Last year saw a number of impressive solar power achievements. China began implementing plans for an additional 10 gigawatts of solar capacity annually, while Germany continued to break (often its own) records for solar energy output such as in July when it produced 5.1 terawatt hours in a single month – the equivalent of powering over 500,000 homes for a year.
While mid-twentieth century predictions that solar would account for over 30% of America’s power by the year 2000 have fallen well short, solar does have the potential to be a much more significant form of energy production if we focus on how to harness the sun’s power in the right way and in the right locations. However, to increase the sun’s role in the global energy mix, there are a number of core issues that must be addressed.
Excluding some exceptions such as Germany, where solar has always been high up on the political agenda and therefore backed for rapid development; the most productive places for solar power generation are often in extreme conditions, such as deserts or other arid, salty or corrosive environments.
While deserts might boast the most sunshine, they also pose a number of structural and technical problems. For example, equipment must be capable of withstanding massive temperature variations. Between day and night, the mercury can fluctuate from anything between 60-80 degrees Celsius. Alongside this, some solar plant locations are often located close to coastal areas, meaning that the equipment has to withstand higher levels of salt from the moist air carried in from the ocean. Chile’s Atacama Desert is just one example; winds from the South Pacific, as well as those which travel over the Atacama’s 3,000 sq km of salt flats, carry high levels of salt which can be deposited on the solar farms. Consequently, solar equipment needs to be highly ruggedized to ensure continued performance.
Alongside the extreme environment, solar farms are often remote. Any faults with solar farm equipment can drastically reduce production levels, but fixing problems that arise in these extreme and remote locations is problematic. Support teams are rarely on hand to deliver a quick remedy. Convincing a team of engineers to relocate to the desert is unfeasible, so the key lies in developing technology that notifies you of impending failure before performance is dramatically affected. Technology is emerging that has the potential to support this sort of predictive maintenance in the future.
Another challenge for solar power, along with most other renewables, is its inconsistency. Simply put, the sun does not always shine, which means fluctuating amounts of energy is produced, posing problems for grid managers.
National grid supply needs to be maintained at a standard voltage level. With traditional forms of power such as coal, nuclear and gas, output remains fairly consistent. However, due to the unpredictable nature of solar power generation, sophisticated electronics and digital communications technology are required to ensure the stability of the grid regardless of whether the output of the solar plant is high or low. Perfecting this automation and managing the power electronics needed to regulate grid flow will improve efficiency and ultimately reduce energy wastage.
Perhaps the biggest challenge is how to make best use of supply spikes on a global scale. What is needed is an infrastructure capable of effective transmission of energy to where it is needed from areas where there is a surplus. For instance, if it’s raining in Rio de Janeiro, solar power could be channelled from the Atacama solar fields, allowing grid managers in Brazil to reduce their reliance on fossil fuels to maintain an adequate supply. The key here is in increasing the efficiency of the transmission networks – over many hundreds of thousands of kilometres, the 96% efficiency of traditional High Voltage Alternating Current (HVAC) transmission simply isn’t enough. High voltage Direct Current (HVDC) transmission, cutting heat and transmission waste by 40-60%, has the potential to make the export and long-distance transmission of renewables much more viable.
Short and long-term energy storage can also compensate fluctuations and off-grid operation in areas of weak or non-existent stable grids, i.e. in some areas, solar will supply electricity only when the sun shines and even if there is no connection to any transmission grid.
While there is a lot of work to be done, meeting the challenges of providing large-scale renewable power is a realistic aim and in many cases is already happening. Resolving these technological issues is key to unlocking solar’s larger role in the global energy mix.