Solar drying of biomass has gained prominence as a pretreatment step for biofuel production. The literature presents a wide diversity of definitions and terminologies for evaluating solar dryer performance, particularly in systems with supplementary energy inputs, limiting consistent comparisons between studies. This review provides a critical analysis of the main energy-based performance indicators, with emphasis on hybrid systems. Collector and drying chamber efficiencies are examined based on thermal and energy concepts, considering different dryer configurations. Standardized formulations are proposed to better represent the underlying processes and clarify the distinctions between PV and PVT-assisted systems. The analysis shows that collector performance in active systems is more consistently represented when based on absorbed solar energy and electrical power consumed by the fan. Accurate assessment of drying performance requires accounting for the heat of moisture desorption, sensible heating of the product, useful solar energy for air heating, fan power and supplementary energy inputs. Instantaneous efficiencies are more informative than cumulative ones, as they enable identification of less efficient drying periods and provide insights for optimizing operating conditions and reducing energy consumption. Continuous monitoring of key process variables including solar radiation intensity, air and product temperatures, and product mass is therefore required. Overall, this review establishes a consistent framework for the assessment of solar dryers, enhancing comparability and supporting more reliable analyses across studies. Future research should focus on the effects of intermittent and variable airflow rates on system performance.

• View PDF

This study examines the relationship between renewable energy consumption and economic growth in India over the period 2004–2024 using the Autoregressive Distributed Lag (ARDL) model, incorporating key macroeconomic variables including government expenditure, foreign direct investment, population growth, and inflation. The results reveal a stable long-run equilibrium relationship among the variables, indicating that renewable energy consumption has a negative and statistically significant impact on economic growth in the long run, which may be attributed to adjustment costs associated with the transition toward cleaner energy systems, while government expenditure also shows a negative effect and population growth contributes positively to economic performance; in contrast, foreign direct investment and inflation do not exhibit significant long-run effects. Overall, the findings suggest that the relationship between renewable energy and economic growth in India is complex and shaped by structural and policy-related factors, and from an environmental perspective, the expansion of renewable energy can contribute to reducing carbon dioxide (CO₂) emissions and supporting long-term sustainability despite potential short-term economic trade-offs. In addition, the short-run dynamics indicate temporary adjustments toward equilibrium following shocks in the system, reinforcing the importance of gradual policy implementation and supportive institutional frameworks to enhance the effectiveness of renewable energy policies in promoting sustainable economic development in India. Overall, the study highlights the dual role of renewable energy as both an economic and environmental driver within the broader context of sustainable growth strategies.

• View PDF