Solar energy, as a renewable energy source, plays a very important role in reducing greenhouse gas emissions and mitigating climate change. The future lies in an increasingly efficient use of this resource to produce electricity. 

The sun nourishes all life on Earth. This vital resource radiates energy and provides heat and light. Only half of the sun’s radiation reaches the Earth’s surface, the rest is absorbed or reflected by clouds and the atmosphere. Yet we receive enough solar energy to meet, millions of times over, the energy needs of all mankind.

The importance of solar energy

Solar energy is clean, inexhaustible, and vast. Its efficient use can generate electricity, reduce greenhouse gas emissions, and mitigate climate change. The last two represent major global priorities if the survival of humans, wildlife, and ecosystems is to be ensured.

Solar energy can be used directly to generate electricity, to heat and light homes and businesses, and for water heating. There are also many possibilities for commercial and industrial use.

How is electricity produced using solar energy?

It is possible to produce electricity using this energy by using solar panels, which exist in two types:

• Photovoltaic: photovoltaic solar panels directly convert sunlight into electricity through the “photovoltaic effect”. Solar cells are made of semiconductor materials, such as silicon, which generate an electric current when exposed to sunlight. Solar modules consist of several cells connected in series or parallel to generate enough electricity for storage in batteries or to supply directly to the power grid. The maintenance of photovoltaic solar panels is crucial to maintain the efficiency of solar energy conversion.
• Thermal: the temperatures reached when direct solar rays are concentrated can exceed 1000°C. Solar thermal power is known internationally as “Concentrating Solar Power” (CSP). The mirrors used concentrate sunlight, to heat a fluid, generating steam that in turn turns the blades of a turbine, creating a spinning motion of the generator shaft that produces electricity.

What are the advantages of using solar energy to produce electricity?

• It is a free and abundant resource.
• It is not polluting. The only (residual) pollution comes from the manufacture of the equipment needed to build the solar panels.
• Solar plants require little maintenance.
• The technology associated with solar panels is increasingly developed and their cost is increasingly affordable.
• It is a great solution for places with difficult access, since its installation, on a small scale, odes not require large investments in transmission lines.

What about the disadvantages?

• The production of energy is dependent on the weather conditions of the conditions of the country and the region, and is therefore limited during the winter or when there are more adverse weather conditions. 
• During the night, it is not possible to produce electricity, so there is a need for storage of the energy produced when conditions permit.
• The methods of storing solar energy are still considered inefficient when compared to fossil fuels and hydroelectric power (water bodies in reservoirs/dams).

European Union (EU) measures for solar energy

In recent years, the EU has set ambitious targets to accelerate the transition to renewable energy. A growing proportion of Europe’s energy needs are already being met by renewable energy sources, and by 2021, more than 22% of gross final energy consumed in the EU will have been generated using these sources.

But the challenge of the transition to renewable energy sources lies not only in production capacity. Power plants need to be connected to a grid that can accommodate the growing production capacity and bring it to end users.

The “prosumers”

Some regions are increasingly encouraging individuals and businesses to become producer-consumers (prosumers), producing electricity using solar panels to meet their own energy needs and, with the excess, feeding it into the Public Service Electricity Grid (PSUL).

Investment in energy production and storage, besides the obvious benefits of reducing costs, can be crucial to accelerator Europe’s energy transition and reduce greenhouse gas emissions.

Self-consumption of energy in Portugal has already been allowed for many years. Regulation No. 266/2020, of March 20 approved the Electricity Self-Consumption Regulation and the Decree-Law No. 15/2020, of January 14   establishes the operation and organization of the National Electricity System, transposing Directive (EU) 2019/944 and Directive (EU) 2018/2001.

The energy produced is mostly consumed by the producer, but the surplus can be injected into the grid.

Energy crises - such as those that occurred following the war in Ukraine, for example - and their consequences for most countries, and technological developments, which have made photovoltaic solar panels increasingly efficient and affordable, are two factors that have accelerated the adoption of this energy source by more and more people and countries.

The amount of sunlight that hits the Earth’s surface for an hour and a half is enough to supply the entire world’s energy consumption for a year. Eighteen days of sunshine generate the same amount of energy stored in all the coal, oil and natural gas reserves on the planet, according to the U.S. energy efficiency office.

Everything points to solar energy becoming humanity’s main energy source in the increasingly near future.