# The Effect of Heat Sink Properties on Solar Cell Cooling Systems
## 2 Literature Review
### Passive Cooling System  
Passive solar panel cooling has the advantage of not requiring additional power. Several researchers have conducted experiments with passive cooling, including the addition of a phase change material (PCM), passive cooling with a floating system on water, and using a heat sink on the panel. A heat sink will help prevent rising temperatures. To decrease the working temperature of the solar cell, copper heat sinks are generally given aluminum fins. The aluminum fins allow air to flow under the solar panels so that the heat generated is released into the environment. Research conducted by [PERSON] (2017) reduced the working temperature by 6.1 \({}^{\circ}\)C and increased electrical efficiency by 1.77% by adding a flat aluminum plate behind the solar panel as a passive cooling device [23]. Research by [PERSON] (2014) showed that the efficiency of solar cells can be increased due to a decrease in working temperature using the addition of cooling fins below the surface of the solar panel. The average efficiency of a solar panel using fins was 1.8% higher than that of a heat sink without fins [16]. The addition of fins on the solar panel increased the output power by about 5 W compared to a solar panel without fins [16].  
Heat sinks are used as a tool in the cooling process of a system passively or without the help of other energy. In general, heat sinks are designed using materials that have the ability to absorb and dissipate heat well. Copper and aluminum are often used in the manufacture of heat sinks because they have good thermal conductivity values and, therefore, good thermal conductivity. Conversely, materials with lower thermal conductivity are more suitable as insulators [24; 25]. Copper has a higher conductivity value than aluminum, thus, copper is better able to transfer heat [9; 10]. This is evidenced by research conducted by [PERSON] (2019) who compared the rate of heat transfer in glass, stainless steel, copper, plastic, and aluminum cups using heated water The natural convection heat transfer rate obtained the highest value, namely, copper glass of 55.15 watts, followed by aluminum, 29.44 watts; stainless steel, 2.28 watts; glass, 0.17 watts; and plastic, 0.016 watts [24].  
The forced convection heat transfer rate is influenced by the magnitude of the thermal conductivity of the material and the forced fluid velocity. The more quickly the fluid is forced, the faster the heat transfer rate, thus, the time needed is shorter [24]. Increasing the number of fins increases the rate of heat dissipation.  
As heat-conducting materials, copper and aluminum can be used in heat sinks. [PERSON] (2014) compared heat sinks made of copper and aluminum on a microprocessor using MATLAB 7.0 software. Nodes were made of the heat sink to find the heat distribution equation using the finite difference method. The heat distribution is unstable at the heat sink using a time interval of 0.8 s with an iteration time step of the time observation of 1s, 2s, 5s, 10s, 25s, and equilibrium at 35 s. The variation in the color of the contour gradually decreases until thermal equilibrium is reached when iteration dt = 0.8 s at 35 s, where copper produces an average temperature of 59.91 \({}^{\circ}\)C and aluminum produces an average temperature of 59.84 \({}^{\circ}\)C. This proves that copper has better heat conductivity than aluminum, so is highly suitable for use as a material for making heat sinks. The use of copper can increase the heat dissipation capability of solar cells.