The deployment and manufacturing of solar in India is 50 years old in 2025. This paper reviews the developments since 1975, and proposes that the recent rapid push in solar utilizes experience developed decades earlier. The paper also presents the current status in 2025 of deployment and manufacturing of solar in India.

Solar photovoltaics (PV) is entering a new era of multi-terawatt deployment, with 2 TW already in service and more than 75 TW predicted in many scenarios by 2050. This next era has been enabled by over five decades of cumulative advances in PV module cost reduction, performance and reliability. The current scale of deployment also introduces new needs, opportunities and challenges. In this Perspective we frame a path forwards based on learning, broadly defined as a combination of expansion of knowledge and advances through research and development, experience and collaboration. We discuss historical topics where learning has driven PV deployment until now, and emerging areas that are required to sustain high levels of future deployment. We expect progress to continue in terms of module price, performance and reliability, driven by advances in PV cell and module design, the emergence of tandem devices and increased focus on extending module lifetimes. Large-scale deployment also means large-scale sustainability and responsibility. We therefore posit that additional metrics, such as the impact on global CO2 emissions, resource consumption and design for reuse and recycling, will become increasingly important to the PV industry and provide opportunities for further learning. Solar photovoltaics is entering a multi-terawatt era, driven by decades of cost, performance and reliability gains. In this Perspective Alberi et al. discuss the role of historical and future learning, highlighting the increasing importance of sustainability considerations.

A longitudinal study of over 2300 degradation rate samples combined from All India Surveys of PV Reliability 2014, 2016 and 2018 is presented. The effect of the STC correction procedure on the mean / median of the distribution of the calculated degradation rate is investigated. It is also demonstrated conclusively that the modules in hot climates degrade at a significantly higher median rate as compared to the modules in non-hot climates. The paper also provides insights for interpreting the time evolution of the calculated degradation rate distributions from various field surveys using a modified nameplate based methodology. It is also shown that broadening of the calculated degradation rate distribution in the subsequent surveys / emergence of a new peak in the distribution can be a signature of a new degradation mechanism affecting a subset of modules at a site.

Solar energy has emerged as the lowest-cost source of electricity in many locations. This low cost, coupled with its clean, quiet operation, has led to it being the fastest expanding electricity-generating technology today. This is true for both large grid-connected installations and small stand-alone systems. Photovoltaics (PV) promises to be a major driver for ensuring reliable energy access for nearly a billion underserved people around the globe, as well as providing the path for the energy transition from a fossil fuel past to a green and sustainable future.

During the last two years, several policy initiatives by the Government of India have created significant industry interest to enhance solar manufacturing in India across the value chain of silicon from polysilicon to modules, as well as thin film solar modules. It is expected that India will be manufacturing about 100–110 GW of solar modules per year by 2027. This will not only be consistent with India's stated deployment goal of 500 GW of ‘non-fossil fuel’ electricity capacity by 2030, but will leave enough capacity for global export. This paper describes the present status of solar manufacturing in India.

25% annual PV growth is possible over the next decade.

This paper describes the processes and initial results for developing a Solar Roadmap for the Republic of Togo, West Africa. The activity followed the IEA/ISA procedure described in the “Solar Energy, Mapping the Road Ahead” document. The roadmap development committee included members from Togo, Europe, Asia, and the United States. The activity was initiated in 2020. The Togo Solar Roadmap development was divided into four Phases: Planning and preparation; Visioning; Roadmap Development; and Roadmap implementation and revision. The first 3 phases have been completed and are reported in this paper. The primary focus of the roadmap is on solar electricity and photovoltaics.

India has been one of the major deployers of solar PV during the last decade, having installed about 50 GW during this period. Since 2021, there has, in addition, been a great deal of interest to set up the solar manufacturing chain in the country, from polysilicon and wafers to cells and modules. Driven by a slew of policies and incentives announced by the government, several companies have announced and embarked on solar manufacturing. It is being estimated that by 2025, there will be about 40 GW of module production in India, some of it with full or partial upstream integration. This would make India one of the two or three leading solar manufacturers in the world. This paper describes the incentives provided and the companies' responses to these incentives. It also describes and recommends technology options available for manufacturing in India, and estimates India's cost competitiveness of manufacturing, comparing countries as well as technologies. The paper further outlines the requirements for ancillary manufacturing units and for concerted R&D and training to support and enable a fully integrated modern solar manufacturing ecosystem in India. Although the focus of this paper is on India, the challenges and opportunities would also be relevant to other countries of the International Solar Alliance (ISA).

As solar deployment world-wide prepares to accelerate after the pandemic, many regions and countries will attempt to build up a sustainable solar manufacturing ecosystem. The reasons for this may be manifold – energy security, job creation, investment in new green technologies, and potential reduction in costs. Questions which arise are whether the full value chain of manufacturing should be taken up, and what are the types of technology to be used. This paper addresses these points, and proposes possible policy and technology paths to be followed for India. It also suggests how lessons being learned in India in solar manufacturing could be applied globally.

Understanding the reliability of photovoltaic (PV) modules under field conditions is one of the primary areas to ensure prolonged operation. This article reported a study on assessing PV modules' reliability under different outdoor environments, using procedures available in the literature. We identified dominant failure modes of PV modules under different climatic conditions of India. Risk priority number (RPN) of different failure modes are estimated by analyzing the consequences of defects in performance and safety. Modules deployed under cold and sunny, hot and dry, warm and humid, and composite climates of India have more varieties of failure modes than those in cold and cloudy and moderate climatic conditions. The frequency of occurrences of benign or cosmetic defects of PV modules varies under different climatic zones. The biggest concerns in old PV systems were hot spots, internal circuitry discoloration, backsheet problems, and grounding wires' corrosion. In the hot zones, primary safety issues were frame grounding corrosion, backsheet problems, hot spots, and nonhot zones were backsheet burn marks, backsheet peeling, and grounding wire corrosion. The defects observed in different climatic zones were analyzed in terms of its possible defect generation route also.

This paper presents the study of the effect of mechanical loading cycle parameters on the crack generation and power loss for two different types of interconnect designs. Mechanical loading at a lower pressure has been found to cause cracks in the cell, whereas higher pressure causes cell cracks along with interconnect breakages. It has been found that there is saturation in the power loss and cell cracks after a certain number of cycles. Lower frequency (slow) DML requires more number of DML cycles to create same level of cracks as compared to high frequency (fast) DML. This helps us to identify an accelerated test protocol for dynamic mechanical loading.

The field‐measured current–voltage (I–V) curves of photovoltaic (PV) modules need to be corrected to Standard Test Conditions (STC) in order to estimate the degradation rates. STC correction procedures have various attributes such as accuracy, requirement of minimum number and types of I–V curves, required irradiance range, and the type of correction (specific points or entire I–V curve) that determine their optimality for specific applications. This paper presents the investigation of accuracy and constraints of six different STC correction procedures for high‐throughput field I–V measurements through experimental and simulation studies. Following STC correction procedures are considered in this paper: IEC 60891‐Procedure 1, IEC 60891‐Procedure 2, Modified IEC 60891‐Procedure 1, Standard Irradiance and Desired Temperature (SIDT) procedure, Anderson procedure, and Voltage‐Dependent Temperature Coefficient (VDTC) Procedure. Eight different simulation models for predicting the performance of PV modules at arbitrary irradiance and temperature are compared, and the simulation model that yields lowest root mean square error and the most accurate estimation of power temperature coefficient is identified. The simulated I–V curves using this model and the experimentally measured I–V curves on a flash tester at different temperatures and irradiances are provided as an input to all of the STC correction procedures. The average percentage errors in correction of maximum power (Pmax), open‐circuit voltage (Voc), short‐circuit current (Isc), and fill factor (FF) were determined as a function of irradiance and temperature during measurement. Systematic biases introduced during correction by certain procedures were also identified. Based on the error estimation, constraints of various procedures, and requirements of high‐throughput field I–V measurements, the most optimal STC correction procedure was identified. Moreover, the analysis of the root cause of superior performance of this procedure is also presented.

In this paper, role of cloud movement in generation of spurious data in PV power plant SCADA systems has been described. Significant deviation from linear relationship between SCADA recorded current vs irradiance in a multi-megawatt PV power plant, which has only one weather station recording the irradiance, is seen in many instances. Such deviations were shown to be the attribution of cloud movements causing varying shading on different blocks of modules connected to different string monitoring boxes (SMBs) and the pyranometer. Such issues leading to spurious signals in SCADA records can be minimized by having more number of pyranometers spread across the plant or by detecting and eliminated these spurious signals from analysis by looking at the time-series data.

The analysis of degradation observed in some highly degraded photovoltaic (PV) modules inspected during the 2018 All India Survey of PV Module Reliability is presented. The influence of parameters like age, climatic zone of deployment, type of mounting, and grounding configuration on the performance of these degraded PV modules is presented in this paper with the aim of identifying the root causes. It was found that Potential Induced Degradation (PID), high Light Induced Degradation (LID) and / or Over rating, Bypass Diode failure in short circuit condition, Cell Cracks, and Hotspots were the major degradation modes in these PV modules.

This chapter covers the largest set of projects in SERIIUS that can be viewed overall as having three distinct themes. First is the development of new low-capital thin-film photovoltaic (PV) technologies by high-throughput manufacturing processes with a focus on solution-based roll-to-roll processing. This effort was highly integrated with the development of thin glass substrates and packaging from Corning, and focused on absorbers made from CuInGaSe2, CuZnSnSeS, organic molecules such as fluorinated polymers, perovskite solar cells based on methyl ammonium lead iodide (MAPbI), and silicon. Significant progress, including world-record devices, was achieved in a number of areas, and substantial improvements in lifetime were attained. Second is an assessment of the stability and failure mechanisms of PV in hot/dry and hot/wet climates. This work included assessing PV module stability across the seven climate zones of India and in the United States. The importance of dust and particulates was assessed. New failure mechanisms were identified, in particular to the hot/dry and hot/wet climates, and an international working group was convened. Coupled to developing new PV technology and understanding degradation pathways, an effort was made in multiscale modeling – from atoms to modules – to begin to connect the basic science to the ultimate deployability of the PV devices and modules. Here, the potential importance of bifacial modules was assessed.

Simulation models for I-V characteristics of PV modules under mismatch conditions often assume ideal bypass diode and ignore the reverse leakage current of cells. In this paper, we present a SPICE based model in which customized reverse leakage current and real I-V characteristics of bypass diodes can be specified. This model is used to gain insight into root causes of some of the unusual I-V characteristics seen in field deployed modules. Different mismatch scenarios for a PV module were simulated for both the modules made up of leaky and non-leaky cells, and the resultant I-V curves were compared. The effect of Potential Induced Degradation (PID) on the I-V curves of PV modules was also simulated under the presence of mismatch. Using this model, we accurately reproduced the I-V characteristics of fielded modules degraded due to PID, and Bypass Diode failure in the short circuit condition.

Electroluminescence (EL) imaging is an essential tool that signifies the inactive areas (dark area in the image) in a PV module which are not visible to the naked eye. A total of ~700 EL images of fielded PV modules taken during the All India Survey of Photovoltaic Module Reliability 2018 (AIS-2018) were considered for this study. Out of the 700 modules, a majority of modules were from large sites (system size > 100 kW). In the analysis, apart from cell cracks, 14 types of defects/ patterns were observed, out of which seven types were not observed in the earlier 2016 Survey. Cracks are segregated into 3 categories, out of which approximately 80% of the modules showed mode A (hairline) cracks. The correlation analysis of observed cracks with I-V data analysis of the corresponding modules indicates that an increased number of cracks led to increase in fill factor (FF) degradation. Out of 700 modules, 92 modules were inspected in both surveys conducted in 2016 and 2018. Out of these 92 modules, 7 modules shown increase in interconnect failure, and 3 modules show drastic changes in number of cell cracks.

This paper presents analysis of Infrared (IR) imaging performed on a total of 793 modules inspected during the All India Survey of PV Module Reliability 2018. It 18% of the inspected modules had Module ΔT (difference between maximum and modal temperature) of more than 4°C under MPPT condition which correlated to a significant increase in power degradation. Also, modules with hotspots show higher degradation than modules without hotspots in both Hot and Non-Hot climates. However, effect of hot cell (Module with Module AT > 4 °C) in hot zone was more significant. It was also seen that Module AT is significantly higher for modules above the age of 5 years. Comparison of the drone based IR imaging to ground based handheld IR imaging is also provided.

This paper presents a simulation study to estimate the accuracy of various STC correction procedures as a function of irradiance and temperature in field. The normalized errors in maximum power (P max ) in STC correction for the IEC 60891 Procedure 1, Modified IEC 60891 Procedure 1 and Standard Irradiance and Desired Temperature (SIDT) procedures were compared at various irradiances and temperatures. Also, the most accurate method to predict I-V characteristics of PV modules based on single diode model was identified by comparing eight different methods. The IEC 60891 Procedure 1 was found to have least normalized error, however it is not always suitable in field as it requires I-V data at various temperatures and irradiances. Out of the remaining two procedures Modified IEC 60891 Procedure 1 is having lowest normalized error compared to SIDT in the range of temperature (50 0 C to 75 0 C) and irradiance (700 W/m 2 to 1000 W/m 2 ) which are typically encountered in outdoor measurements. The primary experimental validation of simulation results has performed at National Centre for Photovoltaic Research and Education (NCPRE).