**2. Equivalent circuit of photovoltaic cell**

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]. Other models include two diodes as in figure 1d, [7] and [8].

photovoltaic cell or module when measuring the voltage if not flowing current (current of 0 amps), *PMAX* (Maximum power) is maximum power that can generate a photovoltaic cell or module and it's the product of maximum voltage and current, *VMAX* (Maximum Voltage) is the voltage at maximum power (around 80% of open circuit voltage) and *IMAX* (Maximum

Modeling of Photovoltaic Cell Using Free Software Application for Training and Design Circuit in Photovoltaic...

http://dx.doi.org/10.5772/51925

123

Compare the figure 2 with equivalent circuit (figure 1b), value of *ISC* related with *IL* and val‐ ue of *VOC* related with voltage and current diode (*Id*). Then diode includes effects of expo‐ nential of I-V curve. Finally *Rs* adjusts value of *PMAX*. All parameter information is extract to datasheets, and *SCM* are: *25ºC* for cell temperature (*TC*), *1000 W/m2* for irradiance (*G*), *1,*5 for

Reference to the circuit of figure 1c, then show all equations needed to obtain all the parame‐ ters 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 pho‐ tovoltaic cell, *V* is output voltage of photovoltaic cell, *IL* is the photogenerated current, *I0* is the saturation current of diode, *RS* is series resistance due to the junction between the semi‐

Current) is the current at maximum power.

**Figure 2.** IV Curve of photovoltaic module

spectrum solar and *3m/s* for wind speed.

**4. Modeling equations of photovoltaic cell**

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 calcu‐ lated parameters using data from the photovoltaic cell indicated in datasheets, for equiva‐ lent circuit on*figure 1c*.

**Figure 1.** Equivalents circuits of photovoltaic cell
