There are a number of factors that can have a big impact on whether solar panels will work out for you financially. You should consider these carefully before you decide whether or not to go ahead.
1. Average Daily Sunlight
The average number of hours of sunlight your region receives per day is of course the biggest factor in determining how much electricity you’ll generate from solar panels. While solar panels can still produce electricity on cloudy days, they are at their most efficient on sunny days.
Most Australian states receive average or above average levels of sunlight, however if you live in Victoria or Tasmania, your level of sunlight will be slightly below average. The map below shows you how daily sunlight hours vary across Australia.
Average daily sunlight hours in Australia. Courtesy of the Bureau of Meteorology.
Our Solar Panels Calculator has the average daily sunlight statistics built in for the major cities in Australia, taking the guesswork out of the equation for you.
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2. Average Temperature
You might think that the hotter the region, the more electricity your solar panels will produce. Well that’s not always the case. As the air temperature goes above 25 degrees Celsius, solar panels actually start to lose efficiency. In general, most solar panels will work quite well in most of our main cities, however if you live in areas with extreme temperatures (for example outback Australia), you’ll need to select panels that can cope with those extremes.
We cover what types of panels are suitable for extreme temperatures in our section on selecting the right solar PV system.
3. Your Roof
Solar panels work best when they are facing north, as this is where the sun is for most of the day. If you don’t have a north-facing aspect on your roof, you should face your panels west. This is because the west receives afternoon and evening sun, which is when electricity rates are at their highest – so producing more electricity at that time will save you more money. If west is not an option then face them east, so you’ll at least get the morning sun.
Solar panels should also be positioned at an angle of around 20-30 degrees relative to the ground. This is to make sure that the panels get a “direct hit” from the sun, which will help maximise the amount of power they generate. Most sloping roofs in Australia are already at an angle of 20-30 degrees, so in these cases the panels can be attached straight onto the roof.
If your roof is flat, you’ll need to install a mounting bracket that can hold your panels in position at an angle of 20-30 degrees. (see image below). Mounting brackets are an additional installation cost, and you may also need council approval before installing one.
Solar panels attached to a mounting bracket on a flat roof
Do you have trees or adjoining buildings that block sunlight from hitting your roof? If so, then your solar panels may not produce a lot of electricity. When choosing a direction to point your solar panels in, make sure that there is no shade that blocks sunlight from reaching the panels.