Photovoltaics for onboard fish preservation

Researchers at Egypt’s Agricultural Research Center (ARC) have designed a PV-driven thermoelectric cooling prototype for fish preservation during the fishing process.

“Preserving fish caught by fishermen in a cool, low-temperature environment to maintain their quality and keep them in optimal condition, a process known as fish 1st grade, is one of the most important issues facing fishermen,” the research team said, noting that hish preservation on fishing vessels traditionally relies on ice to maintain quality by slowing bacterial growth.

This method, however, is limited by the weight, storage space, cost, and handling requirements of ice. To extend preservation, fishermen often add salt to the ice, although this can alter the fish’s natural taste. Conventional ice cooling also suffers from slow cooling rates, uneven temperature distribution, and short-term effectiveness, while industrial refrigeration systems are costly, energy-intensive, and environmentally unsustainable.

The proposed solar-powered cooling unit (SCU) consists of an insulated plywood cooling chamber equipped with three perforated aluminum shelves to maximize fish storage and airflow.

Four DC fans are installed at the rear of the chamber to ensure uniform circulation of cold air and maintain consistent cooling conditions, while a custom-built fin-and-tube aluminum heat exchanger absorbs heat from the chamber and transfers it through circulating water. Cooling is produced by three TEC1-12706 Peltier modules mounted on a water tank, where the cold side cools the water while the hot side dissipates heat through aluminum heat sinks with forced convection. The chilled water is then continuously pumped through the heat exchanger to remove heat from the storage chamber efficiently.

The SCU is powered by a 300 W photovoltaic panel connected to an maximum power point tracking (MPPT) charge controller and a 12 V, 100 Ah battery, providing reliable off-grid operation for the Peltier modules, fans, and water pump. The solar panel is oriented south at a 31° tilt to maximize solar energy capture during operation.

An automatic control system uses thermostats and temperature sensors to maintain the chamber temperature at 5 °C by regulating water circulation. When the chamber temperature exceeds the set point, the controller activates the pump to circulate chilled water through the heat exchanger, and stops it once the desired temperature is restored.

The energy performance of the solar cooling unit (SCU) was assessed by calculating total energy consumption, specific energy consumption per kilogram of fish, cooling efficiency, and the overall coefficient of performance (COP), which accounted for the Peltier modules, fans, and water pump. The Experimental results were statistically validated using 10,000 Monte Carlo simulations that incorporated both environmental variability and instrument measurement uncertainty to estimate the probability of meeting target cooling conditions.

Assuming a typical artisanal fisherman catches 3 kg of fish per day over 240 fishing days annually, the analysis showed that the SCU could preserve about 720 kg of fish per year. Based on a manufacturing cost of approximately $182 and an annual maintenance cost of $27.3, the system also achieved an estimated payback period of only 0.15 years.

“The findings show that the thermoelectric module has a high potential in improving a direct cooling method,” the scientists concluded. “However, future adoption of this cooling system lies critically on new, better conversion efficiency thermoelectric material discoveries and development of higher efficiency systems.”

The scientists said future research should focus on the comprehensive development and validation of the proposed cooling unit under diverse operating scenarios, including variable thermal loads, different fish species, and seasonal conditions representing both summer and winter operation. In addition, a systematic comparative assessment with existing fish cooling technologies is recommended to benchmark performance, energy efficiency, and economic viability.