Tesla CEO Elon Musk not-so-quietly unveiled a new product, the Powerwall Tesla Home Battery, last week, that stands to change the way everyone thinks about solar power and sustainable energy. Until now, putting photovoltaic panels on your roof was a nice, if expensive, thing to do to help off-set your energy costs, but hardly posed a viable solution to our country's dependence on fossil fuels. Now, with batteries produced at Tesla's Gigafactory that can store up to 10 kilowatt-hours of power, the energy your solar panels absorb can actually be banked in a practical way to power your home all night long. And as Popular Science reports, Tesla's Powerwalls are very affordable compared to other similar products on the market — $3,000 to $3,500, vs. $30,000 for Bosch's solar battery solution.

Both models, the 7 kWh and 10 kWh versions, weigh in at 220 pounds and are four feet long and almost three feet wide, but merely 7 inches thick. They're expected to start shipping this summer. For reference, it only takes 0.1 kWh per day to light a room, and 1 kWh can charge your cell phone 278 times over.

"The issue with existing batteries is that they suck," said Musk at the unveiling on Friday. He says we should be using our "handy fusion reactor in the sky called the sun" in order "to change the entire energy infrastructure of the world to zero carbon."

As Vice surmises, Musk is sure to piss off major power companies like PG&E as his product takes off, because until now customers who have already installed solar arrays have had no real way to off-set their energy bills with the excess power their solar panels produce, or to store that power for their own use. The Powerwall now makes it possible to disconnect completely from the power grid, and to power your own home during outages.

Here in California there are rebates available and tax credits that make installing solar panels even more affordable. And given that the price of one of these Powerwall batteries is equivalent two just two years (or less) of electrical bills for a lot of people, this could be a game-changer.

Below, Musk's tweet teasing the battery, and connecting it to his sustainable car business.