Zero Energy Swimming Pool

1
Zero Energy Swimming Pool

• Bruce L. Hesher
• 433-5779

2
Permitting

• Before doing any electrical or roof work
  consult your local Authority Having Jurisdiction
  (AHJ) to determine the permitting requirements.
  The AHJ is usually the permitting office or
  municipal building department.
• This project was done with no roof
  penetrations except the mounting lag bolts for
  the PV mount rails.

As a home owner you can pull a permit to
install PV and/or solar pool heating equipment on
your own home but, it still must pass inspection.
To pull a permit in a commercial setting, you
must be properly licensed!
To qualify for rebates and/or incentives the
installation may need to be done by a licensed
person, check it out before commencing.
3
Scope

• This presentation describes a renewable energy
  approach to maintaining a swimming pool without
  buying electricity. By targeting a high
  electricity cost item like the swimming pool
  pump, short payback periods can be seen.
• The example in this presentation uses solar
  panels and passive water heating techniques that
  can meet all the needs of an in-ground swimming
  pool. It was done in 2005. Solar power can be
  used to circulate, filter and heat a swimming
  pool. By design, system only operates during
  the day.

While it did not make financial sense at the
time to do a whole house PV system targeting a
high use device (the pool pump) gave a payback of
less than 4 years in 2005!
4
Energy Survey
The first step to either reducing your energy
bill or producing your own energy consumption is
to determine where it occurs. Most utility
companies, including FPL, have on-line tools to
help you identify where your electricity dollars
go.
An FPL energy survey of my home showed that
27 of my electricity bill was going to power my
swimming pool pump! At 27, or about 50/month,
it was the single largest contributor even
larger than the air conditioner.
5
Equipment and Possible Sources

• Solar modules 2 _at_ 170W (in series for 96V 3.5A)
• DC disconnect switch
• Numerous on-line retailers
• Controller Lorentz PS600.
• Motor and Pump
• Florida Solar Pump www.floridasolarpump.com
  [phone]
• Wire and Conduit
• 6 Copper ground rod
• Misc PVC pipe
• Home improvement store.

6
Equipment Details

• Two 170W 48V DC modules in series provide 340W
  at 96V and 3.54Amps. One HP 746Watts so, this
  system is equivalent to about a ½ HP motor.

Aluminum mounting rails are mounted to the
roof using 5/16 lag bolts that go into the
trusses. The panels are bolted to the rails.
The panels can easily be removed in order to ride
out a storm in the garage.
Safety note 96V at 3.5 Amps can be
dangerous. Cover the panels with cardboard or
black plastic while assembling or working on the
system ! A sheet of cardboard cut from the
shipping box and duct tape work well.
7
Wiring and Electrical Conduit
Three wires are needed positive and negative
from the modules and a ground wire. The gauge of
the wire must meet the requirements of the
National Electrical Code (NEC). The nameplate
on the back of the modules states the short
circuit current (Isc) as 4A. As per section 690
of the NEC, the current must be de-rated for 125
of the maximum Isc and for roof temperatures.
90C rated wire on a roof at temps up to 50C
must be de-rated to 82 of its ampacity as per
table 310.16 of the 2008 NEC. So
(4A 1.25) / 0.82 6.1A Consult the American
Wire Gauge (AWG) table for the minimum acceptable
wire size and use at least one size larger. Use
stranded copper wire so that you can feed it
through conduit. Use metal or UV rated PVC
conduit ! If the conduit will penetrate the
roof, most AHJs require metal conduit.
8
Module Placement

• Locate the modules on a south sloping roof at a
  tilt angle close to the latitude. The roof slope
  is usually fine for the tilt angle.

9
Controller

• Electricity from the panels goes to a
  controller that interfaces between the power
  source (modules) and the load (motor/pump).

Safety note Make sure the switch on the
controller box is turned off while assembling.
10
Filter Plumbing

• Size the plumbing to the largest standard size
  that is practical in order to reduce backpressure
  and move more water.

A continuous ground wire from panels runs inside
conduit to the chassis of controller then down to
the pump and 6 copper ground rod driven into the
ground.
Valves in the return line to the pool are used to
divert some of the water through a passive solar
collector in order to warm the water.
11
Pump
A 6 Copper ground rod with wire to both pump and
controller.
12
Heating the Pool

• It takes a lot of energy to raise the
  temperature of water! Passive solar heating that
  does not involve any energy storage or conversion
  is desirable.

A solar blanket that prevents evaporative
heat loss by the pool and/or a solar collector on
the return line to the pool are good options.
13
Performance

• The system moves more water daily than the
  original ½ HP motor connected to the electric
  utility. The exact amount depends on the
  irradiance of the day. It has a flow rate in full
  sun equal to the original motor/pump but runs
  whenever the sun is shinning.
• The system is significantly quieter than the
  original motor/pump.
• Cleaning the pool is done by a Hayward
  PoolVacXL attached to the skimmer.

14
Financial Review (as built in 2005)
Cost breakdown panels 1,600.00 2 -
170W at 800 each Controller 700.00
Lorentz model PS600 DC Pump 600.00
Speck Pumps Filter
200.00 Hayward plumbing 2" PVC 150.00
Home Depot wire conduit 150.00
Home Depot 3,400.00 30 tax rebate
1,200.00 cost after rebate
2,200.00 monthly savings
50.00 payback months 44
The total cost of this system in 2005 was
3,400. This yields a payback of 68 months, 44
after incentives. The system has a life
expectancy of over 30 years on the panels and
10-12 years on the controller and pump. Reduced
equipment costs since 2005 make the payback much
better!
15
System Review in 2013

• After 8 years of operation the system is still
  working flawlessly. It has the side benefit of
  working when the utility is down so that the
  swimming pool stays clean.
• Equipment costs since 2005 have changed. 340W
  of solar modules that originally cost 1,600 are
  now about 400! The PS600 controller, motor and
  pump can be purchased from Florida Solar Pump for
  about 1,700. This lowers the total cost before
  rebates from 3,400 in 2005 to about 2,500.

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Useful Websites
www.fpl.com Florida Power and Light. Use to
determine where your energy dollars are going.
www.fsec.ucf.edu/en/ Florida Solar Energy Center
. The state of Floridas energy research
institute,
www.easternflorida.edu Eastern Florida State
College. Offers an A.S. degree in Alternative
Energy Systems.
www.builditsolar.com DIY site for solar projects.
www.dsireusa.org This is the website that
details active rebate and tax incentive programs
for alternative energy.