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The system design is based on using 30 gallons of hot water per day.
If you look at the analysis of the system below using the WSE flat panels at La Ronge, Saskatchewan from May to November you will realize a saving of 150 pounds of propane.
System will pay for itself in about 7 years
The System will return 15,923.47 CAD of free energy over its life time
System Description
The heart of the system is our SRCC approved Flat Panel, 2 -12 Volt 25 Watt Thin Film Panels, PV driven Solar Thermal Differential Controller and 12 Volt FL2201 Pump.
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WSE Flat Panels
A WSE Polysun analysis and financial considerations has been done for La Ronge area in Saskatchewan
We would be happy to do analysis for your location
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Meteorological data-Overview
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Average outdoor temperature
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33.7 °F
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Global irradiation, annual sum
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375.7 kBtu/ft²
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Diffuse irradiation, annual sum
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146.1 kBtu/ft²
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Financial analysis - Solar thermal
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Purchase costs
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900 CAD
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Life span
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30 years
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Inflation
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3 %
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Increase of energy prices
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6 %
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Propane
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6 CAD/gal; 0.037 CAD/kBtu
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Annual fuel cost savings
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110.022 CAD
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Solar energy cost per kWh
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0.03 CAD
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Payback period
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7 years
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Present value of the system
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15,923.47 CAD
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Net present value
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15,023.47 CAD
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Collector
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WSE Flat Panels
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Data Source
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u138368
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Number of collectors
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1
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Number of arrays
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2
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Total area
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ft²
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22.07
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Total aperture area
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ft²
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19.16
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Total absorber area
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ft²
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19.16
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Tilt angle (hor.=0°, vert.=90°)
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°
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45
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Orientation (E=+90°, S=0°, W=-90°)
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°
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0
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Collector field yield [Casual]
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kBtu
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2,538.4
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Irradiation onto collector area [Esol]
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kBtu
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9,951.2
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Collector efficiency [Casual / Esol]
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%
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25.5
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Direct irradiation after IAM
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kBtu
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6,096.8
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Diffuse irradiation after IAM
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kBtu
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2,918.6
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Hot water demand
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Volume withdrawal/daily consumption
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gal/d
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26.5
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Temperature setting
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°F
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104
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Energy demand [Qdem]
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kBtu
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5,410.8
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Solar thermal energy to the system KBTU,
1 Pound of Propane produces 20KBTU.
Saving about 150 pounds of Propane per year.
----------------------------------------------May--June---July--August-September-October-----------
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2- Temperature Sensors
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Propane Water Tank
( Important to Insulate )
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WSE58 Super Tube System
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The system design is based on using 30 gallons of hot water per day.
If you look at the analysis of the system below using the WSE58 Super Tubes at La Ronge, Saskatchewan from May to November you will realize a saving of 190 pounds of propane.
System will pay for itself in 6 years
The System will return 57,529.672 CAD of free energy over its life time
System Description
The heart of the system is our SRCC and CSA approved WSE58ST, 2 -12 Volt 25 Watt Thin Film Panels, PV driven Solar Thermal Differential Controller and 12 Volt FL2201 Pump.
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Financial analysis - Solar thermal
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WSE58 Super Tube |
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Purchase costs
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1,200 CAD
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Life span
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40 years
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Inflation
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3 %
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Interest
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0 %
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Increase of energy prices
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6 %
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Propane
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6 CAD/gal; 0.037 CAD/kBtu
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Annual fuel cost savings
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157.752 CAD
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Solar energy cost per kWh
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0.02 CAD
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Payback period
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6 years
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Present value of the system
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57,529.672 CAD
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Net present value
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56,329.672 CAD
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WSE58 Super Tube Collector
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Data Source
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u138368
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Number of collectors
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1
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Number of arrays
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1
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Total area
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ft²
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49.41
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Total aperture area
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ft²
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42.905
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Total absorber area
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ft²
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42.9
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Tilt angle (hor.=0°, vert.=90°)
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°
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60
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Orientation (E=+90°, S=0°, W=-90°)
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°
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0
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Collector field yield [Qsol]
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kBtu
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3,608.2
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Irradiation onto collector area [Esol]
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kBtu
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25,635
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Collector efficiency [Qsol / Esol]
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%
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14.1
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Direct irradiation after IAM
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kBtu
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20,187.9
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Diffuse irradiation after IAM
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kBtu
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10,987.8
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Constant
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Volume withdrawal/daily consumption
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gal/d
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30.2
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°F
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122
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kBtu
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7,827.9
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Solar thermal energy to the system KBTU,
1 Pound of Propane produces 20KBTU.
Saving about 190 pounds of Propane per year.
-------------------------------------------May--June--July-August-September-October--------------
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A note about solar powered pumps:
It does seem kind of silly to use an AC circulation pump -why pay your electric utility for Kilowatts of peak use energy when you can get it for free from the sun? The relatively small investment in a solar panel will be recovered in a few years. Solar power is more reliable than our aging power grid which could fail in the middle of a hot sunny day potentially causing a catastrophic system failure. If the collectors heat the glycol fluid above 250 degrees or so it will turn acidic and eventually eat through the pipes. Of course the P/T valve may also blow, dumping fluid and depressurizing the system.
This controller is designed specifically for solar heating applications where the circulation pump is powered by a solar panel or DC power.
The Solar Thermal Controller will improve the performance of any DC powered solar heating system. It will switch power to the pump when it determines that one sensor (S1) is hotter than the other (S2). More importantly, it shuts off the pump when the reverse is true.
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Surge Protection is Built in
Note that the controller contains a surge protector which will protect the electronic motors and other electronics like power optimizer. Any voltage over 40 Volts will be clamped inside the DTC - and shorted back to the PV panel.
DC power sources
The input to the solar controller can come from any source of DC voltage including a solar panel, battery or a Wall power adapter (wall wart). If powering a 10 Watt pump the wall wart should be sized about double the wattage of the pump. So a 10 Watt pump would need a 12 Volt 1.5 Amp adapter.
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FEATURES
· Operates from 3.5 to 24 Volts. 30V MAX!
· Uses standard 10K thermistor temperature sensors
· Ambient Operating Temperature 32 - 158F (0 - 70C)
· Manual override switch has ON/AUTO/OFF to simplify testing
· Green LED load power indicator
· Switches up to 6 Amps (72 Watts)
· Replaceable 6 amp 3AG type fuse inside
· Built in surge protection protects electronic motors
· Under 3mA power consumption (when load is off)
CONTROLS
Inside the unit there is a switch with 3 positions:
ON - load is always on.
AUTO - load only powered if S1 is hotter than S2.
OFF - load is off.
The switch is intended primarily for testing, and should be left in the
AUTO position for normal operation. The green LED will light to let you
know when the load should be operating. When replacing the cover -
be sure that the LED aligns with the hole in the cover.
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Flat plate vs. evacuated tube collectors.
There is an inherent mismatch between the efficiency of PV panels and solar thermal collectors such that the PV will have enough power to run a pump when the collector is not hot enough to be useful. This is most pronounced in cold climates. This is less true of evacuated tube collectors which are more efficient and do not radiate heat the way that flat plate collectors can.
Late in the day when your storage tank has accumulated a lot of heat on a cold sunny day is the point at which you may need to shut off your pump. The collectors are not getting enough sun to generate a higher temperature than the stored water. What happens if the pump continues running is that your stored heat is radiated out from flat plate collectors. With evacuated tubes you are likely to be pumping cooler water into the tank. The controller is designed to prevent this from happening.
Delta-T (aka hysteresis)
What does this mean? Delta is Greek symbol used to denote Difference, and T = temperature. Many other (AC powered) DTC's on the market have an adjustable Delta-T that sets the difference be ween the sensor temperatures before the pump is activated. The controller does not, it
simply switches the pump on the moment one sensor (S1) is hotter than the other (S2) and turns it off the moment that S1 is cooler than S2.
This makes the design simple and guarantees that you are never lowering the temperature
of your stored water - even by a fraction of a degree.
Placement of the sensors must be carefully considered to account for temperature drops across both sides of a heat exchanger.
Sensor location
Pressurized glycol systems.
On single pumped systems (where the heat exchanger is inside the storage tank) the hot (S1) sensor should be mounted to the pipe within 6" of the exit at top of the collector. This ensures a rapid response.
On double pumped systems where one pump circulates the collector to HX and another circulates from HX to storage, the hot (S1) sensor should be attached to the pipe that comes from the collectors about 2-3 feet before it enters the heat exchanger. The controller should then be
used to switch the secondary pump.
The cool sensor (S2) should be located where it measures the lowest temperature of the stored water. This can be the pipe that returns to the heat exchanger from the storage tank, or if you can access the surface of the tank, then attach the sensor to the tank wall about 1/4 from the bottom.
Be sure the sensors are insulated from exposure to ambient air, since this will affect the reading. On pipe runs the sensors can be attached with a pipe clamp and wrapped with insulation.
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