[Editor's note: The $10,000 price quoted by Sungevity-Sonnenbatterie applies to the battery system only, not the storage+PV package, as we had previously reported. Last night, Tesla announced that its battery would sell for $3,500 -- not the $13,000 initially reported. Elon Musk said "there's nothing remotely at these price points."]

Sungevity and Sonnenbatterie may have upstaged Tesla's coming energy storage news by announcing a cheaper product.

The largest private residential solar installer in the U.S. and the leading home battery system supplier in Europe unveiled a partnership yesterday as financial markets were in a frenzy over a planned residential energy storage launch from Tesla Motors, which is working with SolarCity.

John Ordoña, Sungevity’s vice president of communications, told GTM that pricing for the fully integrated battery system “is still to be finalized, but we expect it to start below $10,000.”

If so, that is a reduction from the $13,000 system that Tesla’s CEO Elon Musk is expected to unveil later today. 

Sungevity’s customers in the U.S. and Europe will be able to buy Sonnenbatterie smart energy storage systems in the second half of this year, at which point the solar company will reveal further details on pricing and business models.

Ordoña confirmed the battery system will not need to be installed separately from the solar panels. “The Sonnenbatterie comes as an integrated system with a beautiful form factor,” he said. “All elements of the energy storage system are fully integrated.

“The system is then combined with panels, solar inverters, and other components into one Sungevity Energy System that’s installed at the customer’s home or business. The purchase will be as easy and straightforward as it is to purchase one of our solar systems today.”

It is unclear at this stage whether the alliance marks a push by either partner to strengthen its position in the other’s primary market.

Sonnenbatterie, which uses Sony's Fortelion lithium-ion cells in its residential products and secured $10 million in funding last December, is mostly focused on the European market, with operations in Germany, Austria, Switzerland, Italy and Spain.

It opened an office in Los Angeles just over a year ago, but the bulk of its 8,000 smart energy storage unit sales to date are believed to have been in Europe, where it is also readying for expansion into the U.K.

Meanwhile Oakland, Calif.-based Sungevity has a strong focus on the U.S. market, serving Arizona, California, Colorado, Connecticut, Delaware, the District of Columbia, Maryland, Massachusetts, New Mexico, New Jersey, New York, North Carolina and Vermont.

In June of last year, Sungevity announced a partnership with E.ON Benelux to offer its products to customers in the Netherlands on a co-branded basis. At the time, Sungevity executives said it was the start of a campaign to expand throughout Europe.

Further European market entries have yet to be announced, however. For now, said Ordoña, the companies see the partnership as a mutually beneficial one.

“We are both leaders in our respective sectors in Europe and the U.S., the two markets in which we will initially launch our combined product offering. Sonnenbatterie holds the leading share in Europe and Sungevity is the largest privately held solar company in the U.S.," said Ordoña.

A focus on Europe would give Sungevity another edge over SolarCity, which is limited to the U.S. market.

Tesla, meanwhile, has a growing presence in Western Europe. But it is not clear how the company will build on its distribution network to deliver energy storage to European markets.

Will this mean more similar alliances for companies looking to expand in Europe? As GTM reported previously, battery system providers working on their own in Germany are having a tough time, and local and foreign manufacturers alike are jostling for leadership.   

The strongest players in the solar and energy storage sectors are looking to consolidate their positions before it's too late.