Focus on Photovoltaic Solar Energy

The Growth of Photovoltaic Solar Energy Around the World

Is the growth of photovoltaic (PV) solar energy worldwide limitless? The use of silicon-based solar cells has been rising exponentially for 15 years and new technologies are unveiling promising opportunities. Benoît Lombardet, R&D Director of Total’s Gas, Renewables & PowerIn physics, power is the amount of energy supplied by a system per unit time. In simpler terms, power can be viewed as energy output... business segment, analyzes the future of this up-and-coming source of energy.

Photovoltaic solar technology has been making a rapidly growing contribution to the global energy scene for some 15 years now, as measured by installed capacityThe power generation capacity of a particular plant. It is usually expressed in megawatts (or sometimes even gigawatts)... in gigawatts (GW), i.e., billions of watts. Over 100 gigawatts were installed in 2018, pushing the world above the 500‑gigawatt threshold of aggregate installed photovoltaic capacity. The outlook for 2030 varies significantly, from 1,300 gigawatts for the least optimistic to 5,000 gigawatts for the most optimistic, i.e., between 1.3 and 5 terawatts (TW, trillions of watts). The change from gigawatts to terawatts says it all...

Germany got the ball rolling, but development in the sector is now being driven by the two most populous countries in the world: China, followed well behind by India. The United States and Europe come next, both also increasing their contribution at a steady pace. The world’s growing demand for energy, especially electricityForm of energy resulting from the movement of charged particles (electrons) through a conductor..., and awareness of climate change have accelerated the development of renewable energies such as solar and wind, now competitive with traditional sources. Photovoltaic solar capacity is today equally divided between large solar farms and building-integrated systems.

Are There Limits to PV Development?

There are no limits to PV development in terms of materials. The dominant technology currently used (over 95%) is based on siliconSilicon crystals come from silica, the main compound in quartz and sand. Silicon is a semi-conducting material., the second most abundant element on Earth. Metals (copper, aluminum and silver) are also used to extract the electricity from the solar cells and panels. The only element that may restrict the development of the sector is silver, but as technology improves, the quantities needed to produce a solar panelA collection of photovoltaic cells connected by wires and covered by glass or a plastic film that protects the cells in bad weather... are rapidly dropping. Thin-film technologies use much rarer elements such as indium and gallium, so production may be slowed down depending on their availability. However, the growth of thin films is today mainly limited by the attractiveness of the silicon industry, which has created a hugely powerful, standardized ecosystem with extremely competitive production costs thanks to its scale and volumes, forming a high barrier to entry for newcomers.

Significance of Long-Term Costs

Cost is an important question when it comes to developing these industries. It is closely linked to the production ecosystem. Since 1976, each time global production capacity has doubled, production costs have dropped an average of 24%. This trend has even sped up since 2008, with an annual decrease of between 10% and 20%. Stakeholders in the silicon industry have taken advantage of this economic relationship and continue to improve the performance of their products, even if they are getting closer to the theoretical limits.

The development of a new family of highly promising photovoltaic materials, perovskites, may lead to a breakthrough in the next few years. Perovskite-based solutions are easier to manufacture than their silicon equivalents, as well as being inexpensive and highly efficient. In light of this high potential, considerable research has gone into the new technology, resulting in spectacular progress. Purely based on performance in the laboratory, perovskites now achieve similar levels of efficiency to silicon. However, their long-term stability is still too limited and much improvement is needed for them to offer an attractive alternative to silicon technologies that can guarantee performance for 25 years.

Limits to the Silicon Industry

There are obviously limits to the development of the silicon industry.

Firstly, logistics: many new production plants and supply chains need to be set up to be able to produce several hundred gigawatts per year, and the energy used to power them must be low carbon.

The second limit is related to the first: availability of investments. Currently, around €500 million needs to be invested along the entire value chain to increase production capacity by 1 gigawatt per year. It is very difficult for solar panel manufacturers to make money when there is a price war in the industry and costs are falling. Motivating investors when profitability is low is far from easy, even in China...

Lastly, as has often been pointed out, power grids must be adapted so they can absorb the increasing amounts of renewable electricity from sources that are intermittent by nature. Storage capacity needs to be developed and the way we manage the power grid and consumption needs to be completely rethought to be able to exceed penetration of 20%.

To sum up, the growth of photovoltaic technology goes hand in hand with the development of solutions for electricity storage (batteries, hydrogenThe simplest and lightest atom, the most abundant element in the universe. , etc.) and for the smart management of increasingly complex power grids.

Born in 1977 and a graduate of the École Polytechnique, Benoît Lombardet has been R&D Director of Total’s Gas, Renewables & Power business segment since July 2018.