Solar energy has a brighter future as perovskite is found (Steve Parsons/PA).
Several countries’ electricity system recorded its “greenest” ever after running without coal-fired electricity during the Covid-19 pandemic. In the USA, renewable energy sources have overcome coal as the energy source (produced 17.5% more electricity) for the first time in over 130 years, with the Covid-19 pandemic driving a decline in coal consumption that has a profound impact for the climate issue. According to the US Energy Information Administration (EIA), renewable energy sources, especially solar power, showed continuous, impressive growth and fast expansion. Solar generated electricity has expanded by 22.5% compared to 2019 (in the same period) and provided almost 2.6% to the nation (Extance, 2019).
In Great Britain, the country’s sunniest spring assisted in generating enough solar power and reduced the carbon emitted to its lowest level ever recorded (Ambrose, 2020). The weather helped wind and solar power providing about 28% of Great Britain’s electricity in May 2019, slightly behind gas-fired power generation, which generated 30% of the energy mix. Also, the low demand for electricity has increasingly suppressed the need for coal as an electricity source.
The similarity between the USA and Great Britain is the significant contribution of solar energy in their energy mix during this pandemic. It indicates that the utilization of solar energy plays a significant role as it offers a more resilient energy source compared to fossil energy because solar energy provides a sustainable supply. Also, the lockdown policy further reduces the need for fossil energy due to slowing business and industry activities. However, the levelized cost of electricity (LCOE) of solar power generation is higher than coal power generation in most developing countries, such as Indonesia, becomes a barrier in solar energy global expansion. Therefore, a technology breakthrough is needed to construct a more efficient and affordable solar photovoltaics, and perovskite becomes an option that needs to be exercised.
Perovskite: an Overview
Perovskite is a material that compounds of a chemical formula ABX3, where ‘A’ and ‘B’ represent cations, and X is an anion that bonds together (Figure 1). Many different elements can be combined to form perovskite structures. Due to this flexibility, perovskite crystals can be modeled to have a wide variety of physical, optical, and electrical characteristics (Clean Energy Institute University of Washington, 2020). Perovskite crystals can be found today in ultrasound machines, memory chips and solar cells.
Figure 1. Schematic illustration of a) 2D and b) 3D perovskite structures (Djurišić et al., 2017).
Since the initial reports on solid-state perovskite solar cells (PSCs) in 2012, there has been a rapid increase in the number of publications in this area, as well as a rapid increase in the reported efficiencies (Djurišić et al., 2017). The latest research about PSCs conducted by NREL records an efficiency of 22%, and it already tops other well-established technologies (Figure 2). The numerous reports of PSCs efficiency are encouraged with an urge to obtain high-efficiency solar cells to support renewable energy growth.
Figure 2. Efficiency chart of different solar technologies (Djurišić et al., 2017).
Despite PSCs’ researches shown a promising result and significant progress, there are several concerns about its further development. Those concerns include the stability, scaling up (large area devices), hysteresis, and possible environmental effects related to the use of lead-based active material (Djurišić et al., 2017). In recent days, silicon solar photovoltaics also become more affordable and comes with a 25 years warranty because of its technological improvement. On the other hand, current PSCs development is only able to come with a 1-2 year(s) warranty (Extance, 2019). Therefore, the development of perovskite is being questioned as it is unlikely to give a significant improvement for solar cell development or replacing silicon solar photovoltaics.
Stability issue becomes one of the biggest challenges as perovskite is a sensitive material. Temperature, illumination, and ambient exposure affect perovskite durability. Although most perovskite firms have conducted and passed a similar durability test with what solar photovoltaics has done, it is still unclear to say that PSCs can perform well in real-life. The reason is that perovskite and silicon have different instabilities. Also, the use of lead-based materials in perovskite causes a major environmental impact. As PSCs are exposed to the air and the temperature is increasing, these can lead to material degradation and threaten the environment in the surrounding area. Consequently, if the bigger size it is made, the higher risk it is produced.
The PSCs’ size also becomes another challenge. The most efficient perovskite record is established on small samples, smaller than 1 cm2, and the performance does not improve in a larger size (Figure 3). A study reported a 6.25 cm2 perovskite cell with 20.6% efficiency. However, it fell to 12.6% when 35 cells were combined into a 412 cm2 module. Microquanta (a perovskite firm from China) holds the record for perovskite ‘mini-modules’ with a 17.3% efficiency with a total size of 17.3 cm2 (Extance, 2019). They are currently aiming to develop a larger module (more than 1,000 cm2 modules).
Figure 3. How solar photovoltaics’ size matters in perovskite development (Extance, 2019)
Apart from the number of issues that perovskite has, it does not halt the effort of its development. Perovskite photovoltaics offer a robust alternative photovoltaic technology with the potential for meager manufacturing costs through solution processing that could compete with silicon. (Mathews et al., 2020) due to PSCs are simpler and cheaper to make than silicon ones are.
The Future of Perovskite
Increasing efficiency is one of the strongest parameters that can increase the economic value of solar technology. As the current technologies hit their limit, the novelties are needed to continue the improvement and reduce the cost of electricity of solar power generation. As a growth strategy, it may be possible to take advantage of the large silicon manufacturing base by manufacturing perovskite-silicon tandems. It presents a distinct opportunity to leverage the sizable market share of silicon, while significantly boosting device efficiency relative to single-junction modules (Mathews et al., 2020). Through perovskite’s technology that is rapidly developed, this material bonding also holds the potential to make tandems economically beneficial. While perovskite-silicon tandems have these advantages, there are challenges to making a cost-effective tandem. Though tandems can achieve higher efficiencies, they are also more expensive and complex to manufacture (Sofia et al., 2020).
The investment decision becomes crucial to decide the path of perovskite-silicon tandem development. A study showed that the LCOE of low-cost perovskite-silicon tandems (blue line) decreased faster than LCOE of high-efficiency perovskite-silicon tandems (orange line) as the perovskite’s efficiency increases (Figure 4). Therefore, investment in tandem technology that utilizes low-cost and lower quality silicon bottom cells provides a much higher opportunity. Perovskite-silicon tandem can be made by using the current and available low-cost multi-crystalline silicon technology (Sofia et al., 2020) and will be boosted by the improvement of perovskite in the future.
Figure 4. LCOE of each single-junction and 4T tandem architecture versus perovskite (Sofia et al., 2020)
As summarized in Figure 5, if these tandems can produce higher capacity, it can significantly decrease the minimum selling price (MSP) of solar photovoltaics. Also, as the manufacturing scale grows, it will drop down the average selling price and have a major impact on achieving sustainable growth of solar photovoltaics. The role of further research and development (R&D) will be essential to generate a new economic value, and developing countries such as Indonesia should grab this opportunity.
Figure 5. How perovskite-silicon tandems impact on solar photovoltaics’ cost and growth (Mathews et al., 2020)
Fishing the Opportunity in Indonesia
Indonesia should consider the development of perovskite-silicon tandem as a way to maximize the potency of solar power. As of 2019, the installed capacity of solar power only reached 97 MW (figure 6), and it is somewhat far to its maximum potency, which reaches 207.9 GW (according to RUEN/national energy plan). This fact indicates that Indonesia has a big prospect to enlarge the solar energy used as it offers more resiliency rather than fossil energy. Therefore, Indonesia should participate in developing perovskite-silicon tandem to maximize this opportunity. Even more, so many countries are still trying to develop it. Indonesia is not necessary to be the leading developer, but it is required to reassure self-reliance on its solar photovoltaics industry. If this is not achieved, Indonesia will be threatened if there are global upheavals such as economic recession and pandemics due to dependence on imported goods.
Figure 6. Installed capacity for Solar PV from 2015-2019 (Purnomo Yusgiantoro Center, 2020)
Indonesia, due to its location (sunshine belt region) and status (developing country), becomes a potential market for solar power expansion. It will surely attract numerous of perovskite firms to collaborate in solar photovoltaics manufacturing. Also, the availability of required raw materials offers adding bargain value. The government should support this condition by issuing supporting policies to guarantee the ease, certainty and sustainability of developing solar photovoltaics. In return, the transfer knowledge must proceed and be the key to realizing the self-reliance on the solar photovoltaics industry.
Even though it is unlikely to meet the energy mix target in 2025, Indonesia should think forward by accelerating the energy transition from fossil energy to renewable energy through multi-nation collaboration. If it is a success, then Indonesia can continue to explore the potency of other new and renewable energy (NRE) sources that are still promising. The main goal is to ensure national energy security, especially when facing global threats.
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Clean Energy Institute University of Washington. (2020). Perovskites for Clean Energy. Retrieved June 23, 2020, from https://www.cei.washington.edu/education/science-of-solar/perovskite-solar-cell/
Djurišić, A. B., Liu, F. Z., Tam, H. W., Wong, M. K., Ng, A., Surya, C., … He, Z. B. (2017). Perovskite solar cells – An overview of critical issues. Progress in Quantum Electronics, 53(June), 1–37. https://doi.org/10.1016/j.pquantelec.2017.05.002
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Mathews, I., Sofia, S., Ma, E., Jean, J., Laine, H. S., Siah, S. C., … Peters, I. M. (2020). Economically Sustainable Growth of Perovskite Photovoltaics Manufacturing. Joule, 4(4), 822–839. https://doi.org/10.1016/j.joule.2020.01.006
Purnomo Yusgiantoro Center. (2020). Installed capacity of renewable energy power. Retrieved June 26, 2020, from https://datacenter-pyc.org/data/statistics/infrastructure/installed-capacity-of-renewable-energy-power/
Sofia, S. E., Wang, H., Bruno, A., Cruz-Campa, J. L., Buonassisi, T., & Peters, I. M. (2020). Roadmap for cost-effective, commercially-viable perovskite silicon tandems for the current and future PV market. Sustainable Energy and Fuels, 4(2), 852–862. https://doi.org/10.1039/c9se00948e
*This opinion piece is the author(s) own and does not necessarily represent opinions of the Purnomo Yusgiantoro Center (PYC)