I discuss the impact that shunt resistance and recombination losses can have on module energy ratings. Shunt resistances of cells in a two‐terminal, series‐connected photovoltaic module can affect module power output as well as indicate flawed manufacturing processes and reliability problems. A two‐terminal diagnostic method to directly measure the shunt resistance of the individual cells within a series‐connected module non‐intrusively, without the need of de‐encapsulation is discussed.