Tesla’s grid battery ambitions hinge on three crucial factors by Kirsten Korosec @FortuneMagazine April 30, 2015, 11:02 AM EDT E-mail Tweet Facebook Linkedin Share icons If the trickle of Twitter teasers, the recent note to shareholders, and comments from CEO Elon Musk haven’t been enough to express Tesla Motors’ growing grid battery ambitions, than perhaps the $65 million in rebates slated for the company’s 2014 energy storage projects gets the message across. Tesla TSLA is no longer just a tech-inclined manufacturer of all-electric cars—a description many at the company don’t adhere to anyway. Is it a technology company that happens to make batteries and highly stylized electric cars? Or is it an “energy innovator” as Tesla’s co-founder and CTO JB Straubel envisions? Tonight we might find out. In a highly anticipated (and hyped) media event hosted by Tesla at their design studio in Hawthorne, Calif., Musk plans to fill in the details–or so we hope—on Tesla’s energy storage plans. Tesla’s interest in energy storage isn’t, and shouldn’t be, a surprise. As noted by Fortune this week, Tesla has been working on energy storage for five years now. And the company plans to produce 50 gigawatt hours per year of capacity of battery packs, compared to just 35 gigawatt hours of capacity for the individual cells that are housed in the packs, at its gigafactory in Reno, Nevada. The additional 15 gigawatt hours per year of battery pack capacity will be used to build stationary battery packs, Straubel told an audience at the 2014 Energy Storage Symposium last May. But even with all this activity, many details are unknown. Here’s what we’ll be paying attention to at tonight’s event in Hawthorne, Calif. Products Tesla’s residential energy storage product—which is bundled with SolarCity SCTY rooftop solar panels—is in more than 300 California homes. Its 400 kilowatt-hour commercial battery packs are installed at 11 Walmart stores, two BG’s Wholesale Club sites and throughout the Burton School District in California’s central valley, according to a SolarCity spokesperson. These installations, however, stem from an existing partnership with SolarCity. Tesla’s recent activity indicates a far more expansive vision that could involve numerous products. Will Tesla try to provide energy storage products for the residential, commercial and utility customer? If so, what will that breakdown look like? Or will it back away from homeowners and focus instead on businesses and utilities? Sam Jaffe, a longtime analyst, formerly of Navigant Research, and now CEO of startup Cyngus Energy Storage, is bullish on the utility market and also sees potential with commercial products. In Jaffe’s view, residential is the question mark. “There’s more risk than opportunity on the residential side,” Jaffe told Fortune. “It’s not clear if there’s an opportunity at all. So, if that’s the basket in which they’re putting their eggs, there’s a tremendous amount of market risk. In the end, homeowners don’t want to be electric utilities.” Partners If Tesla launches—as expected—a utility-scale energy storage product, the company will likely have partners. Who those partners are will give investors an indication of where Tesla is focusing its utility efforts. It will also demonstrate how well (or not) Tesla has spread out the cost and risk of launching a new product or business unit. Price Despite tremendous interest in energy storage, cost has prevented utilities from making large-scale purchases of batteries, Jaffe says. That’s about to change. The price of high-quality lithium-ion batteries will fall enough by 2017 or 2018 to trigger a buying spree by utilities, Jaffe says. The question is whether Tesla’s large-scale utility product will be cheap enough. Jaffe believes the pricing sweet spot is between $500 and $1,000 per kilowatt-hour for an entire lithium-ion utility-scale energy storage system, including the power electronics, software, and battery management and communications systems. Pricing on smaller residential systems will need to breach the $1,000 per kWh barrier as well before it will begin to make sense in an unsubsidized market, Jaffe says. “And that’s really hard to do with such small systems because of the higher cost of the inverter and other balance-of-system parts, as well as the fact that there are fewer kilowatt hours to spread that across,” Jaffe says. Tonight will tell whether Tesla’s plans have spark, or if they’ll need a recharge before taking off.