significant, collective ramp events
There were 12,000+ solar PV systems installed in Canberra by the end of 2012. Through cooperation with ActewAGL, our local distributor, we've been provide the postcode and rated capacity of these installations.
We've also been able to collect data from 200+ sites in Canberra which have reported their power output publicly, drawing from a variety of available web servers.
Using these 200+ sites, Sonya searched through images of their collective power output (meaning all 200+ sites added together) searching for times when the collective power output from these PV systems changed very suddenly - this is termed a ramp event.
what's a ramp event?
I've addressed this topic a few other times on this webpage (see here or here), but I'm a nice guy, so I'll do it again. A ramp event is a term used to describe a situation where the power output from a PV system experiences a large change very suddenly. A positive ramp event implies the power output changes from a low value to a high one, and a negative ramp event is the opposite.
In our case, Sonya was searching for ramp events where all the PV systems experienced a ramp at approximately the same time (we term these 'collective ramp events'). These types of events are important, because they indicate that all the PV systems in the region (12,000+) experience the same change - and that means big changes in the supply-demand balance of the electrical grid.
This type of event doesn't matter unless there is a high penetration of solar PV systems in a given region, meaning that more than 20% of the electricity is being supplied by the collective generation of all the installed systems. It just so happens that in the ACT, we have a 90% Renewable Energy target (one of the best in the world!). As a result, we are installing several large solar farms (20MW plant at Royalla just opened a few months ago) and the uptake of rooftop PV continues to steadily increase.
So if there is anywhere in the world where solar forecasts matter, it's likely that Canberra is it.
Now I can only say 'likely' because this whole electricity grid thing is really complicated and we simply don't have enough information about the location/arrangement of the PV systems in Canberra to make a final conclusion. But that's part of what today's presentation is about - working with ActewAGL to make sure the continued integration of heaps of solar in the Territory can continue.
what did we find out?
Over a two year period, Sonya identified 19 positive and 16 negative significant, collective PV ramp events in the ACT. She then categorised the weather events that lead to these events, which are presented in the following table: