Solar Power Development

Large conventional photovoltaic power plants could, in some applications, be replaced by more compact concentrated photovoltaic systems using high-efficiency solar cells.

Solar energy is one of the fastest-growing renewable energy sources and can be used to produce both heat and electricity. Its development follows two main directions: large-scale solar power plants covering extensive areas and smaller systems integrated into buildings, infrastructure and vehicles. Advances in solar-cell technology, energy storage and system design continue to expand the possibilities for using solar energy.

General Trends

Electric-vehicle charging stations can be supplied with electricity from photovoltaic systems.

Solar power continues to expand rapidly. According to the International Energy Agency’s Renewables 2025 forecast, solar photovoltaics are expected to account for almost 80% of the global increase in renewable electricity capacity between 2025 and 2030. The future contribution of solar energy will depend on further technological development, investment, grid integration and energy storage.

The potential of solar energy is particularly high in regions with abundant sunshine, including the Middle East and North Africa. In addition to photovoltaic power plants, concentrating solar thermal power plants can use thermal energy storage to generate electricity after sunset and better match electricity demand.

Solar thermal collectors can provide hot water and process heat for households and industry, including in locations without access to the electricity grid. Their use can reduce the consumption of conventional fuels and electricity for heating.

Photovoltaic systems can reduce the amount of electricity that buildings draw from the grid. Building-integrated photovoltaics (BIPV) incorporate solar cells directly into roofs, façades and other building elements. Combined with efficient building design, heat pumps and energy storage, these systems can substantially reduce a building’s dependence on external energy supplies. Complete energy independence, however, depends on local conditions, consumption and the capacity of the energy-storage system.

Building-integrated photovoltaics make use of existing building surfaces and can therefore generate electricity without requiring separate land for solar panels. The technology can be applied to individual buildings as well as larger urban developments. Photovoltaic modules can also be integrated into vehicles, providing supplementary electricity for onboard systems or battery charging.

A small solar-powered three-wheeled vehicle with a photovoltaic panel mounted on its roof.

Solar carports and solar trees provide additional surfaces for photovoltaic electricity generation in urban areas. Carports can supply electricity to nearby buildings or electric-vehicle charging stations, while batteries can store surplus energy for later use, including lighting. Some solar-tree designs also incorporate tracking systems that adjust the orientation of their photovoltaic modules.

Concentrated photovoltaic (CPV) systems use lenses or mirrors to focus direct sunlight onto small, high-efficiency solar cells. Specialised multi-junction cells can achieve conversion efficiencies exceeding 40% under concentrated illumination. Although concentration reduces the required area of expensive semiconductor material, CPV systems also need precise optical components, solar tracking and effective cooling. Their overall performance and economic viability therefore depend on the complete system design and local solar conditions.

Large-Scale Projects

The Desertec concept proposed using the abundant solar resources of North Africa and the Middle East to generate electricity for local consumption and export to Europe. The original plans envisaged the construction of solar power plants with a combined capacity of around 100 GW and approximately 20 high-voltage transmission links between North Africa and Europe. By 2050, the project was intended to supply up to 15% of Europe’s electricity demand. Although the initial large-scale implementation plans were not realised as originally envisaged, Desertec illustrated the potential for international cooperation in solar-energy production and long-distance electricity transmission.

Building-integrated photovoltaics incorporate solar cells directly into building elements such as roofs and façades.

Space-based solar power is a proposed technology in which large photovoltaic arrays collect sunlight in orbit and transmit energy wirelessly to receiving stations on Earth. Outside the atmosphere, solar irradiance is approximately 1,361 W/m², and suitably positioned orbital systems could receive sunlight for much longer periods than ground-based installations. Major challenges include the cost of launching and assembling large structures in space, their long-term operation and the efficient and safe transmission of energy to Earth.

One proposed method of transmitting energy from an orbital solar power station is to convert the generated electricity into microwaves and direct them towards a receiving antenna on Earth, where they would be converted back into electricity. Such a system would require highly accurate beam control, efficient conversion equipment and appropriate safety measures. Concepts such as space elevators have also been proposed to reduce the cost of transporting material into orbit, but they remain speculative and are not an established means of constructing space-based solar power stations.

A solar updraft tower uses a large, transparent collector to heat air, which then rises through a tall central chimney and drives turbines to generate electricity. The output depends on the collector area, chimney height and local solar conditions. Large-scale concepts have proposed collectors several kilometres in diameter and chimneys around 1,000 metres high, with projected electrical outputs reaching hundreds of megawatts. Such installations, however, have not been demonstrated at this scale.

An experimental solar updraft tower was built at Manzanares in Spain in the early 1980s. The installation demonstrated the operating principle on a small scale, with a nominal electrical output of approximately 50 kW. Much larger solar updraft towers have subsequently been proposed in several countries, but the technology has not achieved widespread commercial deployment.

Experimental Solar Technologies

New absorber materials are being developed to improve the efficiency of evacuated-tube solar thermal collectors.

Research into metamaterials and nanostructured absorbers aims to improve the collection and conversion of electromagnetic radiation. Some experimental structures can direct incoming radiation towards an absorbing region, increasing absorption within a selected wavelength range. These concepts may contribute to the development of specialised solar absorbers, although their practical application in energy systems requires further research. The properties of such experimental absorbers depend on their structure and the wavelength range for which they are designed.

Optical nanoantennas are designed to interact with electromagnetic radiation at very high frequencies. In principle, they could be combined with nanoscale rectifiers to convert absorbed radiation into direct-current electricity. The development of sufficiently fast and efficient rectifying components remains a major challenge, and such systems are still experimental rather than established alternatives to conventional photovoltaic cells. Roll-to-roll manufacturing could enable certain nanostructured devices to be produced on flexible substrates in continuous processing lines. Such methods may help reduce manufacturing costs if suitable materials and efficient energy-conversion components can be developed.

Solar-powered high-altitude unmanned aircraft are being developed for long-duration flights in the stratosphere. Equipped with photovoltaic panels and batteries, they can carry communication, monitoring or observation equipment and may complement satellite systems in selected applications. Their operating endurance depends on solar conditions, energy storage, payload and atmospheric conditions.