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The world’s largest solar companies have filled three floors of the Moscone Center in downtown San Francisco this week with solar gear, everything from next-generation solar panels to robots that assemble solar cells. But it’s the batteries, which can store the electricity produced by the solar panels, that have emerged as the real stars of this year’s Intersolar North America show.

Battery giants, eager startups, solar firms and European power players all showed off battery products that they hope to sell to homeowners, businesses and utilities in the U.S. These batteries can connect to solar panel systems and store energy during the day to be used later at night. Such battery systems can also be used for backup power in the event of a grid blackout, or also paired with an electric vehicle.

Part of the excitement around grid batteries this year has come from the huge bet that electric car maker Tesla Motors and partner solar installer SolarCity — led by the charismatic Elon Musk — are making on lithium ion batteries. Tesla is building a massive battery factory somewhere in the U.S. that will dwarf the world’s lithium ion battery supply, and the batteries will be used for both cars and paired with SolarCity’s solar panel systems.

But one entrepreneur’s attention doesn’t make a market. Energy storage has its own momentum. The entire energy storage market is predicted to explode over the next five years, due to a combination in the growth of solar, state mandates (like the one in California) that are pushing storage, and more unpredictable weather that can cause blackouts and require backup storage systems.

Research firm IHS predicts that the energy storage market (which includes batteries but also other storage technologies) will grow from a small base of 0.34 GW installed in 2013 to an annual installation size of 6 GW in 2017 and over 40 GW by 2022. The U.S. is supposed to be the largest market in the world, followed by Germany and Japan.

At a booth at Intersolar staffed by Korean electronics giant LG, curious attendees flocked around a battery that LG had quietly placed on a wall with just a few lines of basic information. “Are there any brochures for this?” numerous passersby asked the booth attendants, eager for any data on the device.

LG’s Joon Son, manager of the Solar Products Planning Team, told me that the LG energy storage system will go on sale in Europe in 2015, and if there’s demand, in the U.S. in 2016. The product contains a lithium iron phosphate battery that Son said LG procured from another company. LG said it hadn’t set the target price yet.

The battery weighs 121 lbs, and has a capacity of 2 kWh, but can be scaled up to 18 kWh (9 modules). The product can also be monitored remotely with a smartphone and can be plugged into any clean energy source, like solar panels.

LG was just one of dozens of companies showing off batteries that had been wrapped up with computing and turned into smart and sleek systems for solar panels and buildings. Many of these batteries were also being paired with inverters, which are devices that convert the direct current from the solar panel into alternating current that can be used around the house.

Most companies at the show were figuring out various ways to package up lithium ion batteries, which is the tried and true standard battery technology used in our laptops and cells phones, as well as Tesla’s cars. But the problem with lithium ion batteries is that they are still relatively expensive. Though, Musk’s and others’ position is that lithium ion batteries will continue to drop in price as they get built at a larger and larger scale.

German power company Varta Storage showed off a storage product made with lithium ion batteries and paired with an inverter called Engion. German company Sonnenbatterie showed off three types of storage products — with different functions and price points — made from lithium ion batteries. A 15-month old Valley startup called JuiceBox is selling a box of lithium ion batteries and a controller and they’re looking to team up with solar installers. Outback Power has been selling off-grid batteries for over a decade, but has focused mostly on lead acid batteries.

Startup Aquion Energy was one of the rare companies at the show that wasn’t betting on lithium ion. It has actually invented its own new form of battery made from basic materials like sodium and water (which are cheap and abundant). The battery tech was developed out of Carnegie Mellon University by founder and chief technology officer Jay Whitacre, and this year Aquion moved into early commercial production.

Different types of batteries will prove more popular with different customers and for different applications. Lithium ion batteries use high power and provide short, shallow bursts of energy, so that would make them a good fit for frequency regulation for the grid. But utility-scale clean power applications generally need several hours’ worth of sustained, low-power energy. Other battery chemistries like Aquion’s could end up being a better fit for that.

One thing is certain, if batteries end up filling up our cars, embedded in every one of our gadgets and in a big box in our homes, the world will need a lot more batteries. Which means all of the companies looking to sell storage products at Intersolar aren’t necessarily in strict competition with each other, they’ll entering a potentially massive and complicated new market.