The New Age Dawns for Solar Energy
The apparently magical ability to create energy from sunlight may seem to be of our age, but has been with us for millennia. Ancient Egyptians used the power of the sun to heat air filled vases embedded in the walls of buildings, giving them the ability to stay cool during the hot days, and warm during the bitterly cold desert nights.
However it was not until 1838 that we first started to harness sunlight to create electricity. The 19-year-old French scientist Edmund Bacquerel discovered the photovoltaic effect whilst doing research in his father’s lab using an electrolytic cell made up of two metal electrodes placed in an electrolyte. It was not until 1879 that the first solid-state photovoltaic cell was made by Charles Frittas, who used gold-coated selenium to create his 1% efficient solar cell.
In 1905, Albert Einstein wrote a paper on the photovoltaic effect, which is said to have inspired William J. Bailey to invent the Copper Collector in 1908, an element still used today.
By 2022, we are reaching over 20% efficiency levels for solar panels, with the Gujarat Solar Park in India, a collection of separate solar farms, boasting a combined installed capacity of 605 Megawatts.
Solar energy is the most abundant energy source in the world. The light and heat radiation that reaches the surface of the earth in 90 minutes is sufficient to supply enough power for the whole planet for an entire year. In addition, solar energy has minimal greenhouse gas emissions, estimates range from 0.07 and 0.18 pounds of carbon dioxide equivalent per kilowatt-hour for a PV cell’s life cycle.
Solar energy is one of the most versatile of today’s energy sources.
According to the MIT Technology Review, researchers at Harvard University have recently made solar cells that are a fraction of the width of a human hair. The cells, each made from a single nanowire just 300 nanometers wide, can be used for powering miniature sensors or in environmental monitoring robots. It has been suggested that these nanowires can be combined to create domestic solar panels at a fraction of the cost of those available today.
In the Majority World, traditional, expensive and often dangerous methods of lighting, such as candles, non-rechargeable batteries and kerosene are being replaced by low-cost solar powered LEDs. The traditional forms have a very low initial cost, but cumulatively can account for 10–25% of a family income. The reducing cost of solar lighting means that families can afford to spend more on food, health and education, breaking the spiral of poverty.
The financing of solar lights is as key to a family in rural Kenya as a multi-million pound array installation in India. The charity Solar Aid have expanded a PAYG scheme, initially tried in Kenya to supply pico-solar, lights the whole of Malawi. The very low 1% default rate proved the successful sustainability of the idea, allowing families to adopt solar energy for the first time.
Solar power plants are also incredibly fast to deploy. After areas of Puerto Rico were devastated by hurricanes, organisations were able to build a number of small yet vital solar energy power stations, with energy storage capabilities in just a few weeks — a timescale unachievable by any fossil fuel source.
The longevity, low noise and ease of maintenance of solar arrays is the envy of the energy industry. A solar power station may last over 40 years, and be easily upgraded as new technological advances emerge.
The growth of the popularity in solar energy is partly due to new innovations and applications for its use. Unlike other renewable energy, it can be deployed for a relatively low initial cost, and is especially suitable for use in small scale and domestic applications.
One of the main constraints of solar energy is the amount of land that is needed. For the whole of the USA to be powered by solar energy, 0.8% of the entire country would need to be dedicated to solar installations. In addition, solar energy does require water for cell cooling, and other hazardous materials that need to be disposed of safely. Researchers are looking into plausible ways to take solar plants to the sea. This gives several advantages over their land based equivalent, including natural cooling, and not requiring to acquire costly land. In 2021, Singapore opened a floating solar farm on the Tengeh reservoir. This 60-MegaWatt-peak solar installation is one of the largest in the world, consisting of 122,000 solar panels.
Architects are using building-integrated photovoltaics (BIPVs) to seamlessly and invisibly integrate photovoltaic cells to the fabric of a building, including walls, roof, doors etc. This has the effect of increasing the energy efficiency of a building, giving better thermal and noise insulation, and ultimately reducing the building’s carbon footprint.
Solar energy is not without adventure. The Bridgestone World Solar Challenge invites teams from around the world to compete in building and running a solar powered car, completing a grueling 2000 mile route through Australia’s outback. This Darwin to Adelaide challenge pushes human and technology to the limit. Harnessing not only the power of the sun, but the passion of the young engineers to create a sustainable future for transport.
Not all solar power ideas proved to be successful however. Smart solar roadways were heralded in 2015 as the future of transportation, utilizing vast areas of land for solar generation, powering road signs, and feeding back energy to the wider community. In practice however they have proved to be impractical; the glass needed to protect the solar cells would not withstand the constant impact of traffic, they are costly, dangerous, and would mean that tarmac, a by-product of the petrochemical industry would have to be disposed of using other means.
Mixed Global Growth
In 2020, solar energy was the second fastest growing renewable energy source, behind onshore wind, and ahead of hydropower. According to the IEA report, the sector produced an additional 134 Gigawatts in just one year. Photovoltaic (PV) energy accounts for 3.1% of all global energy production, and is the third largest renewable energy source. Overall, solar energy has increased from supplying 0.06% of global energy in 2010, to 1.11% in 2019.
The USA experienced a 45% growth in PV generation, fueled partly by the planned phaseout of the production tax credit scheme, along with increased corporate take-up through power purchase schemes. Lower installation costs have created an increase in demand from the corporate and residential sectors.
Although this is good news for the renewable energy sector, there is growing doubt that the average 27% annual capacity growth demonstrated by the sector in the past five years will be sustained to reach the 2030 targets. There was notable expansion in the sector caused by a rush to commission utility-scale projects before the phasing out of the feed-in tariff (FIT) scheme in 2020. These legislative schemes adopted by a number of countries including China, the USA and UK, guaranteed a greater than market value by-back cost for excess solar energy production.
Ironically, power restrictions in certain Chinese provinces in 2021 impacted the production of the raw materials needed for solar panel construction, including metal silicon, polysilicon and solar glass. These raw material supply issues have created a bottleneck, balancing out the global enthusiasm for the take-up of this green energy source.
In December 2021, the UK government announced their largest ever support scheme for renewable energy production. Contracts for Difference (CfD) amounts to £285 million per year subsidies for low carbon technologies, moving the country away from volatile foreign fossil fuel reliance. Although primarily aimed at wind installations, solar energy was specifically included in the funding for the first time since 2015.
The US government favors tax incentives, including the Renewable Electricity Production Tax Credit and the Residential Tax Credit. Their Renewable Energy Certificates allow customers to indirectly contribute to green energy supply, even though their supplier may not use these technologies.
In Europe, the European Commission has agreed a £2 billion scheme to help Greece transit to renewable energy. The scheme encompasses all renewable sources, but as with the UK government, also specifically mentions the use of photovoltaic energy sources.
Impact of Weather and Climate
Solar energy production is dependent on a combination of weather conditions. PV cells only operate during the day as they do require either direct or indirect sunlight. They are also affected by temperature, with cooler conditions generally improving PV cell performance, and wind speed, with higher winds having a beneficial cooling effect on the cells. Higher solar irradiance also increases the ability for PV cells to create energy. Solar irradiance is in turn affected by both cloud cover and the aerosol content of the atmosphere. So warm cloudy days are less efficient than cooler sunny days at creating solar energy.
As with other forms of renewable energy, understanding how the different combinations of weather affect power generation, as well as having foreasts as to when these fluctuations will occur, enables the infrastructure of gas, nuclear, wind and solar to work together at optimal levels.
AI based forecast models are built using detailed historical data, along with historical forecast data to build a model that combines both current weather conditions and forecast data.
The pure versatility and scalability of solar energy generation makes it a key element in achieving the global emission targets. The ability to incorporate PV cells into virtually any application brings the source of the power generation close to the user like no other form or renewable energy.
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