The answer to 'how does panel upgrade work' is that a panel upgrade is the process of replacing an older, outdated electrical service panel with a new, larger capacity panel. This is typically done to increase the amount of electrical power available to a home, accommodate new high-powered appliances, or bring the electrical system up to current safety standards.
The process usually involves an electrical contractor assessing the home's current electrical needs, obtaining the necessary permits, disconnecting the old panel, installing the new panel, and connecting the new panel to the home's electrical system. This may also include upgrading the main service line from the utility company. A panel upgrade can take 4-8 hours and requires a professional electrician to ensure it is done safely and up to code.