Someday we could all have a home battery

Amidst the grid-climbing robots, smart thermostats, and electric cars at the smart grid conference DistribuTECH in San Antonio, Texas this week, battery makers were touting their low-cost batteries as energy storage for the grid, for buildings, and some day, homes. It’s not so unfeasible that in the future many homes could have their very own battery, likely to be combined with a rooftop solar panel.
In Panasonic’s booth — the company bought controlling interest in Sanyo back in 2009  — a battery box was featured. The box strings together hundreds of small format lithium-ion laptop batteries in much the way Tesla (s tsla) for its electric car battery. (Note: Tesla also uses Panasonic laptop batteries.) A couple of battery stacks would be enough for a single family home, combined with an inverter already retailing in Germany (one of the largest rooftop solar markets) for less than $5,000. A few years ago there were reports this battery could store a week’s worth of electricity.
A startup from Costa Rica, Heart Transverter, was showing off a box that can combine inverters and batteries and connect with distributed power generation like a fuel cell or solar system. The idea is to put one of these in your basement or backyard and you’re set to plug in all your off grid power needs. An on-looker in front of Heart’s booth called the transverter the most sophisticated inverter and energy storage system out there.
Panasonic might have a residential home battery product for market, but it’s is mostly targeting larger commercial building operators and utilities (see the photo the left), and the battery maker is already supplying batteries for some utility pilot programs in the U.S. Lithium-ion batteries are starting to be more regularly explored by utilities and power producers and both AES (s AES) and China State Grid have built massive battery farms using batteries from A123 Systems (s AONE) and BYD, respectively.
Then there’s home energy storage potential of electric cars. EVs could be used as grid regulation through a two-way connection with the utility known as V2G, and older EV batteries could also find a second home as a battery after it’s no longer useful for the car (see Nissan’s project with its LEAF).
While the batteries I’ve mentioned so far are pretty expensive right now, and will likely be sold in the developed world, the developing world is more rapidly adopting much smaller (and less advanced and expensive) batteries connected with tiny solar panels. Fenix International makes a lead acid battery box with connectors for charging cell phones and distributed clean power.