How does it work? The Basics:

"Renewable energy electrical system schematic"

1st. - The Solar Hot Water Heating System:
 

• There are two hot water storage tanks in the basement. These two tanks work in tandem to reduce the need for gas heated hot water.

 

• Cold/cool water comes from the well through the water lines to the basement. This cold water is sent up to the solar water heaters in the yard via a copper pipe.

 

• Each of 3 solar water heaters has a capacity of 0.8 gallons. The sun heats the water as it passes through the heaters. The warmed water returns to the basement to be stored in the hot water storage tank.

 

• A pump, powered by a small solar photo voltaic(PV) panel, circulates the water. This same PV panel controls a thermostatic valve that allows circulation through the collectors when the sun is out and allows the system to drain at night and/or on cloudy days.

 

• This is referred to as a 'passive' solar system, as the water is heated by the sun and is used as heated water. The energy collected is the energy used.

 

• This system was donated and installed by the NC Solar Center in Spring, 2002. "Full Story"

2nd. - The Solar Panels also Known as Photovoltaic (PV) Panels:
 

• Photovoltaic is the process of converting sunlight into electricity by means of a photovoltaic cell.

 

• The Photovoltaic cell is a solid-state device composed of thin layers of semiconductor.

 

• Photovoltaic cells produce direct current(DC) electricity. This is the same type of electricity contained in batteries.

 

• So, PV panels directly produce electricity that can be stored in batteries.

 

• Most appliances are designed to use alternating current (AC)electricity. This is the type of current that comes out of a wall socket.

 

• When AC current is needed, an inverter is added to the photovoltaic system to change the current from DC to AC. This results in a 10-15% energy loss, as it takes some energy to process the conversion.

 

• So, that is how it works here: The PV cells in the PV panels react to sunlight, producing DC electricity. The DC power is sent to the battery bank in the basement. And, when needed, the power is converted to AC to run appliances, lights, water pump, slide projector, etc.

 

• The PV panels are mounted on a four-position wooden frame. They are adjusted 4 times/year to three(3) different horizontal angles: summer at 20 degrees, winter at 50 degrees, and spring/fall at 35 degrees. This maximizes the incoming rays from the sun.

 

• This system was donated and installed by a volunteer core in 1993

3rd. - Wind Turbine (Bergey XL1)
 

• Wind turbines convert the kinetic energy of the wind into usable forms of energy(linear wind energy to rotational force to electricity via magnets, alternator…..).

 

• The Bergey XL1 on top of the 80 foot tower, has a three-blade upwind automatic furling generator.

 

• What is a generator? A generator produces electricity by spinning a magnetic field over a wrap of copper coils. This action produces AC electricity.

 

• So, the wind spins the three(3) blades that you see. This spinning action spins the generator's rotor. The rotor contains the permanent magnets. These magnets provide the magnetic field. The rotating magnetic field interacts with the stationary copper coils on the generator's stator to produce electricity.

 

• The AC electricity generated by the wind turbine is converted to DC electricity by a rectifier bridge circuit located in the generator. The PV and wind turbine outputs are wired to a Bergey charge controller. This controller controls the amount of charging current to the batteries to prevent over charging when the wind and sun provide more energy than the batteries can absorb. This charge controller also improves the efficiency of the wind generator at low wind speeds.

 

• The DC electricity is stored in the batteries.

 

• The generator has an automatic start up at winds of 8 mph but is most efficient at 28 mph. It automatically turns parallel to the wind at 33 mph, in hopes of minimizing damage in high winds.

 

• The Bergey XL1 was funded by a fundraiser and erected by a volunteer core, but the Bergey Windpower Co. has helped with the maintenance of the system.

4th. - The Battery Bank
 

• There are 28 batteries in the battery bank in the basement. The battery bank receives DC electricity from the PV panels and from the converter of the wind turbine generator.

 

• The batteries are Exide GC-145, 6 volt, 245 Amp-Hr golf-cart batteries. They are connected in series strings of four to form a 24 volt storage system.

 

• The 1745 Amp-Hr total battery capacity allows for 3-day/2 night retreats at the Station to run without energy concerns.

How Much Power?

• The PV solar panels produce approximately 18% of the stations daily power requirements.

 

• The wind turbine produces approximately 20% of the station's daily power requirements.

 

• Ideally, when combined, and stored in the battery banks, each day's production of electricity is about 38% of what is needed to run a 3-day/2-night retreat. The rest of the required energy is provided by the battery bank. With a 3-day rest between programs, the battery banks are re-charged to 100% prior to each program.

 

• During programs, electricity is used for: refrigerator, limited use of TV/VCR, lights, and a sump pump and water pump.

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