|Fig. 1: This figure shows the concentrating solar power radiation in the US between 1998 and 2005. (Courtesy of the DOE)|
In recent years, solar energy has become increasingly popular in California. In fact, in 2014, California produced more solar energy than all the other states in the country combined.  In addition, California has recently become the first state to generate at least 5% of its electricity from solar panels.  The solar energy revolution in California has had significant benefits for the state, and many other states are following Californias lead. Even so, California has faced some surprising challenges in controlling its solar energy output.
Solar energy has exploded in California for a few reasons. The most obvious reason why is because of the year-round, sunny weather in California, providing ample solar irradiation throughout the year (Fig. 1). A second reason is due to public support. A survey by the Public Policy Institute of California in 2016 found that the large majority of Californians support increasing tax credits and financial incentives for individuals and businesses who construct rooftop solar panels in California.  Another contributing factor is a Renewable Portfolio Standard that requires a third of Californias electricity to come from renewable energy sources by 2020.  In 2015, Governor Edmund G. Brown Jr. took this a step further by signing a bill that requires all retail sellers and publicly owned utilizes to procure 50% of their electricity from renewable energy sources by 2030!  The price of solar power has also plummeted. The average cost of solar power declined roughly 70% between 2010 and 2016, and solar electricity now costs roughly the same as electricity generated by a natural gas plant. 
For a few hours in March of this year, solar power accounted for nearly half of the net grid power produced for the first time,  and in 2015, roughly 20,000 new solar jobs were added within the state.  Over 5 million homes in California are currently powered by solar energy.  It has been estimated that if California can achieve its goal of consistently producing a third of its total electricity from renewable energy sources, CO2 emissions from electricity would decrease by about a third. 
Despite the many benefits, there have been some problems associated with solar energy in California. Primarily, the dramatic growth has presented issues. California has produced so much solar energy that in March of this year, Arizona was paid to take some of Californias electricity, so powerlines wouldnt overload. Some solar plants have even been ordered to reduce production.  Perhaps because of this, or maybe because the growth is simply unsustainable, there are signs that the solar energy field may be slowing down. This year, in fact, although it is projected that 13 GW of photovoltaic solar power will be added to the grid, this will be a 10% decrease from 2016. This is challenging for solar energy companies; as people come to expect massive solar energy growth year after year, some companies simply cannot keep up with expectations. The stock of MAC Global Solar Energy is down about 25% from last year.  Another concern is that solar energy is unreliable; electricity demand and supply of solar energy fluctuate based on the seasons and changes in everyday weather.  California does not yet have a suitable strategy managing the renewable energy it has produced.
California leads the nation in the field of solar energy, which has provided enormous benefits for the state. As the technology continues to get cheaper and better, more and more states will continue to follow Californias lead. However, there are still many issues to hammer out. Fossil fuels are still needed to provide backup energy during times when solar energy production is down. Eventually, we will be able to store energy in batteries, but improvements still need to be made to improve efficiency and reduce costs. 
© Ben Vierra. The author warrants that the work is the author's own and that Stanford University provided no input other than typesetting and referencing guidelines. The author grants permission to copy, distribute and display this work in unaltered form, with attribution to the author, for noncommercial purposes only. All other rights, including commercial rights, are reserved to the author.
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