How can sun spots disturb power grids?

The sun puts out a lot of electromagnetic radiation and lots of charged particles. Sunspots indicate solar activity and what are called "prominences" which are gigantic magnetic fluxes coming off of the surface. Sometimes the magnetic fluxes can be so large that the sun does not hold on to them, and they are ejected. We are shielded from most of the highly charged particles that come our way by earth's natural magnetic field. Some of the particles are drawn in by the field, and that's what auroras are.

Anyway, a huge coronal ejection (one of those big magnetic fluxes) directed toward earth could push the earth's magnetic field inward, and the ejected solar magnetic field would screw with our power. Electricity and magnetism are very very connected. It has to do with the behavior and movement of electrons. Have you ever held a magnet to an older TV? Notice how it bends the image? That's because it's pulling on the electrons. Electricity is simply electrons moving along a circuit. If a magnet that attracts electrons more strongly than the conductor is put close to a power line, then the electrons will be drawn away from the line and toward the magnet, and it will locally disturb the power. That's what could happen with the sun, only on a much bigger scale.