Tesla began producing its next-generation Megapack 3 grid battery at its facility in Brookshire, Texas, on August 6, a step that could help utilities bring large-scale energy storage online more quickly. Compared with the earlier version, Megapack 3 stores about 28% more energy without taking up any extra space, which could help grid operators add resilience without finding larger sites. What's happening? On August 6, Tesla said Megapack 3 produ…