In this blog post, we will summarize the principles and efficiency of solar power generation, compare it with other power generation methods, and discuss future development directions.

Introduction

We use various forms of electrical energy in all aspects of our daily lives. As conventional energy sources such as coal, oil, and uranium are limited and the issue of depletion becomes a reality, efforts to diversify power generation methods have intensified. One such method is solar power generation.
In South Korea, solar power development has been slower than in other countries due to the country’s geographical characteristics; however, as major steelmakers and other companies have recently entered the solar power business, tangible results are beginning to emerge. This article examines the basic principles and efficiency of solar power generation, compares it with other alternative energy sources, and explores future technological and policy prospects.

Efficiency of Solar Power Generation

Solar power generation is a technology that directly converts sunlight into electrical energy; sunlight triggers the photovoltaic effect in semiconductors and other materials to generate an electric current. A solar power generation system consists of modules made up of solar cells, batteries, and power conversion devices (inverters).
Solar cells are designed to generate electrons and holes when sunlight is absorbed by a structure that combines N-type and P-type semiconductors with different electrical properties, and to allow current to flow when an external load is connected. While there are types such as selenium photovoltaic cells and copper sulfate photovoltaic cells that utilize metal-semiconductor contacts, most commercially available solar cells today use a silicon-based pn junction structure.
Solar cells are broadly categorized into crystalline silicon solar cells and thin-film solar cells. The crystalline silicon series, which is produced by slicing a block of silicon into thin wafers, accounts for a significant portion of the market, while thin-film solar cells are manufactured by depositing a thin film onto a plastic or glass substrate. The type of thin-film varies depending on the materials used for the substrate and the film.
Currently, the conversion efficiency of practical solar cells generally ranges from 5% to 20%. Major energy losses in solar cells include surface reflection losses, non-absorption in the infrared region, energy that is absorbed but cannot be utilized, and losses due to series resistance and leakage. By comparison, while surface reflection and non-absorption losses in crystalline silicon solar cells are approximately 26%, this figure is higher for thin-film solar cells at about 41%. Conversely, the proportion of absorbed but unusable energy is reported to be about 49% in crystalline silicon and about 42% in thin-film cells. Other losses, such as series resistance and leakage, are estimated to be about 7% for crystalline silicon and about 6% for thin-film.
Under standard conditions (ambient temperature 25°C, irradiance 1000 W/m²), the power output per unit area of a solar cell is approximately 100 W. However, system efficiency decreases if partial shading occurs or the surface temperature of the solar cells rises. Typical cell efficiency ranges are 7–8% for thin-film, 11–13% for polycrystalline silicon, 14–15% for monocrystalline silicon, and 17–19% for hybrid cells.
The advantages of solar power generation include the fact that the energy source is clean and virtually unlimited. It can be installed in the required locations in the required quantities, maintenance is relatively easy, and unmanned operation is possible. It also has a long lifespan, offering long-term benefits. On the other hand, disadvantages include the fact that power generation depends heavily on regional solar radiation levels, and the low energy density requires a large installation area. Installation locations are limited by solar radiation levels, and the high initial investment costs and generation costs are also significant drawbacks that cannot be ignored.
When compared to other alternative energy sources, each method has its own characteristics. Geothermal energy utilizes heat from the Earth’s interior, so there is little risk of depletion, and it offers the advantage of enabling ancillary businesses such as hot springs and tourism. However, it is difficult to apply in regions without geothermal resources, and technological development is needed to utilize deep underground sources.
Bioenergy has abundant resources and environmental benefits such as greenhouse gas reduction, and it can be used to produce various products like fuels and chemicals; however, its major drawbacks include the costs of collecting and processing resources, the risk of environmental damage, and high facility investment costs.
Ocean energy (tidal, wave, and ocean thermal) offers vast energy resources, but site selection is challenging, installation costs are very high, and tidal power generation can cause environmental problems such as damage to tidal flats.
Wind power is highly economical in regions with suitable wind conditions, has relatively low installation costs, and requires minimal maintenance. However, in areas where wind direction and speed are inconsistent, power generation is unstable, so multiple facilities must be installed to achieve effective results.

The Current Status and Future of Solar Power Generation

Technological development and adoption ultimately depend on financial support and industrialization capabilities. In the past, both the government and the private sector have invested in the solar power sector, and efforts to secure core technologies have continued through various projects. For example, from 1988 to 2010, numerous projects were carried out in the solar power sector, resulting in investments totaling several billion won.
Crystalline silicon solar cells have already reached the commercialization stage through systemization research, while polycrystalline silicon thin-film cells have secured the basic technology but face slow commercialization due to the burden of investing in large-area, low-cost manufacturing facilities. Compound-based (e.g., CdTe, CuInSe2, etc.) thin-film solar cells offer the advantage of high efficiency, but securing technologies for cost reduction and large-scale production remains a challenge.
Domestic companies and research institutions are also developing solar-related technologies and products. Some companies are producing solar cells and modules, and commercial product development is underway in the inverter and storage battery sectors as well. Research institutions are continuing their research to standardize solar power generation systems and secure core technologies. These industrial and research advancements will serve as a driving force to accelerate commercialization in the future.
To overcome efficiency limitations, it is necessary to consider integration with other technologies rather than relying solely on solar photovoltaics. Solar photovoltaics (PV) and solar thermal energy can be applied complementarily by utilizing the different properties of sunlight. Solar thermal systems consist of heat collection, storage, and utilization, and are used for building heating, cooling, and hot water supply. Depending on the type of collector, there are various methods such as flat-plate, parabolic, and concentrated systems. Currently, integration is not easy due to differences in equipment and operational methods between the two fields, but there is potential for closer integration in the future through technological solutions such as semiconductors.
Another complementary technology is nuclear fusion (tokamak) research. If nuclear fusion is commercialized, it could address the intermittency issues caused by seasonal and regional variations in solar radiation, and it could play a role in overcoming the limitations of renewable energy by providing a stable power supply to large-scale grids. However, nuclear fusion is still in the research and development stage, and it will take time to achieve commercialization.
Overall, solar power technology is trending toward improved efficiency and lower costs. It is expected that the competitiveness of the domestic solar power sector will significantly improve if government policy support, industry investment, and research and development are effectively integrated.

Conclusion

While solar power generation has the advantages of relatively simple principles, abundant resources, and environmental friendliness, it currently has limitations in immediately replacing the large-scale power supply provided by traditional thermal and nuclear power plants.
Challenges remain, including improving efficiency, reducing costs, addressing installation space constraints, and managing seasonal and solar irradiance variability.
However, if government and private support policies, technological development, and integration with other renewable energy sources such as solar thermal energy are achieved, solar power is highly likely to establish itself as a key future energy source. In particular, its potential for use as a distributed power source, such as on residential rooftops, is high, and it will contribute to the diversification of the future energy structure.
While this article has focused on solar power, our energy system can only become more sustainable if various other new and renewable energy technologies also advance. We look forward to seeing these technologies improve and be utilized in ways that enhance the quality of life.