On the 22nd of June, 2009, the Renewable Remote Power Generation Program (RRPGP) was closed to all Australian States and Territories except Western Australia. Households, businesses and community buildings in WA are still eligible for receiving a 50% rebate for all their solar Off-Grid solar energy installations. This is a perfect opportunity for remote buildings not close to the main grid to capitalise on remote renewable energy incentives, including both solar and wind energy, implemented by The Department of the Environment, Water, Heritage and the Arts (DEWHA). There is no telling when the RRPGP could be completely pulled, so all encouragement is being given for eligible people in WA to act now.
This article will help you conduct an analysis into knowing how much energy you’ll need – critical to the design of your stand alone system.
If you are building a house and want to implement a remote power system you will first need to carefully choose your appliances before selecting the appropriate solar or wind system. Some commonsense investments include using energy saving fluorescent light bulbs and buying a fridge with a high quality energy rating rather than an energy-intensive one. Studying the energy rating on all necessary appliances in the home (TV’s, radios, computers, etc…) to ensure they are energy efficient is another important step. Some high load appliances, such as electric heaters and luxury items, can be forgone altogether to ensure costs are minimised. Once all appliances have been selected, a wise move is to put them into an Energy Budget Table, as per the example below. This will greatly assist in gaining an understanding of what type of system is suitable for your energy needs:
Daily watt hours
Sometimes it is better to have larger appliances powered by a source, such as fuel, other than your solar panels. Refrigeration is a good example. Normally electric refrigerators are the largest single load on the typical property and switching to a propane refrigerator can be a viable alternative. Electricity needed to provide space heating is also fairly costly and sources such as passive solar, wood, or heat/propane furnaces are all much more practical. Similarly many remote houses have electric well-pumps which bear a heavy energy load. Traditional method such as wind-powered mechanical pumps can be considered in these circumstances. It again comes down to behavior. When a task requires you to use either a 1,200 watt dryer or a towel, both options energy consumption should be considered.
Load Profile (variation of the electrical load over time)
Once your total load has been tallied you can graph your load profile to deduce your daily electricity profile. Hours in the day have been plotted along the x axis and loads have been plotted along the y axis.
Your load profile will be able to identify what your peak load and base load will be. Your Peak load will determine the most electricity you will need at a certain time while your base load is the constant energy stream that you will need for things like fridge and lights. To lower your peak load you can stagger the use of your devices to ensure that only one high-energy using activity is occurring at one time – this is known as Load Shifting. Similarly you could sacrifice the plasma TV screen for something more efficient which would reduce the overall load, meaning a smaller, less costly solar energy system.
Although your battery will store electricity in a Direct Current (DC) most household appliances use an Alternating Current (AC) and therefore require an inverter to convert this power. Some power is lost during this conversion and to be safe a lot of remote-power literature recommends designers take into account an average of 85% inverter efficiency. Therefore the inverter wattage should be 15% higher than your largest peak load.
Let’s imagine that a house is operating lights (60 W) and a stereo system (40W) a washing machine (500W) and a deep well pump (1400), you will need to take all of these elements into account to select an inverter capable of 60 + 40 + 500 + 1400 = 2000 Watts. The inverter wattage must be 15% higher, totaling to 2300 Watts than the largest potential load. It is therefore more economical to employ energy intensive activities to reduce the peak load.
Remember to keep energy production down to a minimum as it is costly to use more energy than you need so construct your Renewable Energy system wisely.
Solar Choice Pty Ltd
© 2009 Solar Choice Pty Ltd
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