Solar Power: Renewable Energy

We explain the basics of solar energy including the two key types of production plants. Read about the benefits for both climate change and air quality. Switching from dirty fossil fuels to sustainable renewables like solar power, is an essential strategy if we are to limit global warming and clean up the widespread air pollution in cities around the globe.
Solar power park in Pakinstan
Pakistan’s 100 MW Quaid-e-Azam Solar Power Park built in 3 months by a Chinese firm. Photo: QA Solar Power (Pvt) Ltd

Most Promising Alternative to Coal, Oil & Gas

As the threat of climate change intensifies, we must look to renewables like solar power, in an effort to replace traditional fossil fuels with clean energy and thus reduce our emissions of greenhouse gases.

Any effective climate plan or campaign of climate action, must contain the strongest possible commitment to renewable energy. There is simply no alternative.

Of all the renewable energy options, solar is arguably the most promising alternative to coal, oil and natural gas. It has a low impact on the environment and can be harnessed by any country with a sunny climate. Like wind power, solar is an inexhaustible source of sustainable energy and freely available into the bargain.

Here, we discuss the benefits and challenges of solar energy and ask if it can help us reach the target set by the Paris Climate Agreement to achieve net-zero emissions by 2050.

What Is Solar Power?

Solar power/energy is the capture of energy from sunlight which is then converted into electricity.

All of the energy we use on Planet Earth comes from the sun, which is the the fundamental source of energy for our renewable and non-renewable energy system.

Heat from the sun drives water and air currents, which in turn propel turbines to create wind and hydro-power. At the same time, photosynthesis allows plants to grow. Later, these plants die, and are subsumed into the Earth, where over millions of years they become transformed into fossil fuels.

What if we could cut out the middle man, and directly harness all that energy for ourselves? This is the reasoning behind solar power.

The sun is 330,000 larger than earth and at its core it is 27 million degrees Fahrenheit (15 million degrees Celsius). 1 Every second it emits enough power to satisfy global energy consumption for two hours.

Unlike oil and gas reserves which could be gone in the next 50 years, and coal in the next 100 years – the sun’s energy will not run out for another estimated 5 billion years. 2 3

Which makes the sun a perfect source of sustainable energy.

Hot is Good, Right?

Global temperature projections point to an average rise in global temperature of between 0.3°C and 4.8°C (0.5°F to 8.6°F) by 2100, above the pre-industrial baseline 1850-1900.  4

Rising temperatures on Earth may seem like a good thing for solar power. However, recent research by the Massachusetts Institute of Technology (MIT) shows that photovoltaic power output reduces by 0.45 percent for each degree increase in temperature. 5 It turns out that the materials used in solar panels are heat sensitive. Hopefully, developments in materials science will remedy that problem in the near future.

Clean Versus Dirty Energy

Clean energy comes from sustainable sources including: hydropower (hydroelectricity), wind power, solar power, geothermal energy and organic biomass. Next generation renewables include tidal power and wave energy.

Hydrogen power is the latest of the new sustainable energies, although it is still very much in its infancy due to a lack of infrastructure. If all goes well, it could provide an inexhaustible supply of storable energy.

Dirty energy comes from high-carbon fossil fuels, such as coal, its precursor peat, and the more recent hydrocarbons like petroleum (oil) and natural gas. The environmental effects of fossil fuels, in terms of pollution and health can be horrendous.

Types of Solar Power

Currently two types of technologies dominate the solar power industry: Solar Photovoltaic (PV) and Concentrated Solar Power (CSP). 6

These two are similar in that they both use the sun in order to generate power. But otherwise, they are quite different.

PV systems directly convert sunlight to electricity by means of solar panels made of semiconductor materials.

CSP systems on the other hand convert sunlight into heat, which is then used to create steam and generate electricity. More on this below. CSP plants are also known as solar thermal power stations.

Pavagada PV Park, India.
2,050MW Pavagada Solar Photovoltaic Park, India. Credit: Government of Karnataka

Solar Photovoltaics (PV)

A PV solar panel consists of many smaller units called photovoltaic cells. These cells link together to form a solar panel. When sunlight hits these cells, an electric current is created. This current is run through an inverter which converts the energy to usable electricity.

Photovoltaic (PV) system. Diagram of how solar power plant works.
Photovoltaic (PV) systems use semiconductor cells that convert sunlight
directly into electricity. Source: Tennessee Valley Authority (TVA)

(1) Sunlight strikes a solar cell, causing the electrons in the cell to dislodge from their atoms. This creates a current. (2) The current is converted to usable electricity via an inverter. (3) A meter measures the amount of solar power produced. (4) It is then distributed to the public energy grid.

PVs can be used to power small electronics such as calculators, to homes and large businesses.

On an industrial scale, solar PV power plants are commissioned for the purpose of electricity generation.

Top 10 Largest Solar Photovoltaic Power Plants Worldwide

Plant NameLocationCapacity in Gigawatts
Sheikh Mohammed Bin Rashid Al Maktoum Solar ParkUAE230 megawatts currently operational, but scheduled to reach a total capacity of 5 gigawatts.
Golmud Desert Solar ParkChinaThe final capacity is not known but the area should be sufficient for 4 to 5 gigawatts.
Bhadla Industrial Solar ParkIndia2.2 gigawatts
Haixi Delingha Solar ParkChinaSite has enough eventual capacity of at least 2 gigawatts.
Pavagada Solar ParkIndiaPlanned capacity of 2 gigawatts.
Tengger Desert Solar ParkChinaFinal capacity should accommodate up to 1.5 gigawatts.
Anantapur Ultra Mega Solar Park – also known as NP KuntaIndiaScheduled capacity of 1.5 gigawatts.
Benban Solar ParkEgyptScheduled for an eventual capacity of 1.4 gigawatts.
Quaid-e-Azam Solar ParkPakistanPlanned for eventual 1 gigawatt
Jinchuan, GansuChina1 gigawatt. No final capacity has been given.
Source: statista.com 2019

Since multi-megawatt PV power plants require large areas of land, they are usually installed in remote areas, far from cities. 7

In several countries, solar PV already plays a significant role in electricity generation. By the end of 2019, 22 countries had enough PV capacity in operation to meet at least 3 percent of their electricity needs, while 12 countries had enough for at least 5 percent. 8.

Graph showing the countries that produce the largest share of electricity from solar power.
Graph indicates the countries that produce the largest share of their electricity from solar energy. The top 5 were: Honduras (10.7 percent), Italy (8.6 percent), Greece (8.3 percent), Germany (8.2 percent), Chile (8.1 percent). Source: OurWorldinData 2020.

Top 10 Countries: PV Capacity Installation

CountryInstalled Capacity in 2018 (Reported 2019)
China44.3 GW in 2018. This took the total installed capacity in China to 175.4 GW, making it the world leader.
India10.8 GW in 2018.
USA10.7 GW installed, out of which 6.2 GW were utility-scale plants.
European Union8.4 GW – the main drivers being Germany, the Netherlands and France.
Japan 6.7 GW in 2018.
Australia3.8 GW in 2018.
Mexico3.6 GW in 2018. The total installed PV capacity reached 45.9
GW at the end of the year.
GermanyGermany ranked separately, installed 3 GW. The Netherlands, in comparison installed 1.5 GW.
Turkey2.9 GW in 2018.
Source: PVPS Trends in 2019. 9

What’s the Difference Between Solar Parks and Solar Plants?

The term solar plant refers to an individual solar farm project developed by a single developer, which may or may not be spread over different sites or under various stages of development.

Solar parks are multiple plants in one area. Nowadays, the larger solar parks have 50 or more individual solar plants. The concept was was first developed in China and India where suitably vast expanses of land were found that could host several plants.

Concentrated Solar Power (CSP)

Concentrated solar power (CSP) plants use mirrors to focus the sun’s energy on a focal point. Here the heat is collected, and is then used to produce steam which drives a turbine that creates electricity.

CSP. Sunlight tracking mirrors (called heliostats) redirect sunlight towards a receiver at the top of a tower.
(1) Sunlight tracking mirrors (called heliostats) redirect sunlight towards a receiver at the top of the tower. (2) The heat warms water and generates steam. (3) The steam powers a generator which creates electricity. (4) Resultant electricity is transmitted to the power grid. Image: Public Domain

CSP systems can store thermal energy, which means they can be used to generate electricity day and night and on cloudy days. This capability increases the usability of solar thermal technology, as it helps overcome intermittency problems. In comparison, PV systems generate electricity directly, which cannot be stored easily (e.g. in batteries), especially in large quantities.

The biggest problem with CSP power plants is the high cost of construction. A typical CSP requires 5 to 10 acres of land to accommodate the solar panels and thermal energy storage (TES). Plants need access to water resources for cooling, and a high-voltage transmission line to move electricity from the plant to end users.

Top 10 Largest CSP Plants Worldwide

Plant NameLocationCapacity in MW
Noor Ouarzazate Solar Power StationMorocco510 MW. In 2020 a solar energy storage system was introduced, meaning the plant can now produce electricity 24 hours a day. The station comprises 3 CSP plants (Noor I, Noor II and Noor III).
Ivanpah Solar ElectricCalifornia, USA377 MW. Located in the Mojave Desert, across 3,500 acres of federal land, this station can power 100,000 homes.
Solar Energy Generating Systems (SEGS)California, USA280 MW, two-plant facility with an energy storage component in Arizona.
Genesis Solar Energy Project: a California,
USA
250 MW, two-plant facility in Blythe.
Mojave Solar ProjectCalifornia, USA280 MW. Located 100 miles northeast of Los Angeles which can power 90,000 households.
Solaben Solar Power StationSpain200 MW
Solnova Solar Power Station Spain150 MW
Andasol Solar Power StationSpain150 MW
Extresol Solar Power StationSpain150 MW
Ashalim Power Station Israel121 MW. The company states that at full capacity, the plant will help reduce 245,000 tons of CO2 emissions per year, the equivalent of taking 50,000 vehicles off the road.
Source: NoMorePlanet.com 2020

CSP vs PV

Despite CSP being obviously the more efficient system in terms of energy storage – PV is winning the solar race.

In the last few years there has been a shift from CSP power plants to PV. The reason for this, is that PVs generate electricity more cheaply, and as long as this remains the case, it looks like PV will remain the preferred solution.

PV systems have a more proven technology, can be built easier, at lower cost and in shorter time than CSP plants. CSP plants in contrast, need more space, and are associated with more risks for investors.

That said, there is no reason why the two technologies can’t work in tandem in the future. A CSP plant with storage capacity could be used as a complementary solution to overcome intermittency issues for other renewable technologies like PV and wind turbines.

The Benefits of Solar Power

In line with the benefits of renewable energy as a whole, the main attraction of solar energy is the fact it produces very few emissions. Which satisfies the main goal of climate change mitigation.

The list of benefits of solar power is as follows:

1. Affordable Due To Rapid Declining Costs

An important benefit is that solar power is affordable. The average cost of electricity from solar generation continues to fall rapidly.

For example, the cost of electricity from solar PV projects between 2010 and 2018 dropped 77 percent. In the US, non-hydropower renewable energy resources such as solar PV and wind are expected to be the fastest-growing source of electricity generation in the next few years.

2. Reduces Carbon Emissions

Approximately one third of global renewable electricity could be supplied from solar energy by 2050, of which 11.3 percent could be provided by PV and 10.4 percent by CSP. 10 This would contribute 12 percent of the 258 Gt of greenhouse gas emissions that would need to be mitigated globally by 2050.

3. Reduces Air Pollution

The switch from burning fossils fuels to renewables like solar, has a direct impact on urban air pollution – which is a major public health crisis. The toxic haze of the so-called Asian Brown Cloud which hangs over parts of India and China in the winter is one of the reasons why these countries are leading the charge in solar energy.

The health effects of air pollution are well documented, and clean solar power helps to improve air quality by reducing particulate matter (PM 2.5). This in turn drives greater prosperity by reducing ill health and increasing people’s productivity. In fact, for every dollar invested in transforming the global energy system over the period to 2050, there is a payoff of at least USD 3-7 (IRENA, 2019a).

4. Equality and Socio-Economic Benefits

Solar power could become the great equalizer between industrialized and developing nations in the future. Developing countries in Africa and Asia possess a vast amount of untapped renewable solar energy which at present is not being harnessed, but could be in future.

According to the International Solar Energy Society (ISES), 60 percent of the energy growth in the next few decades will take place in the developing world, where about two billion people are currently living without access to electricity. Renewable energy, in particular solar power, could provide a ‘win-win’ solution for all. The developing world could side-step out-dated fossil-fuel technology to feed their growing population, and so spare Planet Earth the burden of emissions. While wealthier nations could use the extra time created to develop the next generation of clean energy technologies.

Current Status of Solar Power

Although solar power has significant advantages over fossil fuels, it only accounts for around 1 percent of the world’s energy consumption, and 2 percent of the share of global electricity (2019). 11

Nonetheless, while current usage remains very low, it still represents a 300-fold increase between 2000 to 2019. 12

Additionally, electricity generated from solar increased by 22 percent in 2019, with China accounting for over half the growth.

As of 2019 the top 10 countries producing the most solar power are: (1) China (2) USA (3) Japan (4) Germany (5) India (6) Italy (7) UK (8) Australia (9) France (10) South Korea.

Chart showing renewable energy generation capacity, 2019.
Net power generating capacity added in 2019 by main technology. Source: Frankfurt School-UNEP Centre/BNEF (2020).

In 2019, more solar power capacity was added globally than all fossil fuel and nuclear energy combined. 13 Twice as much solar capacity was added than wind energy. In fact, new solar capacity was larger than all other renewables put together.

In the United States, solar generation is projected to climb from 11 percent of total U.S. renewable generation in 2017 to 48 percent by 2050, making it the fastest-growing electricity source. 14

Did You Know?

Extreme weather events are the leading cause of failure for PV plants. The effects of climate change on the planet, are impacting commercial life in unexpected ways. Storms, hurricanes and tornadoes – which are occurring in greater frequency thanks to global warming – are the main cause of damage and equipment loss.

The Challenge: Hitting Net Zero

The official position is this: The accelerated deployment of renewables, combined with more electrification (such as electric vehicles) and increased energy efficiency can achieve over 90 percent of the energy related carbon dioxide (CO2) emission reductions needed by 2050. 10

Among all low-carbon technology options, accelerated deployment of solar PV alone can lead to significant emission reductions. By 2050 solar PV could be the second-largest energy source, just behind wind power, and could lead the way for the transformation of the global electricity sector. By then solar PV could be generating a quarter of total electricity needs, globally. 15

The unofficial position is: We are unlikely to reach net zero emissions by 2050 based on renewables alone without compromising the stability of the electricity grid. Sometimes the wind doesn’t blow and the sun doesn’t shine – particularly if you live in certain parts of the world like North America and Europe.

Furthermore, even though geothermal, biomass, tidal and wave power are promising renewable technologies, they are not yet available at scale.

It is possible to develop enhanced battery storage and use smart grid technology to switch between different renewable sources. However, to do so requires billions of investments and a radical redesign of electricity grids across the world, in order to provide the required stability and connectivity.

Few countries are on track to making such an investment. Yet, electricity demand is projected to soar in the coming decades. So we are left with the problem, how can we maintain supply but at the same time decarbonize the system? The only logical answer is nuclear, although the issue is political not logical. Meantime, a new nuclear plant at Sizewell in the UK, is expected to supply 14 percent of the UK’s electricity needs. 16 For more, see our article: Is Nuclear a Replacement For Fossil Fuels?

Future of Renewable Energy

Intermittency and continuity of supply is an issue that continues to undermine the use of renewables in certain sectors. Nuclear fusion is the latest attempt to develop a type of renewable energy that is ‘always-on’. Although theoretically possible, nuclear fusion will take decades to develop.

References

  1. The Sun – NASA []
  2. “How long before fossil fuels run out?” – OurWorldInData []
  3. “Running out? Rethinking resource depletion.” Stuart Kirsch. July 2020 []
  4. Source: Intergovernmental Panel on Climate Change (IPCC) []
  5. “Warmer temps could mean less solar panel efficiency” 2019 Renewable Energy World []
  6. National Renewable Energy Laboratory: “Solar Has The Most Potential Of Any Renewable Energy Source.” thinkprogress.org – 2013 []
  7. “Solar Photovoltaic Power Plants”. April 2017. Rabiul Islam et al. []
  8. IEA PVPS, Snapshot of Global PV Markets 2020 []
  9. IEA Trends in PV applications 2019 []
  10. IRENA, Global Energy Transformation. A Roadmap to 2050. [][]
  11. “Solar in the energy and electricity mix.” Ourworldindata.org []
  12. “The Future of Solar is Bright” – 2019 Harvard []
  13. Global Market Outlook for Solar 2020-2024 – www.solarpowereurope.org/wp-content/uploads/2020/07/31-SPE-GMO-report-hr-hyperlinks.pdf []
  14. Renewable Energy at a Glance – Center for Climate and Energy Solutions []
  15. “Future of Solar Photovoltaic” Deployment, investment, technology, grid integration and socio-economic aspects. Irena.org 2019 []
  16. “New nuclear plant at Sizewell set for green light” BBC 2020[]
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