Factors Affecting Solar PV Performance Abstract: The output of the photovoltaic solar array (PV) is not constant throughout the day. This is different from time to time. Change in output with climatic conditions, varies in winter and rainy season.
So we cannot maximize output all the time. This paper discusses the factors that affect the performance of solar PV in different environmental conditions and the location of PV modules. These factors may be the orientation of PV modules, sunlight tracking, PV temperature modules, slope angle / slope of PV panels, shade panels, roofing materials, solar irradiation, PV module type, and dust on the module. Above words are some important factors that significantly affect performance photovoltaic solar cells.
So it needs to be discussed. Introduction. Solar energy is most readily available source of energy. It is Non-polluting and maintenance free. To make best use of the solar PV systems the output is maximized by suitable methods. For this PV solar cell is used that uses PN junction to directly convert the sunlight into electricity. The voltage and current both are the function of light falling on this. But too much isolation of the cell cause the saturation eventually the power output reduced because of increase in mobility of electron and increase in temperature.
The other problem is tracking of the sun according to the PV module i.e. orienting the panel in such a direction so that panel receives maximum irradiance.
MPPT is important parameter to be considered for power output of panel. Irradiance falling on the surface is not constant all the time due to fluctuation of environmental condition temperature change and irradiance level changes. Due to this IV curve changes and hence MPP algorithm keeps on tracking the knee point in IV curve. Like this there are many problems faced by already installed PV panel. This paper will review the paper on which work is already done. FACTORS AFFECTING THE PV MODULE PERFORMANCEA. Solar radiation: Irradiation is the measure of solar energy density received at a location on earth due to fluctuations environmental conditions, temperature changes and hence The rate of radiation changes and is measured in watts per meter box. While irradiation is a measure of energy density of sunlight.
The term irradiation and irradiation is associated with solar components. As the sun’s isolation continues changed all day so I-V and P-V characteristics vary. With increasing solar radiation both open circuits the voltage and current of the short circuit increases and hence the maximum power point varies. A temperature is another major factor in determining solar cells efficiency. The cell voltage is reduced by 2.2Mv per degree temperature rise 3. I-VCharacteristics The I-V Characteristics is a curve between current and voltage.The area under the I-V curve shows the maximum power that is produce underoperating at maximum current and maximum voltage.
The area decreases withincrease in solar cell voltage due to its increase in temperature.Fig.1Dark and irradiated characteristicsThe maximum power point can be obtained by plotting thehyperbola defined by V*I= constant. Abservation table:The performance of PV modules is obtained at different irradiance level and intensity. For this above two observations are taken. For radiation and voltage intensity, current and power are calculated and for a given maximum power voltage is obtained. That the corresponding IV characteristics are shown above show Pmax for different radiation levels.
More irradiation the more power output of PV module is.Fig.2Shows the current vs voltage curve at various irradiance levels and thecorresponding maximum power points.An example is mentioned on paper 3. There is one point on the indentation that will generate maximum power below the level of illumination incidents Operating elsewhere another point then maximum power will mean that cell will produce maximum thermal power and less electrical power.
MPPTThe voltage at which the PV module can produce maximum power is called the maximum power point. MPPT checking output of PV module and compare with battery voltage then fix what the best power PV modules can do produce to charge the battery. Basically MPPT is dc-dc converters that operate by taking dc to PV modules convert it to ac and then convert to different dc voltage and the current to exactly match the PV module to the battery. MPPT uses a buck or boost converter for operation.
B. TemperatureTemperature plays a major factor in determining efficiency of solar cells. As temperatures rises the rate of generation of photons increases so as to reverse saturation It is currently increasing rapidly and this reduces band gap.
Therefore, this leads to the current but major marginal voltage changes Cell voltage decreases 2.2Mv per degree of temperature rise. These results are experimental proven . Here the temperature acts as negative factors affecting the performance of solar PV.
Temperature modules should be maintained at room temperaturein several ways. Solar cells perform better in the cold than in heat climate panels rated 25 ° C. In the summer days temperatures can easily reach 70 ° C or more that means it panel will produce 25% less power compared to it rated 25 ° C so the 100 watt panel produces only 75watts in May / June in most of Pakistan. Solar pannels are tested at STC with irradiance level of 1000W/m2 and 25°C but in real world condition are constantly changing.Observation Table:Fig.3Shows the effects on the current and voltage. C. Incident AngleTocheck the effect of incident light on the voltage generated an experiment wasperformed in USPCAS-E Peshawar lab and the following values were noted.
Observations: This experiment data shows that short circuitvoltage increases with increase in the angle of incidence upto 90 degree whereit becomes maximum and after that as we further the increase the of incident oflight the short circuit voltage start decreasing. We also noted that the changein the short circuit voltage is quite small.D.
ShadingWhen choosing a roof area for photovoltaic arrays, Efforts should always be made to avoid shading or area known for the accumulation of substances that will produce Shading. Cell shading is another very important factor drastically affect the performance of PV modules. Solar PV fibers often experience partial and rapid shading shade fluctuations. Fast fluctuations in shading Patterns make tracking of maximum power points hard.There will be some local MPP and its value will occur change as fast as lightning.
Shade PV modules can be done by trees, large buildings construction structures around it. This can cause partial or full shade. More shading effect on Conventional configuration (PV module connected series) than parallel. A very parallel PV system which operate effectively quickly and easily condition. PV modules instead of PV cells connected in paralleland shown to show better performance in shade condition 6,7.
Each PV module is treated as a single unit which tracks the MPP itself. Therefore, while the module is on Shaded, the degradation of its performance will not propagate to other modules.Fig.4shows the curve for the effect of shading on terminal voltage.Shading mainly affects the circuit connected PV module.
Because the current generated by the shaded part is less than compared to the illuminated part. But this time the series Must be the same cells illuminated at this time forcibly shady section of the current to improve the hotspot results and can cause damage of all modules to solve this problem Parallel configuration is used to set the PV module. In parallel the output is not so affected as in the case of the series configuration. Because the current in parallel is not the same All panels but the voltage must be the same. This experimental prove that parallel configuration is better of the series.
CONCLUSIONThis paper review the analysis of thework performed related with the PV module. The factors discussed in this paperare very important that affect the performance of the PV panel. If these factorare not considered in installation and working of panel it may drasticallyreduce the electrical output power which result in the loss of capital investedin the project. If these factors are taken care the output and capacity of thesolar power sector can be improved in our country. It is seen that irradiance,temperature, orientation, tilt angle, shading, dusts are some major factoraffecting panel performance. So adequate technique should be developed tomitigate these problems. References:1)UspcaseLab Peshawar.
2) LijunGao, Senior Member, IEEE, Roger A. Dougal, Senior Member, IEEE,”Parallel-Connected Solar PV System to Address Partial and Rapidly FluctuatingShadow Conditions”, volume:56, issue:5,Publication Year: 2009 , Page(s): 1548 –15563) Journal of Solar EnergyVolume 2013 (2013), Article ID 734581,http://dx.doi.org/10.1155/2013/734581 4) Pradhan Arjyadhara1, Ali S.M2, Jena Chitralekha3, “Analysis of SolarPV cell Performance with Changing Irradiance and Temperature” ,1 Jan 2013 PageNo.
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