passive cooling

A global research group has designed a novel PV module cooling system based on multiple cooling sources. The proposed system was able to reduce a PV system temperature by up to 16.7 C and increase power output by over 9%.

The novel technique consists of attaching cotton wicks immersed in the water (CWIWs) to the backside photovoltaic module. The water is supplied to cotton wicks from top to bottom by gravity which the scientists said helps the effective absorption of cotton and reduces water consumption.

Researchers in Iran have tested four different two-layer PCMs across several cooling system configurations and have found that the payback time of the proposed cooling tech is still far from reaching commercial viability. The system, however, was able to improve PV power generation by more than 3% and produce hot water with a temperature of up to 48 Celsius degrees from the solar module’s excess heat.

Developed by Malaysian scientists, the proposed multi-level aluminum fin heat sinks (MLFHS) were found able to reduce the module operating temperature by up to 8.45 degrees Celsius and increase power yield by up to 10.75%. The system cost was estimated at $0.60/W.

An Indian-Malaysian research group has investigated the effectiveness of several passive cooling techniques for solar panels, including the placement of plants around the modules or coir pith underneath them, both of which, surprisingly, offered good performance in terms of temperature reduction and power yield.

Academics have utilized three PCMs, known as RT26, RT35, and RT42, and decided to pack them ascendingly depending on their melting points and heat-flow direction. The system is claimed to allow lower melting rates and longer thermal management of the modules.

Indian scientists tested four kinds of phase change materials (PCMs) for solar module cooling in building-integrated photovoltaics. The PCMs were encapsulated with the PV system and the building envelopes and were also found to be beneficial to the thermal comfort inside the buildings.

French scientists have proposed the use of radiative sky cooling as a passive cooling technique to cut PV module temperatures by 10 C. They claim the method could improve performance by more than 5 W/m2.

A British-Egyptian research group has tested the use of hydrogels beads for PV module cooling. The micro-sized particles were saturated with aluminium oxide (Al2O3) water-based nanofluids and placed below the simulated PV panels. The experiment showed, according to the scientists, that the hydrogels beads were able to significantly reduce the temperature by between 17.9 and 16.3 degrees Celsius.

Researchers in the Middle East have proposed a new passive technology to cool off solar modules, based on highly conductive porous materials.