Real World Efficiency Limits: the Shockley–Queisser Model as a Starting Point
We survey published experimental data on the performance of cells and modules to compare all types of today's solar cells and with these find solar cell efficiencies that we can strive towards. Such an approach allows identifying limits that need to be considered for real solar cells on top of the Shockley–Queisser (S-Q) limit, as the latter applies strictly to an ideal model system. Prominent among the additional limits is the degree of disorder of the absorber, strongest for amorphous Si-based cells, and minimal for II–V-based cells (and hopefully, for the new perovskite ones). While adding extra limits lead to lower numbers than the S-Q ones, normally used, the results help us to see what we can hope to reach in practice, in terms of technological progress and in terms of champion cells.