Solar Cells Simulation - Part 1: Theory
Introduction
Hello everyone! Today, I'm going to discuss solar cell simulation using numerical tools, focusing on the fundamental aspects. My name is Majid, and I hold a PhD in photonics. I am currently working at Ozen Engineering, Inc., where we specialize in the simulation of optics and photonics, structural, thermal, fluid, and electromagnetic fields. We offer consulting, training, mentorship, and technical support, and we also provide ANSYS software tools.
ANSYS Lumerical
ANSYS Lumerical offers a broad range of applications, as shown in the slide. It covers:
- Circuit simulation, including numerical engineering, interconnect, quantum interconnect, photonic Verilog-A, and compact model compiler.
- Component-level solutions, depending on the application needs. For example, in solar cell applications, we use numerical FDTD, charge, and heat simulations.
We start with numerical FDTD to simulate optical parameters, and then use heat and charge simulations to study heat and charge distribution, which I will describe in the following slides.
Planar Silicon Solar Cell Simulation
For the planar silicon solar cell, we use FDTD, charge, and heat simulations to model a 1D planar silicon solar cell. The key performance metrics in solar cell simulation include:
- Short circuit current
- Fill factor
- Open circuit voltage
- Photovoltaic efficiency
Workflow of Solar Cell Simulation
The workflow begins with numerical FDTD to calculate optical and heat generation. The heat output is directed to the heat sensor, then to the heat solver, where we extract the temperature profile. The optical generation data is sent to the numerical charge simulation to calculate various parameters such as efficiency, short circuit current, open circuit voltage, and fill factor.
Physics Behind the Solver
The solver is based on three key equations:
- Current Density Equation: This involves understanding drift and diffusion. The drift current depends on the electric field, with mun and mup representing the mobility of electrons and holes, respectively. Diffusion depends on the non-uniform distribution of electrons, a material property, allowing us to calculate current density.
- Continuity Equation: Charge is a conserved quantity, meaning the total charge inside a volume V changes only when charge flows through the boundary surface. This equation connects current density and total charge, incorporating drift, diffusion, recombination, and generation.
- Poisson's Equation: This relates the density of electric charge to the electric potential. Donor and acceptor impurities (A) are injected into the semiconductor, affecting the doping density.
Solar Energy and AM 1.5
For solar energy, we use AM 1.5, indicating sunlight radiating through the atmosphere at an angle of 41.8 degrees above the horizon. The spectrum of solar energy is compared to black body radiation, governed by specific equations. Spectral irradiance is lower than black body radiation due to atmospheric absorption.
This concludes the theoretical discussion of solar cell simulation. Thank you for your attention!
Title: Solar Cells Simulation - Part 1: Theory Hi everybody. Today I'm going to talk about solar cell simulation with numerical tools, specifically the fundamental part. I'm Majid, and I hold a PhD in photonics.
I work at Ozen Engineering, where we are experts in simulation of optics and photonics, structural, thermal, fluid, and electromagnetic fields. We offer consulting, training, mentorship, and technical support, as well as ANSYS software tools.
ANSYS Lumerical provides us with a broad range of applications, including circuit simulation, numerical engineering, interconnect, quantum interconnect, photonic VRLogA, and compact model compiler. At the component level, ANSYS Lumerical provides solutions for various applications.
For solar cell applications, we use numerical FDD and charge and heat. We start with numerical FDD to simulate optical parameters and then use heat and charge to study heat and charge distribution.
For a planar silicon solar cell, we use FDD, charge, and heat to simulate a 1D planar silicon solar cell. The key performance figure of Merit in solar cell simulation is short circuit current, fill factor, open circuit voltage, and photovoltaic efficiency.
The workflow of solar cell simulation involves starting with numerical FDD to calculate optical and heat generation. The output of heat goes to the heat sensor, and then the heat goes to the heat solver.
In the heat solver, we extract the temperature profile and the optical generation goes to the numerical charge. We can calculate different parameters, such as efficiency, short circuit current, open circuit voltage, and fill factor. The physics behind this solver involves three equations.
The first is the current density equation, which consists of drift and diffusion. The drift equation depends on the electric field, and the mu n and mu p are the mobility of electrons and holes. The second part is diffusion, which depends on the non-uniformity distribution of all electrons.
The second equation is the continuity equation, which states that charge is a conserved quantity. The third equation is the poison equation, which states that the density of electric charge depends on the electric potential.
For solar energy, we use m1 am 1.5, which indicates that the sunlight is radiating through the atmosphere at an angle of 441.8 degrees above the horizon. We consider this solar energy spectrum in our calculation and compare it to black body radiation, governed by specific equations.
The spectral irradiance is lower than the black body radiation because the sun's light comes from the atmosphere. The Klein line should be labeled as "dry."
