It's official: Tesla is building batteries - and Wal-Mart is already using them

Next week, Tesla is preparing to unveil a new line of electric batteries for use in the home and by businesses, Bloomberg reports - and they are apparently already being used in Wal-Mart stores.

Tesla's move in batteries has been long-expected. CEO Elon Musk hinted at the company's intentions to build batteries back in February, and in March he tweeted that a "major new Tesla product line - not a car" is to be unveiled on April 30.

In an email to analysts and investors, also seen by BuzzFeed News, head of investor relations Jeffrey Evanson has now confirmed that Tesla plans to introduce the "Tesla home battery and a very large utility scale battery."

Evanson adds: "We will explain the advantages of our solutions and why past battery options are not compelling."

Bloomberg has more detail on Tesla's intentions, revealing that the company is already actively testing out the batteries in a pilot program in California. Some 300 homes have been fitted with the home batteries, along with 11 Wal-Mart stores. Cargill is another company planning to use the batteries.

Other commercial plans include "powering its factories ... [and] reducing electric bills at schools and wineries."