Elon Musk strode confidently into the future when he started Powerwall production at Gigafactory in October 2016. This signaled the end of household solar batteries in discreet corners. Now we have something elegant to decorate our walls with pride.
The Birth of the First Powerwall
Tesla’s first power wall arrived on April 30, 2015. This offered a choice of seven and ten kilowatt-hour capacity. In addition it had a DC-to-DC interface with solar panels. Within a month, production sold out to mid-2016.
Powerwall uses a daily-cycling, nickel-manganese-cobalt battery. This has 92% round trip efficiency. Thus, it only consumes 8% of the energy it stores.
This exceeds the overall grid-storage target of 80%. The second generation Powerwall uses similar technology. In addition, it incorporates a DC-to-AC converter for interface with home grids.
Powerwall’s Big Brother PowerPack
Tesla makes its powerwalls for home use. Hence they store electricity for solar self-consumption, time-of-use load shifting, backup power, and off-grid applications. They can have 5,000 recycles before the warranty expires. The company has developed a larger 200 kilowatt-hour PowerPack for commercial and utility grid applications in parallel.
Tesla sold 100 PowerPacks, and 2,500 Powerwalls in Africa, Asia, Europe, and North America in the first quarter of 2016. The two products were soon delivering a combined 300 megawatts of hour globally. By comparison that is a third of the output of a single unit, medium-size nuclear power station.
Is Powerwall ‘Another Toy for Rich Green People’
Powerwalls retail at around $6,500 in the U.S. including installation. Third World currencies put the nickel-manganese-cobalt technology beyond the reach of underprivileged people. Furthermore, utility prices need to be high to cost-justify it. Strictly speaking, the numbers only add-up on remote islands where generator fuel arrives by ship or plane. However if we factor in a carbon tax the sums might work the other way for Powerwall.
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