Flares are known to be cyclical on an eleven year cycle, and also stronger and weaker cycles on even broader cyclical scales. Currently, we are at a low point in the current cycle. Activity should rise over the next few years. I don't believe we have the power to effect changes in the Sun's flare output. We are just tiny in physical magnitude by comparison. The sun wouldn't even notice our largest nuclear explosions. However, if you could alter the shape of Earth magnetic field, using some kind of Tesla machine perhaps, you could, in theory, open a gap in the field to allow a targeted region to be fully exposed to an incoming solar flare. There are already gaps in the field all the time, due to how it works, and ions already enter along these gaps now. They have used HAARP to heat the ionosphere over large enough regions to alter the direction of the jet stream, and thus change the weather. So, in a similar approach, perhaps you could nudge the magnetic field just a little, for much dramatic results. Your idea is not as crazy as some may think.