Home solar update after seven years

The rooftop PV system we installed seven years ago has just passed another good round number – 16 000 KWh – having produced 4 000 KWh since my last update, in September 2016.

The daily average in that period is therefore 5.9 KWh/day, a little lower than the average of the first five years.  The drop in output is so small that it’s not really worth worrying about but three explanations come to mind, and all may have contributed to it:

  • We don’t bother cleaning the panels, so full-sun output may have dropped;
  • Our trees have kept on growing, so the panels may be shaded for longer, especially in winter;
  • The period we are considering includes two full Wet seasons but not quite two full Dry seasons (the month-by-month variation is shown here).

How much money are we saving now?

Continue reading “Home solar update after seven years”

Are rainwater tanks useful in Townsville?

Townsville’s ongoing drought has encouraged many of us, especially the keen gardeners, to think seriously about bores, grey water systems and rainwater tanks. This post attempts to arrive at a credible answer to the first question we must ask about tanks: are they even useful?

We have been hearing from two schools of thought on the question for as long as we have been in Townsville, more than 25 years: “Yes, of course!” and “No! The dry season is so long and so dry that no tank will last through it.” One group must be wrong, and the only way to find out is to crunch a few numbers. Continue reading “Are rainwater tanks useful in Townsville?”

Renewable energy update

Green Path tries to keep up with what’s happening in the renewable energy sphere, since it’s so important to our battle against global warming, but so much is happening that we don’t often pause to take stock. Fortunately, the Climate Council has done that for us, producing a report, Fully Charged: Renewables and Storage Powering Australia. 

Its key points are:

  • The cost of lithium-ion batteries has fallen by 80% since 2010. Costs are expected to halve again by 2025 (under 7 years).
  • 6,750 new household batteries were installed in 2016. The market is predicted to have tripled in size in 2017, with over 20,000 new installations.
  • Renewable energy now represents 16% of Australia’s electricity generation.
  • VIC, QLD and the NT are also investing in grid scale battery storage technology.
  • Federal, QLD and TAS governments are also considering developing pumped hydro projects.
  • The Australian electricity grid (NEM) and old fossil fuelled power stations are increasingly vulnerable to worsening extreme weather events, particularly as these power stations age.
  • More than 50% of Australia’s coal fleet will be over 40 years old by 2030.
  • Australia could reach 50% renewables by 2030 without significant new energy storage.

That is (nearly) all very good news, of course, but we need to keep it in perspective: 50% by 2030 is good but, globally, we need to reach zero carbon emissions before 2050 to avoid the worst of climate change, so there is still much more to be done. Continue reading “Renewable energy update”