Performance Comparison Between Hot Mirror and Cold Mirror as a Beam Splitter on Photovoltaic - Thermoelectric Generator Hybrid Using LabVIEW Simulator Zuryati Djafar * , Andi Zahirah Salsabila, Wahyu H. Piarah Mechanical Engineering Department, Faculty of Engineering, Universitas Hasanuddin, Jl. Malino, Borongloe, Bontomarannu, Kabupaten Gowa, Sulawesi Selatan 92171, Indonesia Corresponding Author Email: zuryatidjafar@unhas.ac.id https://doi.org/10.18280/ijht.390524 ABSTRACT Received: 17 July 2021 Accepted: 22 September 2021 Solar energy can be converted into electrical energy using photovoltaic (PV) and thermoelectric generators (TEG). In order to increase the effectiveness of energy absorption, a hot mirror or cold mirror spectrum separator is used. In this study, a simulation was carried out to see the effect of the cold mirror and hot mirror spectrum separator on the performance of the PV-TEG hybrid. Simulations are carried out using the LabVIEW program. The standard for the solar radiation spectrum used is AM1.5D. The incoming radiation is transmitted using a Fresnel lens to make it more focused and then transmitted to a cold mirror or hot mirror, where the spectral irradiance will be halved. Spectral irradiance with a wavelength of 400-690 nm will be directed to PV and a wavelength of 710-1150 nm will be directed to TEG. From the PV-TEG hybrid modeling and simulation using the LabVIEW program, the resulting power and efficiency are 240.635 W/m 2 and 27% respectively for cold mirror and 228.835 W/m 2 and 25.76% for hot mirror. Keywords: cold mirror, hot mirror, light spectrum, output power, photovoltaic, thermoelectric generator 1. INTRODUCTION Solar energy is the energy that is abundant, continuous, and environmentally friendly because it does not produce harmful carbon emissions like burning fossil fuels. Solar energy is included in the renewable energy group. Regarding on the statement above, numerous researches on the development of renewable energy have been conducted, one of which is the development of the use of solar energy. The history of human civilization records that solar energy has greatly influenced all aspects of human life and the environment since the beginning of life in this world [1]. The rate of energy emitted by the sun arriving in the atmosphere is 1386 W/m 2 , and those arriving on the earth's surface can reach 1000 W/m 2 in clear weather conditions. This is due to the influence of the earth's rotation on its axis, the earth's circulation on its trajectory and the gases in space [2]. The main problem in the utilization of solar energy is the day and night factor which always alternates so that the continuity of solar energy acquisition is always cut off at night. However, besides being able to be used directly during the day with the aid of an energy conversion device, it can also be stored in the battery for use at night [1]. As explained previously, solar energy can be converted into electrical energy using energy converters such as solar cells or photovoltaic (PV) cells. The results of the research according to Makki et al. [3] showed that PV can absorb up to 80% of solar radiation, but not all of it can be converted into electrical energy but become heat waste which can increase cell temperature that can cause a decrease in PV efficiency. Research on PV cooling techniques to maintain temperature stability by utilizing heat waste has been carried out using gas and liquid fluids [4-6] and the use of thermoelectric coolant (TEC) [7]. In addition to the thermoelectric coolant (TEC), there is also a thermoelectric generator (TEG) which is a power generating device the resulted from the temperature difference between the two sides of the TEG. The research advancement by stacking up PV and TEG to increase the output power and increase the efficiency has been conducted by Chang et al. [8]. Research on the combination of photovoltaic and thermoelectric generators known as PV-TEG has been carried out by several researchers [9-15] with various configurations where each PV and TEG receive direct sunlight. Another further development model of the PV-TEG hybrid is to separate the spectrum of infrared (IR) light, ultraviolet (UV) light, and visible (VL) light from the sun [16-21] which is known as a beam splitter. This development was carried out because it wanted to produce maximum performance of PV and TEG. Hariyanto et al. [22] have conducted research on simulating PV-TEG hybrid with beam splitter hot mirrors using the standard AM1.5D solar spectrum and a hot mirror, where wavelengths 400-690 nm are transmitted to PV and 690-1150 nm are reflected to them. TEG. The result is a maximum total power of 0.554 W with an efficiency of 67.25%. Another research on simulated PV-TEG hybrid with beam splitter hot and cold mirrors using low intensity have been conducted by Piarah et al [23] using AM1.5G solar spectrum at variations of 0.05, 0.1, 0.25, 0.50 and 0.7 Sun. The light spectrum is concentrated using a Fresnel lens and then transmitted to a spectrum separator (hot and cold mirrors). The simulation results showed that by using cold mirror, the maximum total power is better than hot mirror. International Journal of Heat and Technology Vol. 39, No. 5, October, 2021, pp. 1609-1617 Journal homepage: http://iieta.org/journals/ijht 1609