In the race to reach net-zero emissions, countries around the world are looking to scale up and eventually depend on renewable energy to substitute polluting fossil fuels. Solar is the most abundant, fastest, and cheapest energy source on Earth, and it generates minimal greenhouse gas emissions. Although this renewable energy is rapidly growing across the globe, with an increasing number of countries investing in it, there are some factors that could hinder its growth. How does solar energy work and what are the main advantages and disadvantages of this valuable renewable resource?
What is Solar Energy and How Does It Work?
The vital role in which the sun plays in life on Earth has been celebrated since ancient times. Egyptians in Africa were the first people known to use solar energy on a large scale to heat their homes, designating them in a way that could store up the sun’s heat during the day and release it at night. Fast forward to today, societies around the world have developed innovative technologies that allow us to turn the sun’s energy into electricity that powers heating and cooling systems, transportation, lighting, and ventilation, just to name a few.
This energy source is growing fast: between 2010 and 2019, solar rose from 0.06% to 1.11% of the global energy mix. In 2020, it recorded a record growth of 22% as installations experienced a boom. Among the countries that have poured the most money into solar energy are China – by far the largest investor, the United States, Japan, Australia, and India. The latter aims to be a global leader in solar energy, with Prime Minister Narendra Modi committing to increase energy from renewable sources up to 50% by the end of 2030. In Europe, Spain is one of the first countries to deploy large-scale solar photovoltaics and the largest producer of solar-powered electricity on the continent.
Figure 1: Global Solar Energy Generation, 2019
Before we move on to some of the advantages and disadvantages of solar, it is worth answering a question: how does solar energy work?
When sunlight strikes the Earth’s surface, human-made innovative technologies capture their light and heat and convert these into electrical energy. This conversion happens through photovoltaic (PV) panels, which contain cells that can capture the sunlight’s energy. This energy generates electrical charges that move around the cell, causing electricity to flow. An alternative to PV is solar thermal panels: as opposed to PV generating electricity, thermal panels create heat. When installed on a roof facing the sun, they capture the hot sun rays which are used to heat water stored in a cylinder.
While many nations are starting to recognise the vast potential of solar energy – a powerful and extremely beneficial renewable source – there are still some downsides to it. We explore the main advantages and disadvantages of solar energy.
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Advantages of Solar Energy
Solar Is a Renewable Energy Source
As the name suggests, solar power is a resource that never runs out. Unlike fossil fuels, the production of which requires huge efforts, time, and expensive heavy machinery, renewables convert a natural resource – in the case of solar power, sunlight – directly into electricity. Another big factor that makes renewable energy much more attractive than coal, oil, and natural gas is the significant difference in emissions, namely fossi fuels being one of the world’s largest contributors to the generation of greenhouse gases. Renewable energy sources are not only cleaner but also cheaper and easier to produce than any fossil fuel. But what makes solar energy particularly advantageous over other sources of renewable energy?
Solar Energy is Immensely Abundant
In fact, solar is the most abundant energy source on the planet and throughout the years, we managed to develop innovative technologies that could allow us to depend entirely on solar for the rest of our existence. Another huge advantage is that just a tiny fraction of the sunlight we get every day can provide a huge amount of energy. Indeed, the US Department of Energy argues that an hour and a half of sunlight that reaches the planet’s surface generates enough power to meet all of humanity’s energy consumption for an entire year.
Solar Technologies Are Getting More Efficient
Over the years, scientists have made some important advances in the development of solar technologies, notably improving the efficiency of solar panels and battery storage systems as well as their overall durability over time. According to Rhone Resch, President of the Solar Energy Industries Association (SEIA), the global PV sector has been growing at an average of over 40% in the last eight years and major advances in automation, manufacturing, and throughput have considerably improved this technology. Most panels today are between 15% and 20% efficient, meaning that they are able to convert 15% to 20% of the amount of sunlight they absorb into electricity. Panels’ efficiency has improved consistently over the past decade, a promising factor and one that contributes to continued cost reduction. Furthermore, their resistance to extreme weather has been drastically improved, bringing their average durability to about three decades with little to no loss in efficiency.
Improvements have also been made in battery storage systems, which are emerging as a key solution to effectively integrate solar renewables in global power systems on a large scale. Most of the world’s utility-scale storage systems are being deployed in Australia, Germany, Japan, the United Kingdom, and the United States. Small islands and off-grid communities have invested in large-scale battery storage systems to store excess energy. However, an increasing number of small-scale batteries are also being produced and they are expected to complement utility-scale applications by 2030.
Solar Panels Are Getting Cheaper
In the list of the advantages of solar energy, price is an important point. In its World Energy Outlook 2020 report, the International Energy Agency (IEA) confirmed that solar power schemes now offer the cheapest electricity in history. In its 2021 report, the Agency predicted that by 2050, renewable energy generation will keep growing, with solar power production skyrocketing and becoming the world’s primary source of electricity. Solar energy is indeed praised for the relatively marginal operation and maintenance costs of panels. While the cost of panels itself is the most critical part of the overall equation, solar is definitely a cheap source of power that can considerably lower the electricity bill in the long run.
Solar Life Cycle Generates Minimal Greenhouse Gas Emissions
Lastly, solar energy generation’s minimal contribution to global greenhouse gas emissions is one of the main benefits of this renewable energy source. Indeed, solar power produces no emissions during generation itself and studies demonstrate that it has a considerably smaller carbon footprint than fossil fuels over its life cycle. Even though PV modules and other components are made of materials that are mined and processed and thus generate some levels of emissions, solar is still undoubtedly a carbon-smart energy source whose lifetime emissions are insignificant when compared to coal and natural gas. In fact, a coal power plant releases on average 25 times more emissions than the ones produced by a solar power system. Similarly, a natural gas power plant, despite being less polluting than coal, still generates 10 times the amount of emissions generated by a solar array.
Disadvantages of Solar Energy
Solar Energy is Still Expensive for Households
Did we not just say that solar energy is getting cheaper? Well, it is true. However, there are some aspects of solar technology that are still quite expensive. Indeed, purchasing a solar system requires a significant initial investment to cover the costs of panels, inverter, batteries, wiring, and the installation of the system itself. One of the most expensive parts of the system is the batteries used for solar power storage, which can cost upwards of USD$5,000. When solar energy started being commercialised 40 years ago, the price of panels was also incredibly high. Nevertheless, solar technologies are constantly developing and this is contributing to a significant decrease in prices. Statistics show that the average global cost of solar PV modules has gone down drastically in the first two decades of commercial solar power production and it has been slowly but consistently decreasing ever since. Just a decade ago, an average 6-kilowatt hour residential solar system could cost USD$50,000 or more. However, the price has gone down by an annual average of 62% and nowadays, a typical home installation rarely exceeds UDS$20,000.
Solar Energy is Weather Dependent
An undoubted disadvantage of solar energy is that this technology is not equally efficient around the world. While solar power can be generated on a cloudy day, some level of daylight is still required in order to harness the sun’s energy, and the amount of energy that can be produced varies greatly depending on many factors, such as the amount and quality of direct sunlight that the panels receive as well as the size, number, and locations of the panels themselves. Thus, in countries that receive limited sunlight throughout the year, alternative renewable resources like geothermal energy and hydropower might work better. In Iceland, an area with little sunlight and wind, for example, these two energy sources make up 27% and 73% respectively, allowing the country to generate 100% of its energy from renewables.
Solar Power Plants Are Not the Most Environmentally Friendly Option
As we said before, the carbon footprint of solar energy is minimal. However, this renewable still has some aspects, mainly related to land use and waste generation, that can still harm the environment. First and foremost, solar power plants require space. For example, a solar power plant to provide electricity for 1,000 homes would require 32 acres of land. This means that, in order to meet the US energy consumption needs, nearly 19 million acres, equivalent to 0.8% of the entire country, would be necessary.
Another factor to consider is the management and disposal of hazardous materials such as metals and glass needed to build some components of solar infrastructure that are energy-intensive to produce and thus responsible for the generation of carbon emissions. Building PV cells and panels also requires some hazardous chemicals and heavy metals. To avoid harming the environment, such materials necessitate careful management and disposal procedures once the solar plant’s life comes to an end. The International Renewable Energy Agency (IRENA) projects that by 2050, solar energy systems could be responsible for up to 78 million tonnes of waste.
Should We Still Invest in Solar Energy?
The short answer is yes. There is no such thing as a ‘perfect’ energy source. From nuclear and fossil fuels to renewable resources, all of them have many advantages but also some disadvantages. However, as we are quickly running out of time in the race to reach zero emissions, it is crucial that all countries begin to seriously evaluate which sources of energy can bring the most benefits. While solar energy might not be the best solution for northern countries for the lack of sunlight they receive throughout the year, and some of its disadvantages such as the extensive land use that the installation of solar panels requires might not make it the best candidate for everyone, this renewable resource, along with all others, certainly has undeniable potential and it still a better alternative to environmentally unfriendly fossil fuels, beyond being the best chance we have at stopping global warming.