The costs of generating electricity from sunlight have significantly decreased this past decade, but more is needed for the large-scale, global application of solar energy. Manufacturing solar panels and systems still requires a lot of energy and materials, their CO2 footprint needs to be reduced, and high-value reuse of materials is still barely occurring. To achieve the climate targets, solar energy not only needs to be renewable, but entirely sustainable.

For people and planet

In the Dutch paper ‘Time for sustainable solar energy’ (Tijd voor duurzame zonne-energie), TNO shows us what is needed long term to substantially increase the generating capacity of solar energy (also referred to as solar PV) in a responsible way, for people and planet. A total of 700 gigawatt-peak (GWp) is currently installed globally. This supplies no more than four percent of the total global demand for electricity.

Sustainable is more than renewable

‘On top of low costs, sustainability is an essential condition to generate solar energy on an extremely large scale. And doing so is vital if we want to achieve the internationally formulated targets to keep climate change under control. Renewable is good, but being renewable doesn’t necessarily make solar energy sustainable for people and planet indefinitely’, explains Professor Wim Sinke, Principal Scientist of TNO Solar Energy.

Guiding contribution

Following the spectacular drop in costs, TNO believes it’s high time to heavily invest in the reduction of the CO2 footprint of solar energy, the reuse of materials and circularity, ecology, biodiversity, and societal embedding. This involves players throughout the entire chain – from resources, manufacturing, installation, use, repair, reuse, retail, to the consumer.

In various national and international projects, TNO is working on technologies and processes to make genuinely sustainable solar energy a reality. This concerns, among other things, developing new materials and production processes, increasing the energy yield of solar panels, and integrating solar cells and foils in construction elements. Together with industry, TNO wants to offer a guiding contribution to sustainable solar energy.

Reduce quantities of materials and energy

In many places across the world, solar energy is cheaper than electricity generated from fossil fuels. The current 700 GWp will shortly grow into one terawatt-peak, the equivalent of three billion solar panels spread over a surface area of five thousand square kilometres. Still, this is only the beginning.

By 2050 and beyond, an installed capacity of between 60 and more than 100 TWp is anticipated. This is really necessary if the process industry, transportation, and heating in the built environment are all to switch from using fossil fuels to running on electricity. Colossal quantities of materials and energy will be required to generate this amount of energy. And this means these has to drop considerably.

Recycling and circularity

A lot can be gained from the reuse of materials from solar panels at the end of their lifecycle. At present, scarce and valuable materials (such as silicon, silver, and copper) are barely being recovered.

TNO is working with partners on solutions that will make their reuse of solar modules both technologically and financially viable. A revised design could, for example, make it possible to recover all materials at the end of their lifecycle, freeing them up for use in other high-end applications. From design and production to disposal – the entire value chain must be set up with circularity in mind.

Perovskite looks promising

Additionally, as member of the partnership Solliance, TNO is cooperating with research institutes and companies to develop an entirely new thin-film technology. The promising material perovskite can be independently used for solar foils or combined with silicon or another thin film in so-called tandems to generate much higher energy yields.

Perovskite doesn’t contain scarce materials and its production requires much less energy than current solutions, meaning foils made using perovskite have a much smaller CO2 footprint. Through fast and relatively cheap processes, the foils can be deposited on or integrated into a range of materials. At large-scale production costs can therefore be very low.

Sustainable applications

The sustainability of solar energy concerns more than solar cells, panels, and foils. It also concerns sustainable applications in which the generation of solar energy goes hand in hand with a other use of surfaces, with respect for people and the environment. We’re all familiar with solar panels on the roofs and facades of buildings, but solar energy can also be combined with nature conservation, agriculture, horticulture, and infrastructure (such as roads and railway lines).

To make all these applications possible, attractive, and affordable, TNO and its partners are working on solutions that will make solar energy available in any size, shape, or colour. These so-called laminates can be integrated almost invisibly or – quite the opposite – decoratively on roofs, façades, windows, roads, crash barriers, and even cars.

Climate-neutral future

‘By continuing to invest in research and development, solar energy can become cheaper and much more efficient and sustainable. A progressive and ambitious approach could enable solar energy to play a key role in our future global sustainable and climate-neutral energy supply’, according to Wim Sinke.

Collaborate on solar energy sustainability?

Contact Ando Kuypers.

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