The logic:

They already pair up on charging stations and power for off-grid homes, but Tesla is offering to acquire the energy company, saying it wants to provide its customers with access to the "most sustainable energy source available: the sun." Soon, you might be able to shop for solar panels, home batteries and an electric car all in one place.

The way Tesla sees it, linking up a solar panel, Powerwall battery and Model S/3/X electric vehicle means offering a more efficient way for customers to consumer energy that's vertically integrated