Tesla just announced that its Gigafactory is now in mass production mode, fabricating its own "2070 cells" to be used in the Powerwall 2, Powerpack 2, and Tesla Model 3 electric vehicle. By 2018, the company expects to manufacture 35 GWh of batteries every year. That increases the world's battery manufacturing capacity by almost a factor of two.

Just how much energy storage is that?

35 GWh Is Enough For…

Tesla makes batteries for the home and commercial energy market, as well as the electric vehicle industry. These batteries can provide storage to supplement renewable energy systems and they can be used for "peak shaving" to reduce electricity costs due to time-of-day pricing and demand rates.

For residential applications, the Powerwall 2 provides 14 kWh of usable storage. I call it "usable" storage because that figure takes into account the inefficiencies of converting AC to DC and back, as well as the additional capacity to ensure that the batteries aren't discharged too deeply. Tesla says that the Powerwall 2 has a 90% round-trip efficiency, and I'm assuming that they limit the depth of discharge to 80%. (80% depth of discharge means that you can drain 80% of its capacity, leaving 20% in reserve. This helps to prolong the life of the battery.) Factoring in both of those figures, I estimate that the Powerwall 2 actually has about 19 kWh worth of batteries. If the Gigafactory were producing batteries just for the Powerwall 2, then it could provide enough batteries to outfit 1.84 million Powerwalls every year.

Performing a similar calculation for the Powerpack 2, Tesla's 210 kWh commercial and utility-scale storage device, we can compute the actual battery capacity at 290 kWh. With that number in mind, the Gigafactory could deliver enough batteries for up to 120,000 Powerpacks annually.

The figures for the Model 3, Tesla's electric vehicle for the middle class, are a little sketchy. The company hasn't specified the size of the battery bank but claims that the car will have a range of 215 miles (346 km). Based on the other Tesla models, it's safe to assume that the Model 3 will have a battery bank of around 60 kWh. Again, taking into account efficiency and depth of discharge, that could be closer to 80 kWh worth of batteries. Every time the Earth goes around the Sun, the Gigafactory could produce enough batteries for more than 400,000 Tesla Model 3s.

Of course, the plant is making batteries for all three products, so the totals will be some combination of the above figures.

Powering the Gigafactory Itself

When Tesla first announced that the Gigafactory would be a net-zero energy facility, I ran the numbers to see if that's even feasible. Remember that net-zero energy doesn't necessarily mean off-grid - it just means that over the course of a year, the facility generates at least as much power as it uses. But just for the fun of it, I wondered how much battery capacity would be needed to make it an off-grid factory, powered only by renewables and storage. (Yeah, I do this stuff for fun. I'm a geek.)

I estimated that the Gigafactory would consume 2400 MWh (2.4 GWh) of electricity per day. In theory, then, in one year the Gigafactory could produce enough battery capacity to power the plant for about 14 days. But it would only need to store a few days' worth of energy, since Reno probably won't have two consecutive weeks of calm, cloudy days. Suppose it needs four days of autonomy - about 10 GWh. One year of Gigafactory production could deliver enough storage to power three Gigafactories. (Realistically they're not going off-grid anytime soon, if ever. I just had an envelope with some calculation space on the back, so I cranked out the numbers.)

The Process Is as Important as the Product

Tesla CEO Elon Musk told reporters that improving the manufacturing process is just as important as improving the product itself. He hopes that the state-of-the-art facility will allow Tesla to produce batteries for about $100/kWh by the year 2020. That's about half the cost of their batteries today. They'll need to get the price down if they expect to make a profit from the Model 3, which is expected to retail at $35k.

The 2170 battery cell - named for its 21mm x 70mm dimensions - is a departure from Tesla's older 18650 (18mm x 65mm) cell. According to Musk, the new dimensions were selected as a balance between physics and economics. Musk says that the new batteries are the least expensive and highest performing Li-ion batteries on the market, although he offers no evidence to support that claim. Tesla is not releasing information about the 2170 cell capacity. Nonetheless, the auto maker expects it to become the new industry standard for EV batteries.

Here's the Gigafactory production line in action:

Video courtesy of Tesla Energy

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