Could a solar storm wipe out bank records?

Probably not. A solar storm is very unlikely to permanently wipe out bank records.

What a severe solar storm could do is disrupt power grids, satellites, communications, and internet service, which can make banking systems hard to access for a while. The main risk is temporary outage, not permanent loss of records.

What is more likely

• Online banking and card networks could go down temporarily.
• ATMs and payment terminals could stop working if power or communications fail.
• Banks might need time to restore full operations.

What is less likely

• A solar storm directly erasing bank databases is not the typical outcome.
• Bank records are usually protected by backups and other recovery measures, so even if systems are disrupted, the data is generally expected to survive.

Important caveat

In a very extreme event, repairs to the power grid and communications infrastructure could take days, weeks, or longer, so access to your money could be delayed even if the records still exist.

So the short answer is: a solar storm is much more likely to interrupt access to bank records than to destroy them.