In this module, we'll talk about silicon solar cells. You've already, of course, heard of silicon solar cells. They were invented in the 1950s. They were the first of commercially available solar cell technology. They still dominate the market. You know they were used in the early space applications which really carried the developments of them. In this module, we'll talk a lot more about silicon solar cells, how they work and how they are produced and so on. Well, let's dig into it. So first I'd like you to meet an expert here from DTU. He's called Russell Smith Ericsson. He works at DTU Nanotech. We started investigating silicon solar cells back in the 50s and in the 70s came the first commercial systems. So some of them are actually still out there in the field today, so when it comes to reliability and how silicon cells and panels withstand the time and the affect of the external environment, we actually have a pretty good idea because we have empirical data from the late 70s. You know the silicon solar cells were invented in the 1950s and they, sort of, became commercially successful really in the 1970s. So the obvious question is now, why do we use silicon solar cells? Silicon is the most abundant semiconductor material we have available here on Earth. It's the second most abundant material in the earth's crust after oxygen. So silicon is very abundant and the band gap of silicon as a semiconductor is quite appropriate for portable tanks for solar cells. So just to iterate, we, of course, use silicon solar cells because there's abundant silicon available. Secondly, it has a very suitable band gap for solar cells. And the third reason is that there's a big overlap between the electronics industries. So we use silicon in transistors and integrated circuits and so on. During the module we'll talk about various subjects. First of all we'll talk about how do silicon solar cells work. We'll talk about how they are produced going through all of the different steps in their production and we'll actually go as far back as say, how to actually make the silicon that's required, because it has a few implications on especially the energy payback time of silicon solar cells. We'll also review the potential of silicon solar cells and talk about if they'll keep up their place in the market, being a dominant solar cell technology.