GEI Insight: Economics of Solar Energy – Duck Curves

Economics of Solar Energy

Solar energy output and the demand for solar energy have a nearly inverse relationship.

Think about it – the time when solar production is high (midday) is when we don’t need power for lights. However, when solar production is low (evening), we start turning on all the lights in the house!

The rise in solar energy use, partially attributed to China’s disruption of the solar market that brought down the price of solar panels, diversified and restructured the world’s energy portfolio.

However, there’s another challenge for solar power – grid distribution, meaning, how to efficiently use all the solar energy captured, evenly throughout the day.

The Duck Curve

This ‘fill in the gap’ solution is creating a phenomenon is known as a ‘Duck Curve’ – figure 1.

Figure 1: California’s Energy Consumption and Solar Output

The curve that resembles a duck is the ‘net load’ (orange line), which comprises the supply of energy generated by all sources excluding solar.

As you can see, the net load rises in the morning (duck tail), slopes down in the afternoon (duck’s back) and increases in the evening (duck head). Now can you see the duck?

The gray line comprises only solar energy output, and as we already know, it’s the opposite of our duck curve.

Finally, is the blue line, the total load or total supply of energy produced by all sources.

The 2 Problems of the Duck Curve

This mismatch between supply and distribution leads to two energy and infrastructure-related problems – which in turn cause the ‘duck curve’ phenomenon to actually grow, see figure 5.