - Old & New (er)
Common Solar System Types
Start with •Collectors•Pressurized tank•Collector Side Exchanger•Pump
Pressurized Glycol Systems
Need a few more things
How it works
1.Air Vent2.Expansion Tank3.PRV & Drain4.Check Valve5.Heat Dump 3-Way Valve Fan-Coil Unit Pump & Control
How it works
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Pressurized Glycol Systems
Power failure will defeat overtemp protection
Non-pressurized Drainback System
Start with •Collectors•Non-Pressurized tank•Load Side Exchanger•Pump
How it works
Power failure is normal operating mode
Residential DHWApplications
Applications Residential DHW
Applications
Furnace
Blower
Residential SH - Forced Air
Any Furnace Type•Gas•Oil•Heat Pump with
Electric Backup
Residential SH - Forced Air
Furnace
Blower
SolarCoil
Applications
Three operational modes•Solar Only (hot)•Solar Assist (med)•Solar Cut Out (cold)
Specify Coil for Low Temp Delivery
Residential SH - Room HeaterApplications
Residential SH - Radiant SlabApplications
Boiler
BoilerPump
Boiler Pump is Circulator
Residential SH - Radiant SlabApplications
Boiler
BoilerPumpSolar
SolarPump
Three operational modes•Solar Only (hot)•Solar Assist (med)•Solar Cut Out (cold)
Design System for Low Temp Delivery
Boiler Pump is Circulator
Solar Connection referred to as “Side Arm”
Residential SH - Radiant SlabApplications
BoilerPumpSolar
SolarPump
Three operational modes•Solar Only (hot)•Solar Assist (med)•Solar Cut Out (cold)
Design System for Low Temp Delivery
Loop Pump is Circulator
Boiler
Solar & Boiler Connectionsare “Side Arm”
Applications Commercial DHW
Applications Commercial DHW
Applications
Forced Air
Radiant Slab
Commercial Space Heating
Forced Air
Radiant Slab
Applications
Design for Low Temp Delivery
Commercial Space Heating
Applications Pool Heating
Applications Pool Heating
Solar Analysis Methods
A Quick Review
•Monthly Hot Water Loads = MBtu/moUsually from GPD x Occupants x dT riseGround water temp can be problem
•Duty cycle - monthly variationsDorm, Beach/Mountain Business, Hotel
Result is table of Monthly Energy LoadsNot capacity.
1. Load Estimation
2. Energy Data (the fuel)
• NASA Satellite data covers the whole earth. Use Lat. & Long.
• Solar Radiation - Btu/ft2 on flat surface• Must tilt radiation data to chosen angle &
south azimuth
• Ground water temp calculated from ambient temp.
3. Choose Solar Collector (the boiler)
• Peformance specs come from certified tests• Listed with SRCC
• Only gain is radiation. Choose number.
• Losses are radiation, convection, and conduction
• Performance is straight line equation. Downward slope indicates lower efficiency as dT increases.
3. Choose Solar Storage (the battery)
• Based on collector area• Can fudge with daylight load
4. Put all the inputs into computer program (the brain)
Result is •monthly calculated loads for SH & HW•monthly solar energy produced•monthly solar fraction•monthly ouput per collector•Annual totals at the bottom
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The F-ChartProgram
Retscreenis free version
Program ResultsPrintout
Results
Current and future cost of energy - First Order Estimates
Example: Solar output = 8 MBtu/collector
Installed cost/coll = $4500
System lifetime = 20 years
Results: Lifetime energy = 160MBtu/coll
Result: Simple Energy Cost over Lifetime = $28.125/ MBtu
= $0.09/kWh
Compare with existing fuel cost of gas, oil, electric (÷ by efficiency)
e.g. 80% efficiency = 1.25X fuel cost
65% efficiency = 1.53X fuel cost
Need threshold energy value for go ahead.
Economics - the simple version
Q & A
Contact Info
Ben Gravely, President
Holocene Technologies
1241 Wicker Drive
Raleigh, NC 27604
Cell: 919-818-1879
Email: ben.gravely@holocene-energy.com
Blog: www.solarhotwater-systems.com