What other kinds of solar power are there besides rooftop systems?

Solar power systems generally come in two kinds, photovoltaic arrays, like the one on our roof, and solar thermal systems, which generate power from the heat of the sun.

Both kinds of systems can be enhanced by concentrating the solar energy with mirrors and lenses onto a single, small area.

The most common alternative to photovoltaic systems, are thermal systems that concentrate solar energy onto a conduit, and inside the conduit is something that conducts heat, often some kind of oil. The conductor heats up and is then used to boil water, which creates steam, which operates turbines, that generate electricity.

That is all quite complicated compared to the relative simplicity of direct electricity from the sun through photovoltaic panels.

However, solar thermal can produce an enormous amount of power. Currently, the largest solar power plant in the world is a 354 megawatt solar thermal plant in California’s Mojave desert.

Solar thermal power plants are also the only kind that can produce power 24 hours a day, so far. These systems use the sun’s energy to heat salt to the point where it turns into a molten liquid. The molten salt is then stored in an insulated container, and its heat can be used around the clock to drive turbines and create electricity. The Gemasolar plant near Seville, Spain, was the first commercial plant in the world to achieve this, in the summer of 2011.

In Modesto, California, there is a solar thermal powered factory making Sun Chips snacks. In this case, the solar thermal system heats water which is used to make steam that helps cook the ingredients for the chips.