It is easy to look out the window in November and think that there is no point in solar energy, but even when it is cold and short days, electricity is produced.
Solar energy is electromagnetic radiation that is emitted by the sun and captured to be converted into useful energy. Plants absorb solar energy to convert sunlight into food through photosynthesis, while humans capture sunlight to convert it into useful electricity using processes such as the photovoltaic effect.
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The electricity produced by solar energy can be used in power grids or stored in batteries. Energy from the sun is abundant and free, and the cost of converting solar energy into electricity continues to fall as solar technology becomes more advanced and efficient. Solar energy is the most accessible and abundant source of energy on Earth. It also has the advantage of producing a lower carbon footprint than fossil fuels, reducing its overall environmental impact.
Definition of solar energy
Our Sun is a star made up mostly of hydrogen and helium. It produces energy in its nucleus through a process called nuclear fusion, in which hydrogen fuses to form a lighter atom of helium. The energy lost in this process radiates into space as energy. A small portion of this energy reaches Earth. Every day, the solar energy that reaches the United States alone is enough to meet our energy needs for a year and a half.
Currently, the United States has a solar capacity of about 97.2 gigawatts. Only about 3% of the electricity generated in the United States comes from solar energy. The rest comes overwhelmingly from conventional fossil fuels such as coal and natural gas. The Department of Energy predicts that by 2030, one in seven homes in the U.S. will have solar panels on their roofs thanks to government incentives and cost reductions through more efficient technology.
In Europe, the capacity of solar energy in 2024 overtook electricity produced from fossil fuels and coal. This leads to a reduction in greenhouse gas emissions from electricity production, because renewable energy replaces fossil fuels.
In addition, the European countries save money that would otherwise be used to buy oil and gas. In the last five years alone – since 2019 when the EU agreed on the green growth strategy for a climate-neutral Europe by 2050 – the development of new photovoltaic plants and wind turbines has saved European countries €59 billion on reduced fossil fuel imports.
This is according to a new analysis from the international energy think tank Ember, which has examined the status of the transition of Europe’s electricity supply. In fact, the transition is happening so quickly that in 2024, solar energy surpassed coal power for the first time. Thus, coal power accounts for an increasingly smaller part of the European power supply.
In addition, gas consumption fell for the fifth year in a row. Overall, the share of electricity from fossil sources in Europe is now at its lowest level in over 40 years.
“Fossil fuels are losing their grip on the EU’s energy supply,” says Chris Rosslowe, senior analyst at Ember.
“When the EU’s green growth strategy was adopted in 2019, few people believed that the EU’s energy transition would get to where it is today, where wind and solar power push coal out of the picture and force gas into a structural downturn,” he says.
As a result, CO₂ emissions from electricity production fell by nine per cent in just one year. Emissions are now less than half of the level at which they peaked in 2007.
This does not mean that the electricity has magically turned completely green. Last year, electricity production in the EU emitted almost 600 million tonnes of greenhouse gases. Nevertheless, this is 630 million fewer tonnes than less than 20 years ago.
Solar energy is growing in all countries
There are still coal-fired power plants in 17 European countries – and in 16 of these 17 countries, coal consumption decreased. This is positive for both the climate and public health, as coal is the most climate-damaging energy source and at the same time causes particle pollution that is very harmful to human health. Particle pollution – not only from coal, but also from cars, agriculture, factories and the like – kills 350,000 Europeans every year. Every time we reduce the burning of fossil fuels, it gets better for our lung health.
Fortunately, coal consumption is now declining in most of these countries. At the same time, solar energy production is increasing in all EU countries.
It’s not just the wealthy countries or the continent’s climate pioneers that install solar panels.
In Poland, where more than a third of electricity consumption comes from coal-fired power, the share of solar energy has increased from zero percent five years ago to nine percent today. This represents an increase from nothing to almost a tenth of the power supply. This is significant and rapid growth. In addition, coal consumption in the country is declining. Solar energy is also increasing sharply in Lithuania, Bulgaria, Austria, Cyprus, Spain, Portugal and Greece. However, the first place in terms of solar energy share belongs to … Hungary, where a quarter of its electricity now comes from solar panels.
Electricity generation Solar
technology can take sunlight and transform it into energy using photovoltaic (PV) solar panels or by concentrating solar radiation using special mirrors. Certain particles of light are called photons. These are small packets of electromagnetic radiation that have different amounts of energy depending on how fast they are moving. Photons are released by the sun during the nuclear fusion process when hydrogen is converted into helium. If photons have enough energy, they can be harnessed to generate electricity.
PV panels are made of single PV cells. These cells contain materials called semiconductors, which allow electrons to flow through them. The most common type of semiconductor used in PV cells is crystalline silicon. It’s relatively cheap, plentiful, and lasts a long time. Of all the semiconductor materials, silicon is also one of the most efficient conductors of electricity.
When photons with a lot of energy come into contact with semiconductors, they can knock electrons loose. These electrons produce an electric current that can be used for electricity or stored in a battery.
Most of the energy produced by solar panels is sent into the electrical grid to be distributed to places that need electricity. Even private solar panels on roofs send surplus electricity back to the power grid. Battery storage tends to be costly, and selling surplus electricity back to power companies is the most cost-effective way to produce solar power at the moment.
Solar thermal energy
Solar thermal energy (STE) technology captures solar energy and uses it for heat. There are three different categories of STE collectors: low, medium, and high temperature.
Low-temperature collectors use either air or water to transfer heat energy collected by the sun to the place that needs to be heated. They can come in the form of glazed solar collectors that heat air to be transmitted through a building, metal walls, or roof-mounted water bladders that are heated by sunlight. They are mostly used for small rooms or to heat swimming pools.
Medium temperature collectors work by moving a chemical that does not freeze through a series of pipes that collect sunlight to heat water and air in homes and commercial buildings.
High-temperature collectors use a series of satellite dish mirrors to efficiently convert solar energy into high-temperature heat that can then generate electricity. The mirrors capture the sunlight and focus it to what is called the receiver. This system then heats the contained liquids and circulates them to produce steam. Just like conventional electricity generation, the steam then turns a turbine, which creates power for a generator to produce the desired electricity.
The mirrors that collect the sunlight must be able to follow the sun’s path throughout the day to maximize their effectiveness. These large systems are mostly used by power plants to produce electricity to be sent through the power grid.
Solar energy today
Solar technology has made incredible strides in recent decades, and it is expected to grow even faster in the coming years. In almost every part of the world, solar energy is the cheapest energy to produce. And costs continue to fall as technology improves. Cost forecasts for one kilowatt hour of electricity produced by solar energy are estimated to be half a cent by the year 2050. That compares to the current commercial grid price of about 6 cents per kWh.
In 2016, the United States Department of Energy launched its goals for SunShot 2030, which include reducing the cost of solar energy generation and drastically increasing the amount of solar electricity generation. Expanding access to solar energy and reducing the time it takes to build solar infrastructure are among the ways the Department of Energy plans to achieve these goals.
Pros and cons
Solar energy is becoming increasingly affordable, and may even become cheaper than conventional energy produced from fossil fuels as the technology becomes more efficient. Government incentives for both homeowners and businesses make it an attractive technology to invest in.
While there are many advantages to solar energy, its disadvantages prevent it from being available to everyone. Unfortunately, not all electricity customers are able to install their own photovoltaic system. Some people don’t own the place they live, or their homes don’t get enough sunlight to make solar panels effective. And while the price of solar panels has dropped dramatically over the past ten years, the initial cost of installing rooftop solar panels is still cost-limiting for many.
On a commercial scale, solar power generation continues to be a way for companies to produce electricity without contributing to the increasing levels of greenhouse gases in the atmosphere. Solar panels can be co-located with commercial crops to reduce the amount of arable land they make unusable for agriculture.
Solar electricity production itself does not emit pollution; however, the production of solar panels, unless they run on solar power, still produces emissions. Solar panels are also not recyclable in most parts of the world. At the end of their useful life, most solar panels are discarded in landfills. This process has the potential to release toxic chemicals into the environment.
Some plants in Europe are pioneering the recycling of solar panels and are finding ways to reuse many of the original materials for new solar panels. This also reduces the environmental impact by reducing the number of new semiconductor materials needed to be extracted and processed. As solar energy increases in popularity and affordability, the demand for solar panel recycling is likely to increase.
Frequently Asked Questions
How much does solar energy cost?
In 2020, the International Energy Agency’s World Energy Outlook report called solar energy “the cheapest electricity in history”. The U.S. solar industry achieved its 2020 cost target of $0.06 per kWh three years early, in 2017, and now aims to reduce costs further to $0.03 per kWh by 2030.
How much of the energy used in the US comes from solar?
The Office of Energy Efficiency and Renewable Energy says that about 3% of all electricity used in the United States comes from solar energy “in the form of photovoltaic (PV) and concentrating solar thermal power (CSP)”.
What are the pitfalls of solar energy?
Solar energy is praised as a renewable alternative to fossil fuels, but while energy production itself is carbon neutral, the production of panels is known to be quite polluting. The panels are made with toxic chemicals that pollute water and degrade air quality. Often they are also made from materials that have been extracted in an unsustainable way. And as of today, they are not recycled on a large scale.
How do you know if solar energy is right for you?
Switching from traditional fossil-based energy to solar energy can benefit you (and the planet) if your home gets five to six hours of sun per day. You should consider the climate where you live, local regulations, solar energy prices in your area, the size of your roof, and whether a solar energy system can increase or decrease your home value.
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