The grid needs the supply and demand to be balanced for the power to be stable. Otherwise you get fluctuations in voltage and frequency which are both bad for anything connected to the grid.
There can absolutely be an oversupply of energy. We need to either find ways to store that surplus energy, or use it for something positive like desalination or carbon capture.
One of those tiny low power PCs with OpenSense is a good alternative, but a bit more work. The only downside is that you need a separate switch and wifi access point.