Atypical magnetic solar storm

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I've heard that there could occasionally be unusually powerfull magnetic storms(solar flares?) caused by the sun, a magnitude that has not yet occured since electricity has been used, but a burst which could knock out all power generation equipment on earth(or a large surface of earth). Knock out, not as in that causes a black out (like has occured in the 90s) , but as in destroy electrical generation equipment (black out for months until equipment is rebuilt and redeployed in powerplants). Does anyone here know about that?