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The Efficiency of Solar PV Panels - Then vs Now...

Charles Fritts and The First Photovoltaic Cell

With solar hitting the headlines at the moment, this week we are taking a look into the changes in efficiency of Solar PV panels and how far the industry has come!

The first photovoltaic cell was produced in 1884 by Charles Fritts, in New York. The significant difference in efficiency lead to the development of fossil fuels vs solar PV - Fritts' invention had only 1% efficiency. Fast forwarding to the mid-1900s, a photovoltaic cell was produced with 14% efficiency which looked promising...

Over the past 10-20 years, a dramatic increase in panel efficiency has been seen compared to other technological progressions. Solar PV's evolution since the 1990s can be seen in further detail below:

Solar PV Timeline of efficiency

Is solar commercially attractive to residential and commercial users?

Technologies have evolved over time through research and development, deployment, and a requirement to find a suitable solution. In the UK, the solar industry has developed to a point where there is no requirement for Government subsidies. The primary comparison tends to mainly be based against the energy prices on offer. With high energy prices in the UK , solar PV is an incredibly attractive proposition for both residential and commercial users.

Specifically for larger commercial users in the UK, solar PV is also quick to implement in comparison to other renewable technologies, such as onshore wind, and provides clean power directly to the industry allowing for the ability to meet carbon emission targets.

Solar PV Technologies

Solar PV development is broken down into three main technologies:

  1. Crystalline - ranging between 20-47% efficiency, the structure has enabled the use of silicon (Si) and arsenide (GaAs).

  2. Thin Film - introduced in the 1970s by researchers, with a 20-25% efficiency rate and often used a more cost-effective solution than silicon based panels.

  3. Emerging - new technologies such as Perovskite, have broken through but are currently in the infant stage of development. These are currently ranging between 18-25% efficiency.

The most efficient and widely used materials today are that of Crystalline and Thin Film, currently ranging between c.23-27% efficiency on the market. Researchers are working on producing a +40% efficient panel however, this has not been made publicly and commercially available by the NREL yet, with further developments currently under way.

Swanson's Law

Richard Swanson, the founder of SunPower (an American solar manufacturer) observed that as global manufacturing of solar panels doubled over time, there was a reduction in cost of panels by 20%. Known as Swanson's Law, the methodology shows that during the early 1990's, the cost of silicon solar PV panels remained consistent. However, as Government initiatives developed there was a significant increase in demand of panels, leading to a reduction in cost again.

Graph showcasing Price history of silicon PV Cells

As efficiency increases, there is a strong commercial steer towards an increased demand, therefore resulting in further reductions in cost per watt. Thin Film PV cells are considered the cheapest to manufacture and install. They required less material and are therefore lightweight, generate less waste, and are easier to manufacture. In turn, this lends itself to an easier and lower cost installation process than that of Crystalline panels.

For Clean Energy Capital, as the industry continues to grow, the Levelised Cost of Energy (LCOE) for solar PV will reduce which will in turn will allow us to produce even more commercially attractive propositions for both businesses and landowners. The overall cost reduction of Crystalline panels has been 90% per megawatt hour since 2009, which is a testament to the industry's growth and to Swanson's law. Suppliers have found efficient and innovative ways to drive down the costs of generation, installation and maintenance, as well as usage - making it the ideal accessible and affordable solution.

In summary, solar power offers a lower-cost solution considering the recent increase in power prices. Industry pressure to decarbonise is also leading to a significant drive towards efficient methods of producing power. Solar PV has now hit a milestone in efficiency, making it a very commercially viable player in the industry. However, there is plenty of development still to come and the potential for extremely low-cost power that would be hard to argue against. For solar, the development of +40% efficient panels which will become available in the future, the UK and the rest of the world have an opportunity to reach net zero targets sooner.

Written by Tom Sater - Commercial Manager, Clean Energy Capital

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