Part of my Physics Planning paper says this: "You are to design laboratory experiments to compare the energy conversion rates of the two systems (one using photons to release electrons in a solar cell and one using a solar panel to heat water), in order to find out which is the more efficient. The energy source should be a standard 150W light bulb connected to the 230V mains. What does the phrase in bold mean? Surely the bulb wouldn't be connected to the mains, it would be connected to the solar cell which I am testing right? Or am I being totally dense?