With the Powerwall, Tesla brings the fuzzy, sci-fi concept of home energy storage into sharp focus.
Elon Musk is undaunted by the planet’s most complex challenges. To combat rising atmospheric carbon levels, which are meaningfully changing the chemistry of both the atmosphere and oceans, the Tesla chief executive has devised a two-part solution. Part One already exists: the sun. “We have this handy fusion reactor in the sky,” he told a group of Tesla fans at a May 2015 event. “You don’t have to do anything. [The sun] just works. It shows up every day and produces ridiculous amounts of power.” Tesla’s bold stroke is the introduction of Part Two: batteries.
Not just any batteries. Safe, functional, even sexy batteries produced at a scale that makes them affordable. Tesla’s advanced lithium-ion batteries already power the company’s popular electric cars. Now the company is tackling the biggest issue handicapping the broader shift to renewable power—intermittency. The sun doesn’t shine at night, and the wind doesn’t always blow. Stored solar and wind power bridges the intermittency gap.
Enter the Powerwall
The Powerwall is Tesla’s rechargeable lithium-ion home battery. Designed to hang unobtrusively on a wall, the 7-inch-thick power pack stores home-generated wind or solar energy or energy from the grid. In certain locales, it saves homeowners money by allowing them to shift energy consumption to off-peak pricing periods. And as a backup power source, the Powerwall provides peace of mind. Musk and Tesla’s chief technology officer, J.B. Straubel, designed the home battery for ease of use and performance: a liquid cooling systems keeps it safe; software seamlessly integrates with solar inverters and external grids; the svelte shape and aluminum casing material even give it a sculptural beauty.
- Solar Panels Rooftop photovoltaic panels convert sunlight into electricity to power your home during the day and charge the Powerwall for use at night.
- Powerwall Installs easily on a wall in your utility closet, garage or other room. Can be charged with electricity generated by solar panels or from the utility grid.
- Inverter Converts electricity between direct current, known as DC, generated by solar panels and stored in the Powerwall and the alternating current, known as AC, needed to power most household appliances and lights. If you don’t have solar panels and are using your Powerwall as a backup power source, the process is reversed: The inverter converts AC from the utility grid into DC to charge your battery.
- Electrical Panel The inverter sends AC to your home’s electrical panel. Or, for backup applications, it sends DC to the battery from the grid.
- Backup Panel and Switch For backup applications, you may install a secondary circuit box that powers only critical appliances. If you also have solar panels, you can install a switch that automatically powers your secondary circuit using solar and battery power.
Most homes use more energy mornings and evenings rather than midday, when sunshine is most plentiful. Without a home battery, home solar producers typically sell excess electricity to the utility and buy it back when the sun goes down. The Powerwall bridges the supply-and-demand gap, letting homeowners use more of the solar energy they produce when they need it.
Load shifting Saves homeowners money In communities where off-peak pricing discounts exist, the battery can provide ﬁnancial savings to its owner by charging during low-rate periods and discharging during more expensive rate periods.
Bridges generation gaps Lets wind and solar work day and night The battery can store surplus solar energy for use later, when the sun is not shining.
Back-up power Keeps your house running during outages Powerwall stores enough juice from the grid to power a refrigerator and lights for four days. Combine it with solar panels, and you can power your entire home throughout an outage.
Renewable Energy Tipping Point
Renewable energy production has been slowly gaining ground from fossil fuels. For Musk, the ability to store wind- and solar-generated energy will finally give renewables the edge.
Of all the fossil fuel consumed in the U.S., one third goes towards transportation and another third towards electricity production. With its popular electric cars, Tesla is already chipping away at the transportation slice of the pie. The Powerwall and its commercial counterpart, the Powerpack, address electricity production.
Every year, the electric power sector produces 2 billion metric tons of carbon dioxide, the equivalent of burning 225 billion gallons of gasoline. According to Tesla’s calculations, renewable energy coupled with battery storage—in cars, homes, businesses and utility companies—will allow the U.S. to retire the top 50 percent of the dirtiest power generation sources.
Plenty of Solar Energy
By Tesla’s calculations, solar panels covering less than 4,000 square miles (about the combined area of Travis, Williamson, Bastrop, Caldwell and Hays counties) would generate enough energy to power the entire United States. The beauty of solar power, when spread across U.S. rooftops, is that it doesn’t require disturbing farmland, forests and other undeveloped land.
To make its global-scale vision for battery storage a reality, Tesla designed a next-generation manufacturing facility. Gigafactory 1, as the Nevada facility is known, is “not really a factory in traditional terms—a building with a bunch of off-the-shelf equipment,” Musk explained at the Powerwall launch. “What we’re really designing is a giant machine. [The Gigafactory] is like a product of Tesla. We’re making this really big product that doesn’t happen to move.”
The idea is to replicate the Gigafactory over and over in different parts of the world. Musk admits this isn’t something Tesla can do alone. Many other companies must build Gigafactory-class battery plants. To that end, all of Tesla’s patents are open-source and available to anyone for free. “We want to show people most importantly that this is possible,” Musk said.