There have been solar cells based on semiconductor technology since the middle of the 20th century, and photovoltaics (PV) have undergone continuous development since that time. Trends have always played a decisive role in the development of PV. An important trend is characterised by technology, market, materials and investors coming together at an opportune moment. Megatrends are indicative of especially strong changes that have a major impact on the development of technology and the market.
Developments in photovoltaics
Bell Labs made the first n-type silicon solar cell to generate electrical energy directly from sunlight as long ago as 1954. At that time, the semiconductor industry was in the very early stages of its development and material prices were still very high. After 1970, the semiconductor industry evolved rapidly, as a result of which suitable semiconductors became available.
The first commercial solar cells were produced mainly using scrap wafers originating from the manufacture of integrated circuits. At the same time, research efforts were initiated with the goal of improving solar cell efficiency. The solar cell structures in use today were devised and first developed in the laboratory in a relatively short period of time. In some cases, however, it would take more than 30 years before industrialised mass production based on these technologies would be made possible.
The majority of todays’ cell concepts were actually invented long before industrial mass production began (see table 1).
Most solar cell concepts were already being demonstrated in laboratories around the world between 1975 and 1995, but they only became relevant for mass production much later. The efficiencies of the best cells as indicated below are consistently improving. Thin film cells have a relatively lower average efficiency in mass production in the module than wafer-based cells, compared to best cell laboratory results.
Principle of industrialised mass production
As a basic principle, mass production can only begin once certain basic conditions are satisfied:
