The Environmental Engineering Hub

In this final introduction post on photovoltaic energy conversion, we will discuss the various parts of a solar cell and the losses that occur in a solar cell. The losses in solar cells will provide an important framework to put everything we learn over the course of the next couple of weeks in context .The learning objective for this post are to understand the main function of the various parts of a solar cell. We will discuss the main losses that occur in solar cells and we will come to understand how these losses lead to the design rules for solar cells. Shown here is a standard silicon wafer based solar cell. These are the most common type of solar cells, accounting for about 93 % of the total production in 2015. We will base this solar cell on a p-type silicon absorber even though some silicon cells can be made with an n-type absorber layer. The purpose of this absorber layer, as its name implies, is to absorb light. Through this absorption, minority and majority charge c...

In our previous postwe learned about the i-V characteristic of a solar cell. How can we simulate this characteristic in a circuit diagram? To answer this question we are going to look at the equivalent circuit of a solar cell. Let’s start with what we learned in the previous video. Here is the I-V characteristic of a solar cell. We can note the V_OC and I_SC that we described before. We can notice a few things about this plot. There is an exponential characteristic, and it is offset negatively somehow. So how can we represent this as a circuit model? Those of you with an electrical engineering background may already realize that this resembles the characteristic of a diode, and that is exactly correct. A solar cell is, in fact a diode, and if the solar cell were in the dark, it would act, electrically, just like any other diode. However, illumination of the solar cell is what offsets it as we see here. So let’s take a look at how to model this electrically.  ...