Zero Energy Zero Energy Swimming PoolSwimming Pool

Bruce L. HesherBruce L. Hesher

433-5779433-5779

PermittingPermitting 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 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 solar pool heating equipment on your own home but, it still must pass inspection. To pull a permit in a commercial must pass inspection. To pull a permit in a commercial setting, you must be properly licensed!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.

Scope

This presentation describes a This presentation describes a renewable energy approach renewable energy approach to maintaining a swimming poolto maintaining a swimming pool without buying electricity. By without buying electricity. By targeting a high electricity cost item like the swimming pool targeting a high electricity cost item like the swimming pool pump, short payback periods can be seen.pump, short payback periods can be seen.

The example in this presentation uses solar panels and The example in this presentation uses solar panels and passive water heating techniques that can meet all the needs passive water heating techniques that can meet all the needs of an in-ground swimming pool. It was done in 2005. Solar of an in-ground swimming pool. It was done in 2005. Solar power can be used to circulate, filter and heat a swimming power can be used to circulate, filter and heat a swimming pool.pool. By design, system only operates during the day.

While it did not make financial sense at the time to do a While it did not make financial sense at the time to do a whole house PV system; targeting a high use device (the whole house PV system; targeting a high use device (the pool pump) gave a payback of less than 4 years in 2005!pool pump) gave a payback of less than 4 years in 2005!

Energy SurveyEnergy Survey The first step to either reducing your energy bill or The first step to either reducing your energy bill or producing your own energy consumption is to determine producing your own energy consumption is to determine where it occurs. Most utility companies, including FPL, where it occurs. Most utility companies, including FPL, have on-line tools to help you identify where your electricity have on-line tools to help you identify where your electricity dollars go.dollars go.

An An FPL energy survey of my home showed that 27% of of my home showed that 27% of my electricity bill was going to power my swimming pool my electricity bill was going to power my swimming pool pump! At 27%, or about $50/month, it was the single largest pump! At 27%, or about $50/month, it was the single largest contributor; even larger than the air conditioner.contributor; even larger than the air conditioner.

Equipment and Possible Sources

Solar modules: 2 @ 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 (888)282-2119

Wire and Conduit:

6’ Copper ground rod:

Misc PVC pipe:

Home improvement store.

Equipment DetailsEquipment Details

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

Aluminum mounting rails are are mounted to the roof using 5/16” mounted to the roof using 5/16” lag bolts that go into the trusses. lag bolts that go into the trusses. The panels are bolted to the rails. The panels are bolted to the rails. The panels can easily be The panels can easily be removed in order to ride out a removed in order to ride out a storm in the garage. storm in the garage.

Safety noteSafety note: 96V at 3.5 Amps can be dangerous. Cover : 96V at 3.5 Amps can be dangerous. Cover the panels with cardboard or black plastic while assembling the panels with cardboard or black plastic while assembling or working on the system ! A sheet of cardboard cut from the or working on the system ! A sheet of cardboard cut from the shipping box and duct tape work well.shipping box and duct tape work well.

Wiring and Electrical ConduitWiring and Electrical Conduit

Three wires are neededThree wires are needed:: positive and negative from the positive and negative from the modules and a ground wire. The gauge of the wire must meet modules and a ground wire. The gauge of the wire must meet the requirements of the National Electrical Code (the requirements of the National Electrical Code (NECNEC). The ). The nameplate on the back of the modules states the short circuit nameplate on the back of the modules states the short circuit current (Isc) as current (Isc) as 4A4A. As per section 690 of the NEC, the . As per section 690 of the NEC, the current must be de-rated for current must be de-rated for 125%125% of the maximum Isc of the maximum Isc andand for for roof temperatures. 90°C rated wire on a roof at temps up to roof temperatures. 90°C rated wire on a roof at temps up to 50°C must be de-rated to 50°C must be de-rated to 82%82% of its ampacity as per table of its ampacity as per table 310.16 of the 2008 NEC.310.16 of the 2008 NEC. So: (So: (4A4A **1.251.25) /) / 0.820.82 == 6.1A6.1A Consult the American Wire Gauge (Consult the American Wire Gauge (AWGAWG) table for the ) table for the minimum acceptable wire size and use at least one size minimum acceptable wire size and use at least one size larger. Use stranded copper wire so that you can feed it larger. Use stranded copper wire so that you can feed it through conduit. Use metal or UV rated PVC conduit ! through conduit. Use metal or UV rated PVC conduit ! If the If the conduit will penetrate the roof, most AHJ’s require metal conduit will penetrate the roof, most AHJ’s require metal conduit.conduit.

Module PlacementModule Placement

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

Controller 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.

Filter & PlumbingFilter & 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.

PumpPump

A 6’ Copper ground rod with wire to both pump and controller.

Heating the PoolHeating 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.

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.

Financial Review (as built in 2005)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!

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.

Useful WebsitesUseful 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 Florida’s energy research institute,

www.easternflorida.edu Eastern Florida State College. Offers an A.S. degree in Alternative Energy Systems.

www.dsireusa.org This is the website that details active rebate and tax incentive programs for alternative energy.

www.builditsolar.com DIY site for solar projects.