CASE STUDY SYSTEM 2
A
typical family home hybrid wind, diesel & photovoltaic stand-alone system
System design brief
This is a typical home using natural gas (or bottled LP gas)
for all heating and cooking applications. The home would also use a gas boosted
solar hot water system for hot water requirements. There are a range of appliances
used in the home such as a washing machine, a television, an evaporative airconditioner, a computer, various
kitchen appliances, power tools, and lights. The average daily energy use
was calculated to be 6.3 kWh/day in the winter or dry season and 9.6 kWh/day during the summer or wet season, using the information supplied. (see Energy Calculation Worksheet)
System Sizing
The system was sized according to AS4509.2 design guidelines. This process uses
information about the daily load and local conditions to calculate the sizes
of all components in the system. (See System Sizing Worksheet)
System Installation and Specifications
This system was installed in February 2006 and is comprised
of the following major components:
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Photovoltaic Modules and Array Frame
This system has 16 Solarex 77 Watt PV modules, on a pole mounted, tiltable array frame. The peak output from the array is 1232 Watts. The array is tilted at an angle of 45°, to maximise the output performance in winter.
Array Frame and Mounting
The PV array has been pole mounted using two Uni-Rac Series 5004 array mounting systems.
The six inch schedule 40 steel poles were galvanised and have been set in approximately 1.75m deep concrete footings. This has been chosen for a design wind speed of 200km/h. |
Photovoltaic Charge Controller
The solar charge controller ensures the electricity from the array going into the battery bank has the correct voltage or current to charge the batteries. It detects the state of charge of the batteries and decides the appropriate charging regime.
The charge controller is a Plasmatronics PL40 Advanced Solar Charge Controller with a 40A current rating.
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Wind Turbine
The wind trubine is a Westwind 3kW Turbine. It is a 48Vac machine and sits on an 18m tow-up guyed tower. It uses 1.8 m blades, with a swinging tail which is automatically furled in high wind speeds turning the turbine out of the wind. The turning away presents a smaller rotor area to the wind which decreases the speed of the blades.
The wind turbine produces AC electricity which is rectified to DC electricity at a voltage appropriate for charging the batteries or for being fed through the inverter to power the loads of the system. |
Wind Turbine Inductors (Choke)
The three phase AC electricity is sent to the inductors which limit the peak currents that can be generated by the wind turbine in high winds.
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Wind Turbine Controller and Battery Charger
This is a Westwind wind turbine controller,
which uses a dump load for handling excess energy production. This component
also has meters to display battery voltage and wind turbine current
The controller converts the 3 phase AC voltage from the wind turbine into DC voltage as required for correct battery charging. When the battery bank reaches its full charge state, the controller switches the surplus turbine output across the Dump Load Resistor (see below).
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Wind Turbine Dump Load
This is a resistive load designed to dissipate the excess power generated by the wind turbine when the batteries are fully charged. It can dissipate up to 3 kW of power.
This dumps excess energy from the wind turbine. When energy is dumped this is an ideal time to use appliances such as washing machines and vacuum cleaners which use a lot of energy. |
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Diesel Generator
The system has a backup 5kVA diesel genset which is manually started. The operator decides when to start the gen set. One condition is low battery voltage. The other condition is when large loads are expected, i.e. welding.
The engine is a Robin DY41D and the generator is a 5kVA unit from Modra Engineering |
Inverter
The inverter changes the DC electricity from the battery bank and solar array to AC electricity for use with standard appliances like televisions, VCRs, refrigerators, electric drills, other power tools and kitchen appliances.
The inverter is a Power Solutions Australia, RAP-3-48-1, Generator Interactive Sinewave Inverter, 3kW - 48V. |
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Battery Bank
The battery bank has 8 EXIDE Energystore 6RP1080 flooded lead acid batteries connected in series which produces a 48
Vdc battery bank with a total rated capacity of 1080Ah at the C100 rate. The battery bank has been designed for 3 days storage (based on the summer load of 9.6kWh/day) and a 60% maximum depth of discharge.
The battery bank is housed in a 1.5m x 3m garden shed that has extra ventilation installed to meet the current standards for battery installations.
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DC Switchboard
This houses all of the DC metering and
circuit breakers for the system. For the purposes of the display this box also houses meters to show energy flow through the system. The metering displays include:
PV current after the controller (into the batteries), PV voltage and current before the controller.
Wind turbine current into the batteries and the wind turbine current through the dump load.
Inverter DC current, battery DC current and battery voltage.
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AC Switchboard
The 240 Vac wiring has been
done to the relevant Australian Standards (i.e. AS 3000). The switchboard has
a safety switch (earth leakage detector), mains isolator switch, a circuit
breaker for power points and a circuit breaker for the lights. |
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System Loads
This display system has some loads such as an air conditioner, refrigerator, lights and water pump. It also has programmable loads that allow the system to be operated as it has been designed. It shows how much energy the system actually delivers and allows the system performance to be analysed. |
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This system is fully monitored for display and educational purposes. This adds to total system cost and would normally not be done.
Current and historical performance data can be found here.
Cabling
The system uses cabling appropriate for the current capacity
of components.
Battery cabling - uses 32 mm2 cable
Inverter cabling - uses 25 mm2 cable |
Automated data acquisition systems monitor the performance of this RE display system. A current snapshot of weather conditions and power flows in system 2 at the display is shown in the dials below (these dials are updated every 10 minutes - hit refresh). More detailed system performance data can be displayed and downloaded - click here.
Current conditions at the RISE Outdoor Test Area
Current System 2 Power Flows (updated every 10 minutes)
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System costs
The following table contains the costs of the
various system components as at 2005. These costs are
based on the recommended retail prices of the equipment (or
similar) from the Western Australian suppliers. All prices include GST.
| Unit |
Est. 2005 cost per unit |
Total component cost |
- 1.232kW PV Array (multi-crystalline silicon)
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$889 |
$14,230 |
- Plasmatronics PL40 advanced solar charge controller
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$429 |
- Array frame, hardware and foundations
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$5100 |
- 3 kW Westwind Turbine - including controller,
18 m tower and all hardware except for cabling
from tower to controller and concrete for
foundations etc.
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$ 24,000 |
- PSA RAP-3-48-1 3kW generator interactive sinewave inverter
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$8,000 |
- 8 EXIDE Energystore 6RP1080 flooded lead acid batteries
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$1,420 |
$11,368 |
- EXIDE 24VDC automatic watering system for battery bank
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$968 |
- Garden shed with appropriate vents, including concrete floor
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$1,182 |
- Electrical hardware including switchboards, cabling, metering and miscellaneous parts
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$9,048 |
Total System Cost |
$74,325 |
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