Stand Alone Power Systems
A Stand Alone Power System (SPS) generates electricity independent from the public grid.
While the outlay for a Stand Alone Power System is initially high it can certainly beat in many cases the cost of getting connected to the grid on properties with long distances from existing powerlines to the actual house.
Other uses are for motor homes, boats, small holiday houses etc.
In the majority of cases the electricity is generated with solar PV panels. However, if other renewable energy sources are plentifully available, wind and hydro power can be utilized.
The electricity generated is stored in batteries. It is vital in the planning stages to support your system designer with information which reflects your day to day electricity usage patterns.
What system is right for me? The approach ‘I want a one fits all average’ will lead to either an undersized system, using large amounts of fuel for a generator back up, where you spend again money later in extending it or over sizing the system where your batteries are not cycled often enough and as a result will cost you a lot more than it could have if it were sized correctly.
The same way as you would spend time and care to find the right size and comfort level in shoes we would encourage you to apply in finding the right system for you.
Below is an example in how you can help us to determine your daily electricity requirements. The loads shown are a guide only. Please be a sleuth and look at what you are using in your current dwelling and add it to the list. If you don’t know what your appliance’s Wattage is then look at the tag on the appliance or send photos for each tag.
|QTY||APPLIANCE||Watts per item||Hours used per day|
|4||Compact Fluorescent Bulbs (CFL)||10 – 20||5|
|2||Fluorescent Lights (tubes) 1200mm||40||2|
|1||LED 50 cm TV (colour)||60||3|
|1||LED 100 cm TV (colour)||125||3|
|1||Colour or laser printer||20 – 500||0.25|
|1||Mobile phone charger||5||2|
|1||Refrigerator||70 – 300||12|
|1||Freezer||70 – 300||12|
|3||Pedestal fans or ceiling fans (in summer)||60 -80||3|
|1||Microwave||800 – 1500||0.25|
|1||Electric kettle||1500 – 2400||0.25|
|1||Blender||150 – 350||0.25|
|1||Sewing machine||50 – 100||0.25|
|1||Power tools||300 – 1500||0.25|
|1||1 HP water pump||750||0.10|
As there is not always sunshine available we recommend the battery to be sized for 3-5 days autonomy (meaning cloudy days where your batteries could not be re-charged by sunlight).
This is a decision to carefully consider if you wish to cover those days with a larger battery bank or by a generator (note a generator can guzzle a lot of fuel if required to cover a day’s worth of electricity usage) or a combination of both.
|Days of Autonomy required||With extended battery only||With Generator only||Combination of generator and extended battery|
Going one step further, now it is time to consider where the solar panels would be mounted. The most cost effective solution would be an existing structure like a roof which is in close proximity to where the batteries and all switch gear are stored. In the ideal scenario the roof would face North and the pitch of the roof would have latitude angle (27.5° for Brisbane), shade free.
However West and East facing roofs are also good contenders and lower roof pitches are suitable as well, but may need tilt framing if very low (recommended for roof pitches under 10°). Your designer will discuss with you the differing outputs compared to ideal conditions.
|Roof mounted array||√|
|Ground mounted array||N/A|
|Pole mounted array||N/A|
|Pitch of the roof||5°|
|Material the roof is covered with||Corrugated Iron|
|Notes: require tilt frames, not enough space on one roof|