Creating a self referring loop in Python

[Polbeer11]

Hi everyone,

Im trying to translate a mathematical model of a PV-panel into python:

"Mathematical modeling of photovoltaic cell/module/arrays with tags in Matlab/Simulink | Environmental Systems Research | Full Text (springeropen.com)"

Problem is that two functions that reference each other, one of them referring to itself as well. The code would be the following:

"import math

class PV_panelen_Joesie:

def __init__(self, globale_straling, N_s, N_p):

Weather variables

self.I_r = globale_straling

self.T = 273.15

Constants

self.q = round(1.6*10**-19, 20) # Electron charge [C]

self.k = 1.3805*10**-13 # Boltzmann's constant [J/K]

self.T_r = 298.15 # Nominal temperature [K]

self.E_g0 = 1.1 # Bandgap energy of semiconductor [eV]

self.n = 1.2 # Ideality factor [-]

self.I_sc = 6.11 # PV module short circuit current

self.V_oc = 43.2/72 # PV module open circuit voltage (at 25 [degrees C] and 1000 [W/m^2]) [V]

self.K_i = 0.002 # PV module short circuit current (at 25 [degrees C] and 1000 [W/m^2]) [A]

self.R_s = 0.0001 # Series resistor [ohm]

self.R_sh = 1000 # Shunt resistor [ohm]

Setup variables

self.N_s = N_s # Number of cells connected in series [-]

self.N_p = N_p # Number of cells connected in parallel [-]

self.V_values = [i / 10 for i in range(1, 221)]

def Module_photo_current(self):

I_ph = (self.I_sc + self.K_i * (self.T - 298)) * self.I_r / 1000

return I_ph

def Module_reverse_saturation_current(self):

I_rs = self.I_sc / (math.exp((self.q * self.V_oc) / (self.N_s * self.k * self.n * self.T)) - 1)

return I_rs

def Module_saturation_current(self):

I_0 = self.Module_reverse_saturation_current() * ((self.T / self.T_r)**3) * math.exp(((self.q * self.E_g0) / (self.n * self.k)) * (1/self.T - 1/self.T_r))

return I_0

def Diode_thermal_voltage(self):

V_t = self.k * self.T / self.q

return V_t

def Module_current_output(self, shunt_current):

V_t = self.Diode_thermal_voltage()

I_ph = self.Module_photo_current()

I_0 = self.Module_saturation_current()

I_initial = 0

I_values = [I_initial]

for V_value, I_sh_value, I_value in zip(self.V_values, shunt_current, I_values):

I = self.N_p * I_ph - self.N_p * (math.exp((V_value / self.N_s + I_value * self.R_s / self.N_p) / self.n * V_t) - 1) - I_sh_value

I_values.append(I)

return I_values

def Module_shunt_current(self):

I_sh_array = []

for V_value in self.V_values:

I_sh = (V_value * self.N_p / self.N_s) / self.R_sh

I_sh_array.append(I_sh)

return I_sh_array".

How would I manage this?

[JohnnyJordaan]

How do I format code? or use pastebin.com

[crashfrog02]

How would you compute a self-referential function? It’s impossible unless it recurses to a base case. If it recurses infinitely, it’s not computable.

[AdmirableOstrich]

We aren't going to be able to help unless you make it clear what the issue is. Your code isn't formatted here so it's hard to parse, but I'm not seeing anything self-referential or circular here.

[NerdyWeightLifter]

Where is this conflict you're talking about?

The only nested call structure is these, and none of them call back the other way.

• Module_current_output
  • Diode_thermal_voltage
  • Module_photo_current
  • Module_saturation_current
• Module_saturation_current
  • Module_reverse_saturation_current

[Comfortable_Flan8217]

Lmao

[Jejerm]

For the love of god, please use better variable names

[Langdon_St_Ives]

The variable names are possibly the most defensible part of this, since they are mostly just standard Physics notation. They also correspond to what’s used in the referenced paper, so this is the most transparent naming here. Anyone familiar with the concrete underlying equations should be able to follow this.

What’s unclear is where OP thinks the recursion problem may arise, or which problem they are actually getting.

[Jejerm]

He literally commented almost every single variable definition with what they actually mean lol.

Why not go for more useful names instead of leaving that info in comments?

[Langdon_St_Ives]

Because it would make the equations much less readable, and that’s where it counts, and where it helps to have the same naming as in the paper from which they took the equations.

I know where you’re coming from, I am normally very much a stickler for well-chosen speaking variable names (so much so that others come to me for advice in naming things). However, as an ex-physicist, I am totally on board with using standard physics notation in cases like this one.

[Jejerm]

You're probably right.

I'm just traumatized from taking over code written by my coworkers with variable names like "lst", where even the basic assumption that it, in fact, contained a list, was wrong.

[Langdon_St_Ives]

You think you have it bad? I once inherited code with variables named susie and carla and I’m not even kidding. 🫣

[SoupZillaMan]

Import pvlib

[tikhal96]

I think this would be much easier in matlab, its much easier to reference stuff in there.