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Subject: search.filters.subject.Irradiance

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    Maximum power point modeling through irradiance-based duty cycle calculation
    (EUPVSEC, 2016) Kumar, Rajneesh
    This paper proposes an irradiance based modeling of duty cycle, for maximum power point operation of a panel. In existing methods for irradiance prediction, a relation was established to input maximum power duty cycle with parameters of panel. Proposed system operated with better maximum power point based on panel parameters duty cycle relation. Duty cycle of the converter is independent of feedback from output side so that the necessity of voltage sensing was eliminated and duty cycle input to converter was calculated from irradiance input on panel. Irradiance data for last 10 years was collected from NASA’s website and for various level of irradiance Vmp, Imp are modeled to ensure maximum output power from converter. Duty cycle is then calculated with converter topology to trigger switch. Modeling of proposed system was done with different irradiance levels to calculate duty cycle for a year. Then obtained model was verified at predicted irradiance levels and a maximum point operation up to 98.21% was obtained. In various parameters of solar panel maximum power voltage, maximum power current and load side impedance was taken for duty cycle calculation. This proposed research work based on input effective resistance and output resistance is useful in constant voltage demand applications like battery charging or to supply constant dc load
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    Modeling of soiled PV module with neural networks and regression using particle size composition
    (Elsevier, 2016-01) Kumar, Rajneesh
    Particle size composition of the soil accumulated on a photovoltaic module influences its power output. It is therefore crucial to understand, quantify and model this soiling phenomenon with respect to particle size composition for predicting soiling losses. Five different soil samples from Shekhawati region in India are collected and relative percentage of standard particle sizes which are 2.36 mm, 1.18 mm, 600 μm, 300 μm, 150 μm, 75 μm and less than 75 μm are determined from sieve analysis. In order to understand and quantify the soiling effect, regression model is developed and to predict the power loss at various levels of irradiances, neural networks model is developed from the obtained experimental data. These models were compared and validated for the power output obtained at wide range of irradiance levels. It was concluded that regression can be used to analyze and quantify the particle size influence on the soiling losses of a PV module while neural networks are efficient in predicting the power output of a soiled panel. It was also observed that influence of 75 μm and lesser size particles is predominant on the power output at low irradiance levels (300–500 W/m2) while it is the 150 μm particle size that impact the power output at higher levels of irradiance (1000–1200 W/m2).
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    Analysis of irradiance losses on a soiled photovoltaic panel using contours
    (Elsevier, 2016-05) Kumar, Rajneesh
    This paper introduces an irradiance loss factor that quantifies the relationship between irradiance, tilt angle and power output of a soiled panel with the soil particle size composition. Artificial soiling experiments were performed using four soil samples at irradiance levels between 200 and 1200 W/m2 at 18 tilt angles. Biharmonic interpolation was used to develop power contours in terms of irradiance and tilt angle from experimentally obtained data. These contours were compared with ideal ones of a clean panel to observe deviation in the nature of contours for a soiled panel. A correction factor in terms of particle size composition (as a coefficient to tilt angle) was proposed to calculate power output of a tilted soiled panel. The angular loss on a panel with soil sample containing 150 μm particle size in abundance was observed to be 22% and for sample containing 75 μm particles in majority, the loss is 24%. Presence of 300 μm particle size in abundance causes a 23.7% loss, while 52% angular loss was observed for soil with highest composition of less than 75 μm particle size.
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    Characterization of power losses of a soiled PV panel in Shekhawati region of India
    (Elsevier, 2016-06) Kumar, Rajneesh
    This paper introduces a model that quantifies the relationship between power output, incident irradiance and soil particle size composition of soiled photovoltaic panels. Soil samples used in artificial soiling experiments were collected from Shekhawati region in India and their relative percentage of standard particle sizes is determined from sieve analysis. A non-linear relationship between irradiance and power is obtained using regression analysis showing the effect of particle size composition present on the panel. Further, the tilt angle for maximum power extraction is determined for each soiled panel and the deviation from the optimum tilt angle of a clean panel is observed. It is concluded that, when the soil present on the panel is rich in the particles with diameter (75 μm and below), the deviation from the tilt angle of a clean panel is 4°, however if the soil contains higher composition of both 150 μm and 300 μm particle sizes the deviation is 8°.
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    A proposed maximum power point operating strategy for photovoltaic applications using monthly irradiance estimates
    (Elsevier, 2017-01) Kumar, Rajneesh
    In this paper, we propose a new application of irradiance estimate for photovoltaic (PV) applications. Maximum power point (MPP) operating strategy for PV system is developed using monthly irradiance estimate based duty cycle control. Duty cycle of DC-DC converter is calculated using monthly average irradiance (Gav) and average of maximum irradiance (Gmax,av) received at Pilani during 2002–2011. Designed PV system operates at 60–95% of MPP throughout the year with these monthly irradiances based duty cycle operations. MPP of 71.6% and 66.81% is observed for January and July months respectively when the model is validated for weighted mean of maximum power point (wMPP) operation. Further, a % MPP of 98.21 is achieved when proposed strategy is tested at short interval irradiance estimate based duty cycle control. Extensive simulation using MATLAB/SIMULINK is carried out to observe the operating points of PV system under dynamic changing irradiances levels. Experiments using solar array simulator (SAS) are performed to validate the simulated results.