History of auroras and sunspot activity
Having started with modest and frequent examples of solar X-rays and coronal emissions, I will rethink the outcomes that would impact modern society from a more major event. On the positive side, they will give far brighter and spectacular aurora illuminations: in 1859 there was a major solar storm with the aurora seen as far south as Cuba (it is called the Carrington event, because he reported it). In 1859 we had the technology to have long-distance Morse code electrical communication along wires. Long lengths of electrical cable make excellent antenna systems for radio receivers, and were (and are) standard equipment when broadcasting at long wavelengths. The 1859 Morse code telegraph cables were responsive to the solar flare currents formed in the atmosphere. They sucked energy from the atmospheric electrical-magnetic storm and sent pulses of high voltage along the cables. There were reports of sparks and shocks to the telegraph operators and surges in power that were greater than provided by the power units. The electrical storm was serious, even for such primitive electrical systems, as telegraph lines and equipment were made non-functional or destroyed.
By 1921 electrical generators and equipment had become major features of industrial nations. Power units were often linked directly to the equipment they were running, rather than being interlinked into any national power grid. This was fortunate, because there was a modest sunspot event that intersected our orbit and caused problems in the northern hemisphere. As in 1859, the telegraph operators reported high voltages, damaged equipment, and flames coming from the cabling; in both the USA and Sweden, telegraph control buildings were burnt down by the electrically generated fires. In New York, the Central Railroad signalling equipment was destroyed and a fire took out at least one building. Overall, the events were isolated because the power and signal lines that acted as antennae to bring excess power into the systems were relatively short and independent.