Focus! Solar plane update!

Reducing greenhouse gas emissions is a universal challenge for the commercial aviation industry. This sector accounts for 2.6% of global emissions and this could increase to 5% as the industry lags behind other sectors in the decarbonisation process.

By 2030, more people will be travelling by air, and current airline commitments to use low-carbon alternative fuels will only partially offset this expansion.

Solar energy used by aircraft

Enough sunlight reaches the earth's surface in one hour to meet all of the world's energy needs for an entire year.

Solar systems use photovoltaic modules to convert sunlight into electricity. This energy can be converted into electricity and used in the aircraft industry.

During the fuel crisis of the 1970s, solar energy via photovoltaic modules was seen as an alternative energy source. Solar aircraft have recently gained the attention of the public and the aviation industry as an ecologically beneficial solution. Unlike conventional aircraft, solar aircraft use photovoltaic modules to collect solar irradiation and convert it into electricity.

Solar-powered aircraft are preferred over conventional aircraft

Solar powered aircraft have great potential for high altitude and long endurance (HALE) missions due to the unlimited availability of solar power.

Solar-powered aircraft can fly in the vicinity of space above the atmospheric flight region and below the spacecraft flight region (approx. 20-100 km).

Depending on the durability of the aircraft systems and the availability of sunlight, they can cruise continuously for months or even years, something that is not possible with conventional aircraft due to operational limitations.

How does a solar powered aircraft work?

The basic concept is to cover specific areas of the aircraft, such as the wings and tail, with solar cells.

When exposed to the sun's beam, the photovoltaic modules convert the solar energy into electricity. The orientation of the PV modules and the brightness of the sun are the two elements that affect how much energy is produced.

The circuitry that manages the power transmission output has a programmable microcontroller. The control and transmission system of the electricity ensures that the solar modules produce as much energy as possible. Most of the electricity generated is used to power the aircraft's electronics and propulsion systems. In times of low sunlight, the batteries are recharged using the additional energy.

The basic idea is to use the aircraft to transport solar energy, and the solar modules covering the aircraft perform this task. Using these modules, radiant energy is converted into electrical energy. It is this electrical energy that is used to charge the batteries that power the electric motors.

The propellers mounted on the motors generate constant thrust. The dynamic action of the air thus propels the aircraft and generates a force on the wings that is opposite to the downward force of the weight. The batteries are the only source of energy at night.

Advantages of solar-powered aircraft

Solar-powered aircraft are environmentally friendly. The most important benefit of solar flights and the fundamental reason for their development is that they rely on a clean energy source that has no negative impact on the environment.

Solar energy has significant advantages over fossil fuels because it is a free, clean and renewable source of energy.

Disadvantages of solar-powered aircraft

Conventional flying is less affected by changes in the weather than solar powered aircraft. Conventional aircraft may be delayed by weather, or the journey may become more challenging. However, solar-powered aircraft can only fly in certain weather conditions, especially over long distances, as they need to be recharged in the air.

Although solar energy is practically free, the equipment and technology required to collect and use it is very expensive, especially given the scale required to operate a single-passenger aircraft.

The first solar-powered aircraft and modern aircraft

Electricity has long been used to propel flying machines. The first was a French flying boat filled with hydrogen, which won a 10km race near Villacoulbay and Medon in 1884.

When the petrol engine arrived, electric propulsion for aircraft was abandoned and the field lay dormant for nearly a century. At the time, the electric system had an advantage over its only rival, the steam engine.

In front of an excited audience and photographers, SunPower 2 touched down in Abu Dhabi in the early hours of 26 July 2016. The aircraft accomplished what many thought was an impossible task. After 14 months and 550 hours of flight, it travelled 25,000 miles around the Earth without using any liquid fuel, crossing four continents, two oceans and three seas. The only source of power for this vehicle was the bright rays of the sun.

Recent research and developments in solar-powered aircraft

As with other competing technological approaches, solar fuel cells have been developed to generate electricity for stationary systems. Current research and development efforts are focused on developing reliable, low-cost, high-performance energy networks for aviation applications.

Rapid technological advances are being made to improve and expand the use of solar energy for aviation. In this context, organic photovoltaic systems are of great significance. Organic photovoltaics (OPV) are made from a diverse and versatile range of organic materials and offer unlimited opportunities for a range of performance enhancements. Organic molecules are inexpensive, have good light absorption properties and can enable coatings as thin as a few hundred nanometres.

A recent development in solar powered aircraft is the development of the Zephyr S aircraft. Also known as a drone and pseudo-satellite, the Zephyr S aircraft took off from the US Army's Yuma Proving Ground in Arizona. It is designed to stay in the air for extended periods of time, allowing it to function as a military sensor platform.