It would be a good balancing factor that the ring requires a constant upkeep of whatever megawatt value to remain charged, if your grid goes in the negative, the ring should also lose charge until it can't teleport anymore. As it is now, you don't actually need a strong powergrid, you just need to wait for the ring to charge.
Could make it inversly proportional with quality too, higher quality makes rings charge faster and discharge slower.
Afaik the ring is already coded as a giant accumulator so the mechanics for this are already in place.