Home Energy

1. Home Energy Bruce L. Hesher Brevard Community College Engineering Technology Energy Systems 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.

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 swimming pool, short paybacks can be seen. Additionally with modification the system described in the presentation could provide power to critical loads during extended power outages such as those after a hurricane. 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 built in 2005. Solar power can be used to circulate, filter and heat a swimming pool. A swimming pool can be the single largest power consumer in the home.

4. Energy Survey The first step to either reducing your energy bill or producing your own power is to determine where your energy consumption occurs. Most utility companies, including FPL, have on-line tools to help you identify where your electricity dollars go. An 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 slice of the pie even larger than the air conditioner. Contact your local permitting office to determine what is required. As a home owner you can install PV and/or solar pool heating equipment on your own home but, it must pass inspection. To pull a permit in a commercial setting, you must be properly licensed!

5. Target Power Hungry Items Two 170W 48V DC modules in series provide 340W at 96V and 3.54Amps. Aluminum mounting rails are mounted to the roof using 3/8” lag bolts that go into the trusses. The panels are bolted to the rails using 7/16” bolts. 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 !

6. 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 sates 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 Iscand for roof temperatures. 90°C rated wire on a roof at temps up to 50°C 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 appropriate wire size. Use stranded wire so that you can feed it through the conduit. Use metal or UV rated PVC conduit !

7. Module Placement Locate the modules on a south sloping roof at a tilt angle close to the latitude.

8. Controller Electricity from the panels goes to a controller that interfaces between the power source (modules) and the load (pump). Lorentz model PS600 Safety note: Make sure the switch on the controller box is turned off while assembling.

9. Filter & Plumbing Size the plumbing to the largest standard size that is practical in order to reduce backpressure and move more water. Ground wire from panels runs inside conduit to chassis of controller then down to pump and ground rod driven into water table. 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.

10. Pump • A continuous ground from the panels to the controller to the pump and to ground is needed. 6’ Copper ground rod with wire to both pump and controller.

11. 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.

12. Financial Review 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 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!

13. Related Websites American Council for an Energy-Efficient Economy (ACEEE),www.aceee.org 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.brevardcc.edu Brevard Community College www.dsireusa.org This is the website that details active rebate and tax incentive programs for alternative energy.