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Download preview PDF. Skip to main content. Advertisement Hide. Solar Radiation Devices and Collectors. This process is experimental and the keywords may be updated as the learning algorithm improves. This is a preview of subscription content, log in to check access. This model can be used for training in photovoltaic solar energy, using: subcircuits, curves, tables and equations. Further, can be used an attractive presentation to the student with a real representation of PV cell. Also, can be used to test circuit with photovoltaic solar cell as power supply, in applications such as: micropower systems for harvesting energy, stand alone PV system for control battery charge.

The model of PV cell can be used to simulate a PV module, because PV module is an association of cells in series and parallel.

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The model PV module can use to study mismatch effects due to different electrical characteristics of PV cells and the use of pass diode to reduce loss due to partial shadows. Then, can be use PV module study PV grid connection and energy production prediction. The equivalent circuit of an ideal cell is formed by a current source in parallel with a diode figure 1a. There are several circuits that include resistors for real effects of a photovoltaic cell, for example, figure 1b includes a resistor in series, [ 2 ], figure 1c includes parallel and series resistance, [ 1 ] and [ 6 ].

### 1st Edition

Other models include two diodes as in figure 1d, [ 7 ] and [ 8 ]. The circuit of figure 1c is the more commonly used, although in several simulations simplifies the parallel resistance value with a high value, using the series resistance to include effect of fill factor, gets a similar circuit of figure 1d and used Rp to avoid problem with simulation. Then, this circuit has a simple and accurate model to simulate a photovoltaic cell. The problem is the parameter values of circuit components.

Therefore, in Section 4 are calculated parameters using data from the photovoltaic cell indicated in datasheets, for equivalent circuit on figure 1c. Calculate equivalent circuit parameters need to know the I-V curve. Then diode includes effects of exponential of I-V curve.

Reference to the circuit of figure 1c, then show all equations needed to obtain all the parameters that define the model in standard conditions of measurement SCM. In equation 1 shows the intensity value generated by the photovoltaic cell, [ 9 ]: I is output current of photovoltaic cell, V is output voltage of photovoltaic cell, I L is the photogenerated current, I 0 is the saturation current of diode, R S is series resistance due to the junction between the semiconductor and the metal contacts interconnects , R P is parallel resistance due to no linearity of union PN , m is ideal factor of diode and Vt is thermovoltage shown in equation 2 where: k is the Boltzmann constant, q is the electron charge and T is temperature in degree Kelvin.

Then we obtain the equation 3 at SCM. Then, needs calculate fill factor of ideal device FF 0 at equation 5 , using parameter voc of equation 6 , and calculate R S using equation 8. The fill factor FF of photovoltaic cell shows at equation 7. This approach only use when R P is high, therefore fill factor depends of R S value. The datasheet used parameters of table 1 , establishing the relationship between units voltage, current and power and temperature. Temperature can be expressed on degree Celsius or Kelvin, depends of manufacturer. The relationship between temperature ambient T A and cell T C , can used equations 1 1 and 12 , [ 11 ].

Use this approximation is interesting because there are statistics of temperature ambient on geographic situation but temperature cell depends to PV cell and module.

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Figure 3 shows the simulation window with all the necessary equations and the visualization of results using QUCS. QUCS allows represented on the same page a circuit and results of simulation, for example in figure 3 included: IV Curve , output power curve, output current curve, output voltage curve and a table with numerical results. For functions used in QUCS see on [ 13 ], in figure 3 used following equations: eqn1 for parameters of photovoltaic cell, eqn2 for change temperature ambient to cell temperature, eqn3 for parameters adjust to equivalent circuit and eqn4 to calculate variables to represented results on graphical depends to output measurement of equivalent circuit.

The equivalent circuit is formed by following components: current source dc current source on source library , diode diode on non linear components library and resistors resistor on lumped components library. The value of current source is calculate on variable IL current generate on equ3 based on equation 9 , the value of current saturation on diode is calculate on variable I0 on equ3 based on equation 10 , the value of resistor series and parallel its calculate manually and indicate on eqn3. Current measurement of PV cell model used current probe Icell on probe library, for voltage measurement used a wire label Vcell to get voltage on node.

Power generate Pcell of PV cell is calculates using equ4 as the product of current Icell.

## Solar Radiation Devices and Collectors

I and voltage Vcell. V measurement. The results on simulation show on graphical Cartesian on diagrams library and table Tabular on diagrams library. In QUCS is a used component of library simulations for configuring simulation, for example to get IV curve need components: dc simulation and parameter sweep figure 4. Also, if changes value of Irradiance variable on eqn2 figure 3 , changes the solar condition and current generate of PV cell.

Further, if changes value Tamb variable on eqn2 figure3 , change ambient temperature and therefore the cell temperature condition based on equations 1 0 and Then, combining the two variables can adjust weather conditions. The model shown in Section 4 can be used for the formation of PV system. In particular, using subcircuit for an attractive presentation for the student, [ 10 ].

In addition to evaluating the effects of: association series and parallel, potential losses, weather conditions, non-ideality of photovoltaic cells and effect of partial shadow. Figure 7 shows steps for modelling by subcircuits of a PV cell and module, first represented a equivalent circuit and include parameters gets of datasheet, second create a symbol to represented a PV cell, third the subcircuit used to external variables for irradiance G and cell temperature Tc , fourth associate cells to build a PV module, and finally create a symbol to represented a PV module.

To create a subcircuit needs connection for output PV cell, after to select all component of equivalent circuit figure 3 the output connection of PV cell in series with Rs for positive connection connects used insert port figure 8. Once finish equivalent circuit can be edit representation of subcircuit pressing F9 , for edit representation can be used painting library, [ 13 ].

Model for PV module can be create using PV cell subcircuit and connection in series and parallel, for example a PV module for 12V nominal voltage can be formed by 36 PV cells connects in series, in figure 9 shows connections of PV module with 2 pass diodes and external ports connections positive for P1 and negative for P2. Representation used for PV cell and module shows on figure 7 , after can be used subcircuit of PV cell or module on different practices. Then, student works directly with subcicuits independently of equivalent circuit model, because student can be used the same representation for different PV cells.

The practices developed show in table 2 , for study for photovoltaic training on stage generation, after can be complete with model of all components on photovoltaic system battery, regulator or inverter and can be used on renewable energy training. Practices on table 2 can be complete with a previous work: select values for equivalent circuit and introduction of QUCS. Figure 10 shows several examples for use subcircuits model for educational, and are directly applicable to any practices described.

## External publications | ISES

Solar radiation -- Mathematical models. Solar radiation -- Measurement. Summary Written by a leading scientist with over 35 years of experience working at the National Renewable Energy Laboratory NREL , Solar Radiation: Practical Modeling for Renewable Energy Applications brings together the most widely used, easily implemented concepts and models for estimating broadband and spectral solar radiation data. The author addresses various technical and practical questions about the accuracy of solar radiation measurements and modeling.

While the focus is on engineering models and results, the book does review the fundamentals of solar radiation modeling and solar radiation m. Notes Description based upon print version of record.

## Solar Radiation: Practical Modeling for Renewable Energy Applications

Includes bibliographical references and index. View online Borrow Buy Freely available Show 0 more links None of your libraries hold this item. Found at these bookshops Searching - please wait