Advancements in Solar Photovoltaic Panels

It is widely approximated that 173,000 terawatts (TW) of solar power reaches the earth’s outer atmosphere at every moment ¹. This equates to enough sunlight every hour to power the globe for a year! In theory, only 1.2% of the Sahara Desert, if it were to be covered with solar panels, would be needed to meet the entire world’s energy demands ². The point I am trying to make is just how powerful the sun’s energy is!

Utilisation of solar power dates back to the 7^th century B.C; where, in ancient China and Greece evidence records the use of magnifying glasses or “burning mirrors” to start fires. However, our modern interpretation of using solar power and solar panels, more closely resembles what was a pivotal 19^th Century scientific breakthrough.

French physicist, Alexandre Edmond Becquerel discovered the photovoltaic effect in 1839, (aged only 19). Becquerel observed that certain materials would generate an electric current when exposed to light. Whilst experimenting with wet cells (a single rechargeable unit, containing a liquid electrolyte that conducts charge – hence ‘wet cell’), he noted that the voltage of the cell increased when its silver plates were exposed to sunlight. Becquerel had discovered photovoltaics!

Over one hundred years later, research in 1954 birthed actual photovoltaic (PV) technology. Daryl Chapin, Calvin Fuller and Gerald Pearson developed their silicon PV cell at Bell Labs, New Jersey. Their collective work produced the world’s first solar cell capable of absorbing and converting enough of the sun’s energy to run what are every day electrical equipment. Despite running at a mere 6% efficiency, the silicon solar cell was able to power a toy Ferris wheel and a radio transmitter ³.

Figure 1 Bell Labs engineer testing solar panel in 1954

The physics behind solar panels can seem complex, so stay with me as I break it down. The electrical process within a Photovoltaic (PV) Cell occurs only due to the solar cells composition of two different semiconductors - an element or compound that conducts electricity under specific conditions. A p-type semiconductor element and a n-type semiconductor element joining to create a positive-negative junction.

Figure 2 Photovoltaic Panel

As we appreciate that light behaves both as a wave and a particle ⁴, when solar photons (particles) strike a PV cell, they will either be reflected, pass through or absorbed by the semiconductor material. Once the semiconductor material absorbs enough sunlight, the solar energy excites the electrons in the material. An excited electron is a fascinating event, the electron has gained enough energy to be free from its atomic bond. The free electron carries a negative charge towards the front surface of the PV cell. Consequently, an electrical difference exists; an imbalance of electrical energy from the semiconductor and the surface of the cell. The electron depletion and charge separation creates a voltage – like the positive and negative terminals of a battery, the positive and negative junction of the panel are much the same.

The electrical conductors in the panel (a material that facilitates flow of energy) can absorb the free electrons fleeing the semiconductors. Once the conductors are connected in an electrical circuit to a load (a toy Ferris wheel in the pioneering 1954 experiment), electricity can flow through the circuit.

Now this entire process is just happening in one cell, solar PV panels comprise of many cells and a solar array comprises of lots of panels. An individual PV can only really produce 1 or 2 Watts, just about enough to power a calculator. After PV cells are electrically connected and packaged together you find yourself with a panel!

Solar panels are truly remarkable. They offer the means to generate one’s own electricity without using fossil fuels. Additionally, the cost of panels has decreased by 90% since the 1970s ⁵. Panel efficiency is up from 14% in the 1960s for outer-space applications to 22-23% in modern day commercial panels. Consequentially these two megatrends have significantly reduced return of investment and payback periods.

Figure 3 Declining Solar Panel Prices

Last month the Australian Energy Market Operator instructed one of the country’s biggest batteries to empty its charge and go on standby, domestic roof top solar had pushed grid demand below zero. Albeit Australia receives far more sunlight than we do in Croydon (and their grid infrastructure is much different to ours) this highlights the potential that domestic solar can achieve for grid security. Croydon Community Energy are working towards the ambition of self-generating clean green energy in community spaces. It is thanks to technological advancements in solar panel infrastructure that has facilitated the possibility of community led generation. As we enter 2026, we must continue driving PV technology forward; developing higher-efficiency panels, expanding retrofit accessibility, and fostering robust climate action that lowers energy bills.

Figure 4 Croydon Community Energy Solar Panels at Archbishop Tennison’s School

 References

1. David L. Chandler, Massachusetts Institute of Technology. Vast amounts of solar energy radiate to the Earth. Phys.org. 26 October 2011. https://phys.org/news/2011-10-vast-amounts-solar-energy-earth.html

2. How Many kWh Does A Solar Panel Produce Per Day? The Green Watt. https://thegreenwatt.com/how-many-kwh-does-a-solar-panel-produce-per-day-calculator/.

3. The 70th anniversary of the Bell Telephone Laboratories "Solar Battery" discovery. Science Direct. https://www.sciencedirect.com/science/article/pii/S2772940024000079#fig0001.

4. Wave-Particle Duality. Britannica. https://www.britannica.com/science/wave-particle-duality.

5. The Declining Cost of Solar Panels: Data & Analysis. Greenmatch. https://www.greenmatch.co.uk/blog/decrease-in-solar-costs.