Solar power systems in northern Australia

I recently installed a solar power system & found it difficult to find information regarding the top third of the Australian continent. Almost all the information online relates to our largest capital cities, which are of course all located in the bottom third of the continent.  Why does this matter? Because once you are north of the Tropic of Capricorn, the angle of the sun is significantly different, there is relatively little difference in summer/winter day length, and the climate is very different (not just hotter; greater humidity and torrential rain on sun-heated panels etc means panels have a tougher time of it).  So much of what applies to southern solar power systems does not transfer automatically to northern Australia.

Through much digging around these are the solar power issues I came across; explained in lay-person’s terms. Bear in mind that of course this technology is evolving, so some issues will presumably improve, eg performance in temperatures about 25 degrees:

  • The very first thing to consider, but which I didn’t see mentioned anywhere, is the condition of the roof you want to put the panels onto. Good quality solar panels should last for years. Don’t stick them onto a roof that’s rusty. Yes seems like a no-brainer; but I asked about this and yes, people have been bolting long-life solar panels to rusty rooves.  Including one so rusty the installer fell through the roof….
  • In southern Australia the best position for solar panels, all things being equal, is a north-facing roof. And the further south you are, the more important it becomes to have the panels tilted up to the optimum pitch towards the sun.
  • In northern Australia (top third – or at least, above the Tropic of Capricorn), the sun is more directly overhead, even relatively so, during winter.  On a fairly flat roof, panels on a south-facing roof are fine. I only found this out with a lot of poking around the internet. This 5kw system was connected after noon today, and generated 12kw in less than 5 hours.
  • In cyclone-prone regions it’s smart to lie the panels flat on the roof, rather than angling them up on brackets (like wind-catching sails) towards the sun.  From what I read, it’s also standard to locate them at least 60cm below the roofline, to help avoid them being blown off.
  • Solar panels do need a hose down and a gentle broom over them every now and then, if dusty and/or leafy, to keep them performing to the max.  Obviously the flatter the roof the easier & safer this is to do; but the flatter the panels are lying, the more dust will settle.
  • Many people say solar panels have made their house significantly cooler. Makes sense when you think about it – they not only shade the roof, they absorb the sun’s energy, turn it into power and send it away.  So if you have a choice, siting solar panels over the hottest room in the house – or on the roof of a very hot garage – can have useful side benefits.
  • Solar panels need the sun to work, so the more hours of daylight there are, the more power can be generated. However – solar panel performance drops when it’s very hot; with most panels, this being above 25 degrees.  Not what you’d call “hot” in Townsville, with our average mid-winter maximum temperature being 26 degrees! So oddly enough, apparently in Townsville spring months are the best performing – when the temperatures haven’t reached the highest levels but the days are lengthening.  There are variations between brands and particular types of panels. This is where local knowledge of what panels work best, is vital.
  • Shade. Solar panels need direct sunlight to maximise energy creation.  Check your roof carefully to ascertain if there is shade at any time of the day, and how it changes throughout the year.  Solar panels are linked together in ‘strings’ and if one panel is shaded then performance of the whole string suffers.  This is another issue that I think may vary between panel brands/construction types; and with luck, may not be such an issue in future.
  • Cloud. Of course solar power systems don’t perform as well when it is cloudy. So get to know your typical cloud pattern. For example, if you’re choosing between locating a solar system on an east or west roof, and you’re in a region that often has a build up of clouds by mid afternoon whereas mornings are usually sunny, obviously the east-facing roof is the smartest choice. And vice versa.
  • Haze. The installer mentioned to me that for some obscure reason, one day will turn out to be exceptionally good for generating power compared to another day which appeared identical. I presume this is due to haze – whether smoke, dust or moisture in the air; deflecting sunlight.  Not something you can really work around, but should be born in mind as if it’s a frequent problem it’d have a noticeable affect on power generating performance.

Lastly, and this is a tip for the future:

  • At present many people are lucky enough to be being paid more for the solar generated power they’re exporting back to the electrical grid, than they are paying their electricity provider for power used. In this situation, it’s best to maximum household power usage when the solar system is not generating any power (i.e. at night); to maximise the amount of power you’re selling to the electricity supplier. HOWEVER at some point in the future, the cost per kilowatt of power paid to the electricity supplier will be greater than what they’re paying households/businesses for solar generated power; presuming they don’t raise the per kilowatt purchase price.  When this pricing change occurs, it will be best to use as much of the power you’re generating yourself in preference to using the higher-priced power supplied by the electricity company.  Peak power generating time in most areas is during the afternoon, when the sun is in the western hemisphere. So solar systems best sited to generate power during the afternoon – eg perhaps on west-facing rooves – will presumably be more economic at some point in the future.

If anyone has any other thoughts, I’m all ears. There’s a truckload of technical solar power system information on Whirlpool forums – but as mentioned, the vast majority applies to southern Australian conditions, and I didn’t find a simple list relating to solar panel system location factors to consider, anywhere.

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