In conjunction with this larger post (including animation) looking into what happened in the Queensland region on “sizzling Saturday” (14th January 2017), I’ve powered up NEM-Review v6 to create the following chart:
It’s not 100% accurate (as there are other factors to consider) but adding Rooftop PV (AEMO estimate*) to the Scheduled Demand for the region provides, in aggregate, a view of approximately what total consumption has been across the three days shown (Friday 13th, Saturday 14th and Sunday 15th).
* with respect to the AEMO estimates, see my prior note about the opacity of small-scale PV. Thankfully with AEMO data we’re able to start publishing about these insights.
Ten years ago, “Consumption” and “Scheduled Demand” might have been pretty much the same thing – but increasingly the two are diverging, and both need to be kept in mind to understand where the electricity system is headed. This chart is fairly typical of what we’re seeing – and is not unique to Queensland, either. What it shows is two related things:
#1) The batch of rooftop solar PV currently installed has definitely reduced peak demand
This is very apparent in the chart above – which is just a random example. On Friday 13th January, for instance, we can clearly see that the demand would have peaked above 9,500MW had it not been for rooftop solar PV. Similarly, on Saturday 14th January, the demand would have peaked above 9,000MW – and so on…
#2) … however more of the same won’t deliver more benefit (and is likely to bring its own challenges)
As per the second note on the chart, however, because the time of peak demand has shifted to late afternoon (when rooftop solar PV injections are waning) the addition of more solar panels won’t deliver any more benefit to the market in terms of reduction of peak demand.
Indeed, because of the “duck curve” phenomenon we’ve spoken about previously on WattClarity, it will come with its own challenges.
Don’t take this as a reason to stop building solar PV – however please do:
i. Stop promoting it on the basis that more will reduce peak demand more; and
ii. Understand some of the challenges that come with it.
** UPDATE at 17:30
Two of our valued readers has let me know that the above is not that clear – for which I apologise. Both readers had two particularly useful points to make – hence the update here:
#1) Assuming north facing
When I make the comment that “more solar PV won’t reduce peak demand more”, what was I left unstated was the “… if it’s more of the same”. With this I particularly mean the current incentive structure geared towards a kWh harvest, which provides the (quite logical) motivation for people to install PV on north-facing rooftops. As seen in the chart above, this has had a great effect on reducing demand in the middle of the day – however that’s not where the peak demand is any more (see point 2).
If the incentive were to change, say, to promote west-facing panels (for at least a reasonable proportion of new installs) then we would see the afternoon peak reduce more – however it would be at a “cost” to the owner of a lower kWh harvest.
Hence the question why would they do this? Not too many are purely altruistic.
#2) It varies by location
Another telling comment was made that the details are buried in the distribution system – down at zone substation level, or even lower at the feeders.
We’re working on data sets down at that level that might help with that puzzle…