Spanish Electrical Grid Instability

Since being in Spain (3yrs) I’ve had two motherboards go bad. Not completely bad, but throwing errors, freezing, etc. I’ve never had this problem before so I plugged in a Shelly switch with power monitoring, connected Homeassistant and monitored it for a few weeks. In a 7 day period the voltage ranged from 213VAC to 240VAC. This is an insane voltage sweep. I can see 20VAC variance in 24hrs or even sometimes 10-15VAC variation in one hour.

The frequency stays quite solid between 49.9-50hz with one 49.8hz dip in 7 days. So what this is telling me is that there are grid-tie solar installations near me that are flooding or reducing the measured voltage. This is concerning because either the grid operator cannot respond fast enough to the fluctionations or doesn’t really monitor voltage or their SLA is within 210-240 and that’s good enough.

I’ve since added an Automated Voltage Regulator before my sensitive electronics. Now the variation is within +-3VAC, well within spec. In the US I never had more than 3VAC fluctuation at any given time and the average change was less than 1VAC.