It's actually Panasonic solar panel + SolarEdge inverter, that Tesla puts their sticker on. Tesla is just an installer of third party products, like majority of all other solar companies. That can possibly change with solar roof, but it's very early stage.
In the new context a large solar installation connected to the grid is more cost effective if you need a grid for nighttime. The real question is whether batteries will make it so you don't need that. They're currently too expensive for that, but they're also declining in price. So if batteries get cheap enough that you can run your home from local panels and batteries without needing the grid, the cost of needing to keep the grid when you could otherwise not have it anymore makes the centralization lose its cost advantage.
Moreover energy produced by solar panels in homes is locally consumed, therefore there is no maintenance (nor any non-neglectable cost or loss) related to distribution (they are non neglectable).
