History and the Development of Photovoltaics

The very first discovery of the solar cell marked the beginning of the change in energy production. This change would be iterated over and over to make new progress in the field of solar energy by researchers and is still going on. The history of solar energy is a story of innovation that all started in the early 19th century.

 

Solar Energy in the 1800’s

 

In 1839, French scientist Edmond Becquerel discovered the photovoltaic effect at the young age of 19. He realized when electrons were in an excited state in a conduction band, they could move freely through a material, thus creating a current. But this wasn’t widely recognized until Einstein wrote a paper about the power of solar for which he eventually received the Nobel prize in 1922. The first solar panel was invented by Charles Fritts in 1883 where he coated a thin layer of selenium with an extremely thin layer of gold. The resulting cells had a conversion electrical efficiency of only about 1%. This invention led to the launching of a movement for producing solar energy.

 

Solar Energy in the 1900’s

 

The solar era began in 1950 when Bell Laboratory scientists focused on photovoltaic (PV) developments and began utilizing silicon to produce solar cells. This breakthrough is credited to Daryl Chapin, Calvin Fuller, and Gerald Pearson which produced an efficiency of 4% only. This breakthrough led the US government to pour more money into solar cell technology. In the 1960s and 1970’s the production of solar panels was made possible but the downside was it was too expensive for mainstream consumers but scientists continued to develop solar energy technology to reduce the cost. With the rise of semiconductors in 1941, Russel S Ohl described a process of forming silicon ingots that led to the first P-N junction cell. Ohl cut a section from the ingot including the top, barrier, and bottom portions, and attached electrodes to the top and bottom portions, yielding the first silicon solar cell. The figure below represents the first-ever patented silicon P-N -EMF (PN junction Electromotive force ) cell.

Fig 1: silicon P-N photo-EMF cell
Source: US patent no. 2,402,662

 

The image below is an advertisement photo that appeared in the 1956 issue of Look Magazine, show off the “Bell Solar Battery” to the American public.

Fig 2: Bell Solar Battery advertisement
Source: 1956 issue of Look Magazine

Solar Energy in the 2000’s

 

In the 1950s the world had less than a watt of solar cells powering electrical equipment.  Fast-forward to the 21st century, 50 years of continued discovery and development of silicon and other PV materials and still ongoing, today solar panels provide electricity to millions of houses worldwide, power up buildings, satellites and provide clean energy all around the world.

The global solar energy installed capacity is estimated to be around 728GW and is estimated to grow up to 1,645 GW in 2026.  Solar energy has exhibited the most rapid cost decline among energy technologies.  The price of silicon PV cells in the 1950s was 76 US$/Watt which significantly declined to 0.20 US$/Watt in 2021. From 2000 – 2019 the prices were reduced significantly but the reductions started to level off after that. The figure below shows the trend in the reduction of the cost.

Figure 3: trend in the reduction of the cost.
Source: PVinsights

 

Bigger factories, the use of automation and more efficient production methods have delivered economies of scale, lower labor costs, and less material waste for the solar sector. The average cost of a solar panel dropped by 90% from 2010 to 2020.

 

Major types of Solar panels available today in the market are monocrystalline, polycrystalline, and thin-film panels. Thin films include cells made by different materials, unlike silicon solar cells.  Each has its own advantages and disadvantages.

 

The Future of Solar Energy

 

Solar energy has advanced at a rate that is astonishing even to experts in the field and now promises to have a prominent role in the ongoing energy transition. According to the Solar Energy Industry Data (SEIA) for the last decade, the global PV industry has been growing at an average compound annual rate greater than 35%. It is for sure that PV deployment will continue to grow as the global energy portfolio transitions more towards renewable energy.

The increase in the module power of the panels from 250 W to 500 W in the last decade resulted in the decrease of the relative contribution of the module cost to the total PV system cost. Silicon solar cells still dominate the market and it will take some time for other generation solar cells to gain market dominance.

One of the key challenges is to reduce cost and improve efficiency, this can be addressed by coming up with new market competitive silicon wafer manufacturing methods at a lower cost. Focusing on crystalline Silicon-based PV technology, this standardized industry has a steep learning curve and is well-positioned to meet the challenge of producing many terawatts of power. We are also reaching the theoretical limit of single-junction solar cells.

Ultimately, tandem technologies can be a solution to tackle this problem however significant research is still required to enable this at low costs for the mass market. Given the fact that this technology is more than fifty years old, more research and development are needed to navigate diverse possibilities.




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