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Shedding light on perovskite films

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Shedding light on perovskite films

Photovoltaics decisively contributes to sustainable energy supply. The efficiency of solar cells in directly converting light energy into electrical energy depends on the material used. Metal-halide perovskites are considered very promising materials for solar cells of the next generation. With these semiconductors named after their special crystal structure, a considerable increase in efficiency was achieved in the past years.

Meanwhile, perovskite solar cells have reached an efficiency of up to 25.5 percent, which is quite close to that of silicon solar cells that are presently dominating the market. Moreover, the materials needed for perovskite solar cells are rather abundant.

The solar cells can be produced easily and at low cost and they can be used for various applications. The theoretically achievable efficiency of perovskite solar cells is about 30.5 percent.

To approach this value, optoelectronic quality of perovskite semiconductors must be further increased. In principle, materials suited for photovoltaics are expected to not only absorb light, but to also emit it efficiently. This process is known as photoluminescence. The corresponding parameter, photoluminescence quantum efficiency, is perfectly suited to determine the quality of perovskite semiconductors.

Together with scientists from the Center for Advanced Materials (CAM) of Heidelberg University and the Technical University of Dresden, researchers of KIT’s Institute of Microstructure Technology (IMT) and Light Technology Institute (LTI) have now developed a model, by means of which photoluminescence quantum efficiency of perovskite films can be determined reliably and exactly for the first time. Their results are reported in Matter.

Materials Have More Optimization Potentials than Assumed

“With the help of our model, photoluminescence quantum efficiency under solar irradiation can be determined far more precisely,” says Dr. Paul Fassl from IMT. “Photon recycling is of high importance. This is the share of photons emitted by the perovskite, which is re-absorbed and re-emitted in the thin films.”

The researchers applied their model to methylammonium lead triiodide (CH3NH3PbI3), one of the perovskites of highest photoluminescence quantum efficiency. So far, it has been estimated to amount to about 90 percent.

Model calculations, however, revealed that it is about 78 percent. The scientists explain that previous estimations did not adequately consider the effect of light scattering and, hence, underestimated the probability of photons – the quantums of light energy – leaving the film before they are re-absorbed.

“Our results show that the potential for optimization of these materials is far higher than assumed,” says Dr. Ulrich W. Paetzold, Head of the Advanced Optics and Materials for Next Generation Photovoltaics Group of IMT. The team offers an open-source application based on the model, by means of which photoluminescence quantum efficiencies of various perovskite materials can be calculated.

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SCE Provides Quarterly Updates on Interconnection Capacity Analysis Improvements

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SCE Provides Quarterly Updates on Interconnection Capacity Analysis Improvements


SCE Provides Quarterly Updates on Interconnection Capacity Analysis Improvements

by Brad Bartz

Los Angeles CA (SPX) May 30, 2024






Southern California Edison (SCE) has initiated quarterly status updates to address issues related to the use of Integration Capacity Analysis (ICA) in processing Rule 21 interconnection requests. This comes as a response to concerns raised during the March 5, 2024, Interconnection Discussion Forum. The first report, submitted to the CPUC and various service lists, details SCE’s ongoing efforts to improve ICA processes.

In a proactive move, Southern California Edison (SCE) has begun issuing quarterly updates to the California Public Utilities Commission (CPUC) and related stakeholders on the status of their efforts to address challenges associated with Integration Capacity Analysis (ICA) used in Rule 21 interconnection requests. This initiative follows queries raised during the Interconnection Discussion Forum held on March 5, 2024.



The first of these updates, provided voluntarily by SCE, outlines significant steps being taken to refine ICA processes. This report, dated May 24, 2024, was circulated to the Energy Division and the service lists of R.14-08-013, R.17-07-007, R.19-09-009, and R.21-06-017, ensuring transparency and open communication with all concerned parties.



The quarterly report highlights several key areas of focus, including:



Enhanced Data Accuracy: SCE is working to improve the precision of data used in ICA, ensuring that interconnection requests are processed based on the most reliable information available.



Stakeholder Engagement: Regular meetings and discussions with stakeholders are being held to address any concerns and gather feedback on proposed improvements.



Technological Upgrades: Investments in technology to streamline and expedite the ICA process, reducing wait times for interconnection approvals.



Policy Adjustments: Revisions to internal policies and procedures to better align with stakeholder expectations and regulatory requirements.



SCE’s commitment to providing these updates underscores their dedication to resolving ICA-related issues and facilitating a smoother interconnection process for renewable energy projects. Stakeholders are encouraged to reach out with any questions or requests for further information, highlighting the open-door policy SCE has adopted for this initiative.



Factual Background:



Who: Southern California Edison (SCE)

What: Quarterly status updates on ICA improvements for Rule 21 interconnection requests.

When: First report issued on May 24, 2024.



Bradley Bartz, founder of ABC Solar Incorporated, is a dedicated advocate at the CPUC, receiving numerous filings daily from various stakeholders. The “Today at the CPUC” series aims to provide the solar advocacy community with concise and relevant updates on critical CPUC developments.



CONTACT: [email protected]


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Upcoming Workshop to Address Net Billing Tariff and Net Energy Metering

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Upcoming Workshop to Address Net Billing Tariff and Net Energy Metering


Upcoming Workshop to Address Net Billing Tariff and Net Energy Metering

by Brad Bartz

Los Angeles CA (SPX) May 30, 2024








A crucial workshop hosted by San Diego Gas and Electric (SDG&E), Southern California Edison (SCE), and Pacific Gas and Electric (PG and E) will take place on June 5, 2024, from 1:00 PM to 4:00 PM. This workshop aims to gather feedback from stakeholders on Net Energy Metering (NEM) and Net Billing Tariff (NBT) bills. The workshop is part of the ongoing efforts to refine and implement policies following Decision 23-11-068.

On June 5, 2024, from 1:00 PM to 4:00 PM, major California utilities-San Diego Gas and Electric (SDG&E), Southern California Edison (SCE), and Pacific Gas and Electric (PG and E)-will conduct a workshop focused on the Net Billing Tariff (NBT) and Net Energy Metering (NEM) programs. This workshop, mandated by Ordering Paragraph 16 of CPUC Decision 23-11-068, is designed to solicit input from stakeholders and address concerns related to these critical tariffs.



The workshop is a continuation of the CPUC’s efforts to adjust the NEM framework, which has significant implications for solar energy customers and the broader renewable energy landscape in California. The NBT, established as a successor to the NEM 2.0 tariff, introduces new compensation rates based on the Avoided Cost Calculator (ACC), which generally offers lower rates than the previous retail compensation model. This change aims to address perceived cost shifts from NEM customers to non-participating ratepayers but has been met with concerns from the solar industry about its impact on the adoption of rooftop solar (California Public Utilities Commission) (California Public Utilities Commission).



The new tariff structure under Decision 23-11-068 also includes provisions for virtual net energy metering (VNEM) and aggregated NEM customers, encompassing multifamily residences, agricultural customers, and large facilities such as schools. These successor tariffs are part of a broader strategy to recalibrate incentives and improve grid reliability by aligning customer compensation with the grid’s needs (JD Supra).



The upcoming workshop will be a platform for stakeholders to discuss these changes, provide feedback, and collaborate on solutions to ensure the NBT and NEM frameworks effectively support California’s clean energy goals. Specific details on how to join the workshop will be shared closer to the date.



Factual Background:



Who: San Diego Gas and Electric (SDG&E), Southern California Edison (SCE), and Pacific Gas and Electric (PG and E)

What: Workshop to solicit feedback on NEM and NBT bills

When: June 5, 2024, 1:00 PM – 4:00 PM



Bradley Bartz, founder of ABC Solar Incorporated, is a dedicated advocate at the CPUC, receiving numerous filings daily from various stakeholders. The “Today at the CPUC” series aims to provide the solar advocacy community with concise and relevant updates on critical CPUC developments.



Link to the Solar Bible GPT by Bradley Bartz


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Research team achieves significant solar cell efficiency milestone

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Research team achieves significant solar cell efficiency milestone


Research team achieves significant solar cell efficiency milestone

by Simon Mansfield

Sydney, Australia (SPX) May 26, 2024






A research team has created a tandem solar cell using antimony selenide as the bottom cell material and a hybrid perovskite material as the top cell, achieving over 20 percent power conversion efficiency. This advancement highlights antimony selenide’s potential for bottom cell applications.

Photovoltaic technology converts sunlight into electricity, offering a clean energy source. Scientists aim to enhance the efficiency of solar cells, achieving over 20 percent in conventional single-junction cells. Surpassing the Shockley-Queisser limit in these cells would be costly, but tandem solar cells can overcome this limit by stacking materials.



The team focused on antimony selenide for tandem cells, traditionally used in single-junction cells. “Antimony selenide is a suitable bottom cell material for tandem solar cells. However, because of the rarity of reported tandem solar cells using it as a bottom cell, little attention has been paid to its application. We assembled a tandem solar cell with high conversion efficiency using it as the bottom cell to demonstrate the potential of this material,” said Tao Chen, professor of Materials Science and Engineering at the University of Science and Technology of China.



Tandem cells absorb more sunlight than single-junction cells, converting more light into electricity. The team created perovskite/antimony selenide tandem cells with a transparent conducting electrode, optimizing the spectral response and achieving over 17 percent efficiency. By optimizing the antimony selenide bottom cell, they reached 7.58 percent efficiency.



The assembled four-terminal tandem cell achieved 20.58 percent efficiency, higher than independent subcells. The tandem cell is stable and uses nontoxic elements. “This work provides a new tandem device structure and demonstrates that antimony selenide is a promising absorber material for bottom cell applications in tandem solar cells,” said Chen.



The team aims to develop an integrated two-terminal tandem cell and further improve performance. “The high stability of antimony selenide provides great convenience for the preparation of two-terminal tandem solar cell, which means that it may have good results when paired with quite a few different types of top cell materials.”



Research Report:Sb2Se3 as a bottom cell material for efficient perovskite/Sb2Se3 tandem solar cells


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Tsinghua University

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