Solar overtakes brown coal in mid-day power, and keeps prices down

On Monday we noted how solar is now emerging as the biggest power source in the South Australia grid during the middle of the day, heralding the next phase of that state’s transition towards 100 per cent renewables.

Now we have noticed another new and significant milestone. Across the whole of the National Electricity Market, solar is overtaking brown coal in capacity output in those hours in the middle of the day – and keeping prices down as well.

This graph above from OpenNem shows that in each of the last seven days across the NEM (which includes all states apart from WA and the Northern Territory), solar was producing more between the hours of 10am and 2pm than the country’s huge brown coal generators in Victoria.

During these hours, solar was the second biggest contributor to the national grid behind black coal. Wind vied with brown coal for second place, while gas was relegated to just a few percentage points when solar was at its peak.

Australia remains stubbornly dominated by fossil fuels, which continues to account for more than 80 per cent of total generation, but the share of solar and other renewables will grow quickly in coming years as another 5-6GW of large scale wind and solar is added to the grid, and the uptake of rooftop solar continues apace.

Apart from grabbing a large share of the generation at key periods, solar was keeping the prices down in every state.

The average price of wholesale electricity when rooftop solar was producing was around $50/MWh, and about $52/MWh for utility scale solar. The average price for brown coal in Victoria was 25 per cent higher, and for black coal in other states was 40 per cent higher than the grid-wide average for solar.

In Victoria, the average wholesale price for solar was $45/MWh to $52/MWh, compared to $62/MWh for brown coal; and in South Australia it also averaged between $45/MWh (rooftop solar) and $51/MWh (utility scale solar), compared to $78/MWh for combined cycle gas and $116/MWh for open cycle gas.

Even in NSW, the average wholesale price when solar was produced ranged from $55-57/MWh, compared to $68/MWh for black coal, and in Queensland it was $63-$64/MWh for solar compared to $72 for coal.