Grong Grong Solar Farm is at the far end of the commissioning phase with Essential Energy and approaching ‘practical completion’ under the construction contract with Watters Electrical.
During this phase we are closely monitoring the solar farm and are working with the inverter supplier Fimer and our contractor Watters Electrical to calibrate the settings to achieve full solar farm performance.
We can report that when the solar farm is operating, it generates broadly as expected. Good news so far!
Generation Data
Generation data is not easy to interpret, as a number of factors come together to determine generation:
- technical plant performance, i.e. how well the solar farm has been designed and built and how well its components works
- so-called ‘economic curtailment’, where we switch off the solar farm where the market price for electricity falls below -$40 per MWh
- weather data (with the prime influence of solar irradiance, but also temperature).
Technical plant performance
We have had two multi day outages, where the solar farm has shut down unexpectedly. Once it was determined why the solar farm shut down, inverter settings were adjusted to reduce the potential of further shutdowns.
Economic curtailment
In second half of August and in September, we saw a significant number of 5-minute intervals (the periods during which the price is set in the National Electricity Market) below -$40, which is our current setpoint for shutting down the solar farm.
Weather impact
Solar farms perform the best when levels of irradiance (sunshine) are high, and temperatures are low. The modelling software PVSyst uses a specific dataset to provide us with forecast generation, but actual weather data has a significant impact.
Overall picture
Solar farm generation exceeded forecast generation in June and July. The solar farm generated less in August and September than its potential due to the outages mentioned above and also economic curtailment in response to negative prices.
The graph above shows:
- Forecast Generation – based on PV Syst model included as a benchmark for context
- Actual Exports – actual solar farm generation and supply into the local grid
- Actual Plus Allowances – actual exports plus ‘allowances’ for outages and economic curtailment to show what the solar farm would have generated if it were to generate at its potential
The allowances are an estimate of how much generation would have occurred if the solar farm was operating at times that it wasn’t. These estimates were performed by director Jonathan Prendergast, based on the seasonal / monthly forecast average generation, nearby days of solar generation and solar irradiance data from the solar farm.
July Generation
The graph below shows July daily generation. July saw no outages and there were high prices and, accordingly, no economic curtailment.
Economic curtailment in August and September
The graph below shows the daily average wholesale prices between 8am and 4pm. It also shows the average for three 6-week periods, to show these three stark periods of high, very low and medium prices.
In July and the first half of August, we saw quite high wholesale prices averaging $133 per MWh. Good news! This was possibly due to high demand during cold weather and lower solar and wind output.
From 17 August milder weather reduced overall demand. At the same time, with sunnier days drove up solar output and wind output returned. This saw the average daytime price drop to $0.9 per MWh!
In consequence, we had to undertake economic curtailment of the solar farm generation.
As it happened, this period coincided with an outage – we did not lose much generation due to the outage as we would have been in economic curtailment in any event. While not an excuse, this was probably quite lucky!
The below graph shows September generation, also with an outage and economic curtailment.
An open community
Grong Grong Solar Farm has raised over $1.9 million of equity funding from ~670 seed and crowd equity investors. Our investors are important stakeholders, and we want to give them the opportunity to continually learn about solar farm solar development, finance and ownership. We will continue to provide data to allow the sharing of our lessons learnt.
You can also see details of the commissioning process in this webpost – https://gronggrongsolarfarm.com.au/grong-grong-solar-farm-commissioning-update/
This update has focused on generation data. We will be in touch in the near future with update on other topics like finance updates and other milestones.
You can also stay up to date by following the Grong Grong Solar Farm Facebook page.