Srinivasa K Reddy

Temperature management in photovoltaic (PV) is critical for the power output. Phase Change Material (PCM) usage enables one to remove heat from the system and achieve enhanced electrical output. This study aims at finding the period of PV electrical enhancement, the increase in power and increase in electrical efficiency achieved using PCM under different working circumstances. Results suggest that as the angle of approach of wind changes from 75° to 0° the electrical enhancement period elevates from 7.0 h to 8.6 h for 5 cm deep PCM box. But, the increase in power drops from 17.6 W/m 2 to 13.6 W/m 2 . As wind speed changes from 6 m/s to 0.2 m/s, the electrical enhancement period drops from 9.1 h to 6.4 h. But, the increase in power rises from 11.8 W/m 2 to 22.8 W/m 2 . The rise in ambient temperature 289 K to 299 K leads to decrement of electrical enhancement period from 12.6 h to 7.1 h. But the increase in power rises from 15.9 W/m 2 to 21.4 W/m 2 . Elevation in temperature for liquification from 291 K to 301 K leads to increment of electrical enhancement period from 6.5 h to 12.3 h.

In photovoltaic (PV) cells, a large fraction of solar radiation gets converted into heat which raises its temperature and decreases its efficiency. The heat can be extracted by attaching a box containing phase change material (PCM) behind the PV panel. Due to large latent heat of PCM, it can absorb heat without rise in temperature. It will lower down the PV temperature and will increase its efficiency. The available numerical studies analysed the vertical PV-PCM systems. However, PV panels are generally tilted according to latitude of the place. Thus, in the current work, performance analysis of the tilted PV-PCM is carried out. The effects of tilt-angle, wind-direction, wind-velocity, ambient-temperature and melting-temperature of PCM on the rate of heat extraction by PCM, melting process of PCM and temperature of PV-PCM system are also studied. The results show that as tilt-angle increases from 0° to 90°, the PV temperature (in PV-PCM system) decreases from 43.4 °C to 34.5 °C which leads to increase in PV efficiency from 18.1% to 19%. The comparison of PV-PCM with only-PV is also carried out and it is found that PV temperature can be reduced by 19 °C by using PCM and efficiency can be improved from 17.1% to 19%.

In photovoltaic (PV) cells, a large portion of the solar-irradiance becomes heat which shoots the cell temperature up and decreases its electrical efficiency. The heat can be removed using phase-change-material (PCM) at the rear of the PV. In literature, the researchers have reported the performance of PV-PCM for their respective locations. However, selection criteria for climates suitable for PCM integration are not reported yet. Thus, it has been carried out in the current work. The model has been validated against the experimental measurements. It has been concluded that (i) the climates having less variations in the ambient temperature are more suitable for PCM integration. The electricity enhancement achieved by PV cooling is 9.7%. It reduces to 6.6% for the climate having large variations, (ii) Heat extraction by PCM-systems is more effective in warm climates in comparison to cold climates, (iii) PCM integration performs better in climates with low wind-speed, (iv) PCM is more effective for the climates where wind-flow is across the PV and (v) Climates having high solar-radiation is better for heat removal by PCM.

For low/high concentration, when the distribution of solar radiation is non-uniform over the surface of the solar cell, it gets heated up non-uniformly which affects the cell efficiency. Thus, in the present work, three dimensional analysis of the solar cells is carried out under non-uniform solar flux. It involves partial differential equations. For silicon cells, studies are available that use numerical techniques (involving iterations) to solve the differential equations. However, if the differential equations can be solved analytically, one can get an analytical expression for three dimensional non-uniform temperature distribution of the cell. The current work aims at it. Dye-sensitized (DSSC), perovskite and mono-Si cells are investigated. The effects of wind direction, its speed, inclination and solar irradiance on the three dimensional temperature distribution, heat losses and cell efficiency have been investigated. It is concluded that with increase in wind azimuthal from 0° to 90°, the efficiency decreases from 22.1% to 21.3% for mono-Si, 19.0% to 18.0% for perovskite and 12.0% to 11.9% for DSSC.

Heat generation during the operation of the photovoltaic (PV) cell raises its temperature and results in reduced electrical output. The heat produced in the process can be removed by attaching phase change material (PCM) at the back of the PV panel which can contain the PV temperature substantially and increase its efficiency. Fins can be used inside the PCM container to enhance the heat transfer. In literature, it is observed that as soon as PCM is melted completely, the heat extraction rate of PCM reduces which again leads to increase in PV temperature. However, the study carrying out the optimization of Finned-PV-PCM system to keep PV temperature low during operation for different solar irradiance levels is not available in literature. Thus, in the current study, the most suitable depth of PCM container is calculated for different solar irradiance levels. In addition, how it is affected with spacing between successive fins, fin length and fin thickness has been studied. The best fin dimensions are also calculated. The results show that the most suitable depth of PCM container is 2.8 cm for ∑IT = 3 kWh/m2/day and 4.6 cm for ∑IT = 5 kWh/m2/day for the chosen parameters. The best spacing between successive fins (to keep PV temperature low) is 25 cm, best fin thickness is 2 mm and best fin length is the one when it touches the bottom of the container. PV, PV-PCM and Finned-PV-PCM systems are also compared. For PV-PCM system (without fins), the most suitable depth of PCM container is 2.3 cm for ∑IT = 3 kWh/m2/day and 3.9 cm for ∑IT = 5 kWh/m2/day.

The efficiency of solar cell is generally defined at standard test conditions. However, wind direction, wind velocity, tilt angle of panel and solar radiation during operation differ from those at standard test conditions. The effects of operating conditions on the temperature and efficiency of silicon solar cells are widely analysed in literature. In the current work, the thermal performance of perovskite and dye-sensitized solar cells in operating conditions has been analysed and compared with monocrystalline silicon solar cell. The effects of wind direction (wind azimuth angle), wind velocity, tilt angle of panel and solar radiation on the temperature and efficiency of the cells have been analysed. The results show that as wind azimuth angle increases from 0° to 90°, the temperature of the cell increases from 51.8 °C to 58.2 °C for monocrystalline silicon, from 45.5 °C to 50.7 °C for perovskite and from 48.4 °C to 53.9 °C for dye-sensitized solar cell and the corresponding efficiency of the cell decreases from 22.3% to 21.5% for monocrystalline silicon, from 20.1% to 19.5% for perovskite and from 11.8% to 11.7% for dye-sensitized solar cell.

The rise in the temperature of photovoltaic (PV) leads to decrease in the solar to electricity conversion efficiency. This paper presents a simulated study to investigate the thermal management of the PV panel using phase change material (PCM). It is found that once the PCM is fully melted, the rate of heat extraction by PCM decreases and, thus, the PV temperature starts increasing rapidly. In literature, the studies related to the performance analysis of the PV-PCM system are available. However, the optimization of the PCM quantity to cool the PV in various operating conditions and solar radiation levels is not available. Thus, it has been carried out in the presented work. The effects of the operating conditions (wind azimuth angle i.e. wind direction, wind velocity, melting temperature of PCM and ambient temperature) on the optimum depth of the PCM container have been analysed. The results show that as wind azimuth angle increases from 0° to 90°, the optimum depth of the PCM container (to maintain the PV at lower temperature) increases from 3.9 cm to 5.3 cm for ∑IT = 5 kWh/m2/day and from 2.4 cm to 3.2 cm for ∑IT = 3 kWh/m2/day for the chosen parameters.

Among all passive methods for photovoltaics (PV) cooling, phase change material (PCM) can be highly effective due to high latent heat capacity. However, very low thermal-conductivity of PCM restricts its potential. The proposed work focuses on the enhancement of rate of heat transfer from PV to PCM by using conductivity-enhancing-containers. The proposed approach was experimented outdoor and compared with the reference panel for different seasons at Chennai, India. PV temperature, open circuit voltage, short circuit current, Current-Voltage (I–V) and Power-Voltage (P–V) curves, fill-factors, power outputs, efficiency and daily electricity generation are reported. The results show that the proposed heat sink was able to decrease the maximum PV temperature from 64.4 °C to 46.4 °C for January and 77.1 °C to 53.8 °C for June. It increased the open circuit voltage of PV from 24.3 V to 26.4 V for January and 23.6 V to 26.0 V for June. The fill-factor increased from 0.678 to 0.705 for January. Consequently, the electrical efficiency increased from 9.5% to 10.5% during noon. Daily electricity generation increased from 769 Wh/day to 817 Wh/day during January and 948 Wh/day to 1026 Wh/day during June. Thus, daily electricity generation increased by 6.2% for January and 8.3% for June using proposed approach.

The intermittent nature of renewable sources, such as solar and wind, leads to the need for a hybrid renewable energy system (HRES) that can provide uninterrupted and reliable energy to a remote and off-grid location with the use of a biogas generator and battery. In the present study, conventional PV panels have been integrated with phase change material (PCM) for power enhancement. In addition, various configurations (i. PV-Wind-Battery system, ii. PV-PCM-WindBattery, iii. PV-Wind-Biogas-Battery and iv. PV-PCM-Wind-Biogas-Battery) have been compared for the hot and humid climatic location of Chennai, India. Optimization has been carried out to minimize the cost of energy and the net present cost has also been computed. It has been found that the integration of PCM with the PV-Wind-Biogas-Battery-based off-grid system results in savings of USD 0.22 million in terms of net present cost and reduces the cost of energy from USD 0.099/kWh to USD 0.094/kWh. Similarly, for another off-grid HRES configuration of PV-Wind-Battery, the integration of PCM results in savings of USD 0.17 million, and reduces the cost of energy from USD 0.12/kWh to USD 0.105/kWh.

Photovoltaic (PV) cells absorb the incident solar radiation while operation of which, majority part causes heating leading to the hampered electrical efficiency. PVs can be integrated with phase change material (PCM) to maintain cell temperature within desired limits and the effect can be improved by deploying fins. The current work aims at analysing the effect of climate on the electrical performance of finned PCM integrated PV. Modelling of system has been done which has been validated using experimental results. For the study, fins with various spacings, thicknesses and lengths are used. The main conclusions of the study are, (a) for less alterative climate, the improvement in the PV electrical output (using finned PCM) is 9.7%, 10.8%, 11.3%, 11.6% and 11.6% respectively for a spacing of 1 m, 1/2 m, 1/3 m, 1/4 m and 1/5 m. For highly alterative climate, the respective values reduce to 6.6%, 7.6%, 8.1%, 8.4% and 8.4%, (b) for warmer climate, the output increases by 10.1%, 11.3%, 11.8%, 12.1% and 12.1% while for colder climate, it increases only by 5.4%, 6.1%, 6.5%, 6.7% and 6.7%, (c) for windy climate, the power increments are significantly lesser as compared to the other case, (d) climate having higher wind azimuth results in better performance of finned PCM, and (e) for clear sky climate, performance of finned PCM is better.