2018 has become a record year for global solar deployment issues. Research firm GTM Research expects solar-powered installed capacity in 2018 to be the same as the total installed solar capacity before 2013. Of course, from a short to medium term, solar power generation has good prospects. However, in the long run, the prospects for solar energy are still unclear. As the penetration of solar power increases, the value of additional solar energy on the grid decreases.These have been demonstrated through research on California's "Duck Curve" grid data, which is needed to reduce solar power generation when solar power exceeds the capacity that the grid can support.

If the marginal value of the additional solar power generation facilities is lower than the marginal cost, it is difficult to justify the additional solar investment. In order to be able to obtain the benefits of solar power generation in the short and long term, solutions must be found to prevent the increase in solar power penetration resulting in a decline in value. In fact, the deployment of solar power facilities in the United States fell for the first time in 2017, in part because of the decline in the value of additional solar power. However, things are developing faster than people think.

In 2013, The California Independent System Operator (CAISO) attempted to predict how the influx of renewable energy (especially solar) would affect grid operations. Their predictions are summarized in a well-known payload curve- “Duck Curve” (or Duck Chart).

The chart shows that when solar power resources are added to the grid, there is a risk of generating too much power during the daytime, while at other times there is not enough capacity to meet the user's power needs. The California Independent System Operator (CAISO) estimated in 2013 that by 2020, the grid would need to generate 13,000 megawatts of power generation within three hours.

In the years that followed, California's grid operation showed that the duck curve appeared earlier than predicted in 2013. The grid situation on February 18, 2018, is an example of the increasing trend of the duck curve and the reduction of power supply problems faced by the grid.

Because the form of power generation is not flexible and cannot be rapidly increased or decreased, California Independent System Operators (CAISO) has had to cut back on renewable energy applications while still meeting the power needs of users at night through the power of traditional power plants. In order to meet the power demand during the evening and peak periods, a total of about 13 GWh of renewable energy was reduced in 10 days, which resulted in a net load of 7.5 GW. If the duck curve is not slowed down, any additional solar energy generated during these times will be a reduction, but will not help reduce carbon emissions.

So what can we do?

As solar power generation becomes more and more important, grid operators require solar power generation facilities to provide stable and flexible power, even in the absence of sunlight, as well as key grid services such as frequency regulation and standby diesel engines to stabilize the grid.

One solution to ensure long-term growth in solar power generation is to build solar power generation facilities and energy storage systems that can absorb both excessive daytime power generation and discharge in the evening when carbon-free energy is needed. This allows grid operators to make full use of clean, carbon-free resources to provide customers with enough power during peak demand periods rather than relying on traditional power plants.

California's latest power generation data shows that The California Independent System Operator (CAISO) is facing a serious duck curve and believes that “solar + energy storage” is an effective way to help grid operators around the world and ensure the continued development of solar power.