Pitt County Detention Center

1
Pitt County Detention Center
DHW - 36 collectors 1750 gallons storage
Drug Rehab Center
DHW - 48 collectors 2000 gallons storage
2
Homeless Shelter - Salisbury, NC
Durability
25 year old system perfect working condition
New replacement system
3
Common Solar System Types
System Design - How it works
Two main designs in use today - Old New (er)
4
How it works
Pressurized Glycol Systems

• Start with
• Collectors
• Pressurized tank
• Collector Side Exchanger
• Pump

Need a few more things
5
How it works
Pressurized Glycol Systems
1
3
5

• Air Vent
• Expansion Tank
• PRV Drain
• Check Valve
• Heat Dump
• 3-Way Valve
• Fan-Coil Unit
• Pump Control

4
Power failure will defeat overtemp protection
2
6
How it works
Non-pressurized Drainback System

• Start with
• Collectors
• Non-Pressurized tank
• Load Side Exchanger
• Pump

Power failure is normal operating mode
7
Residential DHW
Applications
8
Applications
Residential DHW
9
Applications
Residential SH - Forced Air
Furnace
Blower

• Any Furnace Type
• Gas
• Oil
• Heat Pump with
• Electric Backup

10
Residential SH - Forced Air
Applications
Furnace
Solar Coil
Blower

• Three operational modes
• Solar Only (hot)
• Solar Assist (med)
• Solar Cut Out (cold)

Specify Coil for Low Temp Delivery
11
Residential SH - Room Heater
Applications
12
Residential SH - Radiant Slab
Applications
Boiler
Boiler Pump
Boiler Pump is Circulator
13
Residential SH - Radiant Slab
Applications

• Three operational modes
• Solar Only (hot)
• Solar Assist (med)
• Solar Cut Out (cold)

Boiler
Boiler Pump
Design System for Low Temp Delivery
Solar
Solar Pump
Boiler Pump is Circulator
Solar Connection referred to as Side Arm
14
Residential SH - Radiant Slab
Applications

• Three operational modes
• Solar Only (hot)
• Solar Assist (med)
• Solar Cut Out (cold)

Boiler
Boiler Pump
Design System for Low Temp Delivery
Solar
Solar Pump
Loop Pump is Circulator
Solar Boiler Connections are Side Arm
15
Applications
Commercial DHW
16
Applications
Commercial DHW
17
Applications
Commercial Space Heating
Forced Air
Radiant Slab
18
Applications
Commercial Space Heating
Forced Air
Radiant Slab
Design for Low Temp Delivery
19
Applications
Pool Heating
20
Applications
Pool Heating
21
Solar Analysis Methods A Quick Review
1. Load Estimation

• Monthly Hot Water Loads MBtu/mo
• Usually from GPD x Occupants x dT rise
• Ground water temp can be problem
• Duty cycle - monthly variations
• Dorm, Beach/Mountain Business, Hotel
• Result is table of Monthly Energy Loads
• Not capacity.

22
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.

23
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

24
1
2
3
The F-Chart Program
4
Retscreen is free version
5
6
7
8
25
Program Results Printout
26
Results
27
Economics - the simple version
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.
28
Q A
Contact Info
Ben Gravely, President Holocene Technologies 1241
Wicker Drive Raleigh, NC 27604 Cell
919-818-1879 Email ben.gravely_at_holocene-energy.co
m Blog www.solarhotwater-systems.com