The subject of this website is the house above with 48 solar panels on roof



This web page briefly covers more technical aspects of the location, design, construct, equipment and operation information for a Passive Solar house situated on Bribie Island , a small island just off the coast 50 kM north of Brisbane, Qld, Australia (Latitude 27 degrees 2 minutes South).

Bribie Island has a sub-tropical environment with a moderate to warm temperature range. The weather parameters for winter are generally dry, cool nights and warm sunny days, (9 to 25 deg C) and, when windy, cool southerly prevailing breezes. For summer, warm north-easterly breezes and a hot, humid, wet season in January/March (22 to 31 deg C). Yearly rainfall is approximately 1600mm.

Water Management

The house has sufficient, roof-fed tank water (52,000 litres) to effectively negate the need to import town water supply. The 1.5 kW pressure pump system is constant flow and powered from the solar system. Simple change-over valving enables transfer to town supply if required. Two, large 'rainwater diverters' ensure first run rain water cleans gutters and pipe work before final entry of rainwater to tanks.

A Beasley 330 litre stainless steel, high pressure, thermosyphon solar hot water system with extremely efficient "all copper" panels with selective coating and low-iron glass covers provides hot water. The HWS is mounted very close to the kitchen and main bathroom (major usage point for frequent hot water supply needs). The HWS solar panels are tilted at 25 degrees, the recommended angle for the house latitude location.

All copper reticulation piping has been oversized in the cold water distribution system and the critical hot water system sections to prevent pressure reduction and reduce flow rates which eliminates noise and water hammer.

All taps are high quality ceramic, part-turn type and equipment using solenoid valves (dish washer/wash machine) have individual water hammer arrestors at machine entry points.

Unlimited (solar powered 1.8 kW pump ) bore water is available for gardens, lawns and garden water features. Town water can feed all bore water reticulation points if required.

All gardens and lawns have reticulated, computer-controlled in-ground/pop-up sprays. Inputs to computer can be timer controlled, soil moisture content and rain water precipitation.

Energy Systems

The house is designed to be electrically totally self-sufficient (if desired) with a photovoltaic powered electrical energy system with large capacity solar storage batteries. The system configuration, as we use it, is in grid/export/battery mode with access to off-peak supply (if required for battery charging, solar hot water system boosting and tumble drying). The grid interactive inverter is programmed to export all power generated in excess of requirements. The current "buy-back" rate for electrical energy for unlimited exported energy here in Qld is currently $0.08/kWH. The system export always generates a credit from Energex and the battary backed design provides seamless, extremely fast (less than 400 milliseconds) transfer between battery and Energex to completely eliminate blackouts and brownouts.

The household electrical requirements are provided by a sophisticated, microprocessor controlled battery/grid tied 4.8 kW inverter (which has up to 10kW short term peak capability for those heavy workshop loads). This inverter is a solar/battery/grid interactive sine wave inverter with in-built battery charger and seamless, fully programmable, energy transfer for import, export and battery charging modes.

The inverter and solar control power panel configuration is designed to provide extreme flexibility, and when programmed to user requirements, is capable of handling various energy management and energy use functions. This permits great flexibility on energy control, use, charging, export, cost management and multiple time-related charges and export rebates. The end result - lower costs to the house owner. If, in the future, electricity supply charges and time-of-use charges go very high (highly likely if our Governments continue on their current path) then the house owner can elect to go entirely 'off-grid', survive comfortably on the solar system and never pay electricity bills again.

A large 48 volt solar battery system (comprised of eight Century-Yuasa Solar, series connected, 875 ampere hour 6 volt solar batteries weighing 135 kG each, totalling approximately 42 kilowatt hours of available energy) enables energy storage from renewables as well as Energex.

Battery storage capacity has been chosen to run the entire household electrical systems (with careful use) for a minimum of two days, without renewables (sunshine) or Energex input, to a maximum of 20% depth of discharge level (ie batteries remain at a minimum of 33.6 kwh available). Selecting this low depth of discharge parameter ensures a long battery life (expected to be well in excess of 15 years). Due to the fact that we have (currently) elected to stay connected to Energex power, we consider the battery reserve capacity is far more than adequate and as we expect to rarely use battery power, the system will enable an exceptionally long battery life.

This convenient Energex connection arrangement can be manually controlled or fully automated based on energy withdrawal from the battery system. Of course, being a seamless, integrated battery operated system means the whole household is on a very effective, uninterruptible power supply (UPS). Already we have witnessed our neighbours suffering from (the ever more frequent) electrical blackouts, and it has been a most satisfying feeling watching their dilemma while we live normally with our uninterrupted, high quality power system.

Our solar system design is very efficient all year round. The bright, sunny, dry winters and the long daylight hours in summer experienced at Bribie Island ensure a reasonably constant harvesting of solar power.

The solar photovoltaic array comprises 48 panels, totalling 3.072 kW, of Unisolar triple-junction, 64 watt amorphous panels. This panel system is capable of supplying up to a theoretical maximum of about 18 kWH per day. Average harvesting over the year is greater than 9 kWH per day.

The Unisolar triple-junction amorphous panels, in contradistinction to poly-crystalline and mono-crystalline panels, exhibit excellent shade and cloudy day performance and no degredation of performance or efficiency when hot (particularly important in a warm climate such as experienced on Bribie). The 48 photovoltaic panels, mounted in 12 aluminium array frames are hinged to allow simple, quarterly adjustment to improve seasonal solar energy absorption efficiency if desired. Each six panels are series wired for a nominal output of 72 Volts, and the 8 groups of panels are parallel fed into an Outback MX-60 Maximum Power Point Tracking (MPPT) Regulator with a nominal output at 48 volts. The Unisolar panels have a 20 year guarantee (which essentially means an unlimited life) thus equipping the house for a lifetime of free, silent energy production. The panel support system permits easy access for cleaning and servicing.

Extra large (70 square mm) cables have been used to reduce voltage drop between panels and Inverter Plant Room. The cables have been tightly strapped together to reduce inductive reactance and substantial metal oxide varistors (MOV's) along with careful earthing systems have been installed to reduce voltage spikes and surges from unwanted induced electromagnetic energy disturbances.

A Large, electrical sub-board with sectioned off C-Bus system and comprehensive data/communications patch panels has been centrally located (in Pantry) for ease of access. All household data, video, control and power wiring to each outlet/lighting point is returned to this main sub-board for central control, easy management, modification and fault-finding. Every 240 volt power and lighting circuit is on indivudual Residual Current Device (RCD) safety switches).

An additional (solar system sub-board) has been installed beside the inverter and fitted with relevant circuit breakers, controlled contactors and control circuitry (currently unused) which can be simply brought on-line to alter the system supply/output systems to take advantage of future time charges or other charging parameters dictated by the electricity authorities.

Considerable effort has been put into surge and lightning protection of the complete household wiring and energy system. The suppression design is based on the fact that the area is prone to electrical storms. Distributed earth stakes with large area subterranian ground planes are connected by large cross section, low impedance cabling (yes! these are different to low resistance cables) and are arranged to minimize potential differences between the grounded parts of the energy system. Ground distribution over a large area ensures low impedance to earth. Low impedance earthing systems are essential for effective lightning protection as lightning discharge high current components consist of large, fast risetime, very high frequency, pulses of energy.

A large number of Metal Oxide Varistors (MOV) on the Direct Current (DC) circuit components and combination MOV/gas discharge surge suppressors on mains Alternating Current (AC) circuits assist in individual circuit over-voltage protection. A large number of MOV/gas discharge suppression units are distributed throughout the entire AC electrical system reticulation. The metal shed housing the solar equipment is individually earthed via a 70mm square cable to a large ground plane to provide excellent earthing/shielding.

The house electrical wiring control system is designed around the Clipsal/Schneider C-Bus computerized "smart" Energy Management and Lighting Control system and the associated computerised Homeminder system. These intelligent systems have fully programmable lighting, security, control, monitoring and renewable energy data recording capability.

The C-Bus system provides appropriate dimming, energy management, temperature, light level and other sensor control and controlled system management and lighting based on programming, activity and learning. Integrated with the C-Bus system are remote control (hand-held infra red controls), and if required, telephone control and computer control via web-based systems, fully programmable audio, video, RF, data and communications systems and wiring.

The Homeminder system, which is integrated into the C-Bus system, provides comprehensive control to whatever level you desire. The system is able to control security, fire warning, irrigation, home appliance and fittings monitoring, temperature, moisture level, data recording capability and has the capability to control digital, voice activated and associated telephone systems control and infra-red remote devices if desired.

Spending a lot of money on renewables energy systems would be foolish without a corresponding effort to utilize modern, low energy, ultra-efficient appliances and lighting. Our desire is to have a relatively "normal" electrical household so we ensured the house is fully equipped with the most energy efficient household appliances available.

All lighting is low energy (mainly by highly efficient flourescent and LED fittings). These are individually and intelligently controlled to conserve energy. The low energy design and lighting ambience has been carefully designed with emphasis on reduced glare, indirect lighting, task lighting and mood control. Many lights are dimmer controlled to minimize energy consumption, provide correct display ambience and to selectively reduce light output during midnight to dawn periods.

The C-Bus and Homeminder systems are able to detect temperature and light level from appropriate sensors (if required), and automatically drop into security or presence detection mode depending on occupancy. In presence mode, the combination infra red and ultrasonic presence/movement detectors do such things as automatically dim up lights when you walk into a hallway, and dim down then switch off lights as you pass out of the hallway. External blinds may be manually controlled or automatically programmed to lower when early morning sunshine irradiates the eastern windows of the house, then automatically raise after the sunshine no longer shines on these windows. Guest room toilet light automatically operates during dark hours and the odour vacuum exhaust fan (which exhaust directly through the toilet bowl area) automatically activates when this room is entered and has a time-delayed switch off after exiting room. The main en-suite toilet also has the toilet exhaust system installed.

General Technical Data

Other important design specifications/criteria selected for the house design are:

1. 32 mpa concrete slab (negligible cracking and impervious to termite penetration)

2. Termite resistant structural design has 75mm clear exposed concrete around complete perimeter, termi-mesh where required on floor penetrations and keyed joints. ALL timber structural and roofing truss components are selected termite resistant/treated timber.

3. Extra strong, cyclone proof design and tie-down detail.

4. Low maintenance design, natural finishes and reduced painting requirements.

5. External (under eaves & covered walkways) sheeting designed to reduce external "nooks and crannies" to limit insect/spider habitat and ease cleaning chores.

6. House design has distinct resting, working, relaxing, entertainment and visitor accommodation areas with appropriate color and finishes to promote the differences between these areas.

7. Three bedrooms, two bathrooms, two private "rest" rooms, both fitted with bidets and efficient odour vacuum toilet bowl ventilation systems.

8. Large study with integrated digital, video, LAN wiring and permanent data connection to C-Bus, Homeminder and C-Touch systems. Study has in-built bookshelves, computer desks and lockable filing cabinets.

9. Very large walk-in pantry/wine cellar with all surrounding walls constructed with rammed earth to provide a constant, cool temperature through massive thermal inertia.

10. Very large laundry/sewing room with large storage areas and off-peak availability for tumble dryer.

11. Both sound and thermal insulation combined with natural materials to provide a quiet, thermally stable environment.

12. Most ventilation glazing is of "louvre" type, thus permitting extraordinary breeze control and inclement weather control (ie, louvres can remain open in summer for breeze control yet prevent rain ingress).

13. Installation of a large (1200 mm diameter), roof mounted, slow-revving fan that on those few hot days each year, can be computer and temperature controlled to start up and create a pleasant, cool and healthy air change throughout living areas. The fan is mounted in the ceiling and exhausts air above the roof line. This very low wattage fan can completely change the air in the house each 40 seconds.

14. All exhaust fans exhaust above roof line.

15. Wide eaves for weather protection (the northern side eaves width designed for passive solar calculated requirements).

16. Ability to "see the sky" from all living areas - a relaxing and philosophical point of interest (based on our ancestors mode of living?).

17. Open plan living with designed spatial effects to open up the living areas that have a bright, natural and very peaceful ambience.

Floor Plan (house only)

House Plan


Much reading and access to the Internet has been underway for some years to build our knowledge base to ensure a well designed and extraordinarily comfortable house. Some of the books and magazines we found helpful (in no particular order) are:

ReNew Magazine ( ReNew ), an excellent, Australian, quarterly magazine touching on technologies for a sustainable future.

Solar Progress, official journal of the Australian Solar Council

Solar Technology Designers Catalogue, published by The Universality of the Sun ( Unisun ). This catalogue, authored by Christopher Darker, has great design data, hints, how-to articles and a lot of realistic, commonsense advice.

Warm House - Cool House by Nick Hollo. Inspirational designs for low-energy housing. An interesting collection of ideas and projects throughout Australia. ISBN 0 947277 22 6

Renewable Energy. Energy Efficient Building Design Resource Book, Certificate IV text book in Renewable Energy Technologies. Brisbane Institute of TAFE. ISBN 1 876880 03 1

Solar Dwelling Design Concepts, ISBN 0-8473-1574-6

Fred & Jeanette Birkbeck


Note: Banner at top of page displays an aerial photograph of our passive solar house overlooking a deep-water canal that has direct access to the Pacific Ocean.