What might be the cheapest way to install a Tesla Powerwall + solar?

Note: The Tesla Powerwall 1 was released after this post and required a separate Battery Inverter and the existing solar inverter. The Powerwall 1 has since been superseded by the Powerwall 2, which has an integrated Battery Inverter – and AC couples to a solar inverter.

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[Note: This blog post is an educated guess on how the Tesla Powerwall might work based on stuff Elon Musk has publicly said and the press section of their website. So bear that in mind if making any decisions based on this post. Tesla have released sketchy and often contradictory technical details about the Powerwall, so it is impossible to be sure how the thing will work or integrate into an existing system. I’ve tried asking Tesla US and Tesla Australia for clarification, but with no luck.]

Since Tesla announced their low cost home battery, many solar installers have been looking for the cheapest way to integrate one into your home’s electrical system.

This has led to the emergence of a whole new category of residential solar system, that had never really been considered here in Australia before the Tesla announcement – the not-very-catchy “Hybrid Solar Without Backup” system.

This is a system which, to save thousands of dollars on the install, removes the ability for the batteries to power your home if the grid goes down. The batteries are only used to store solar energy. They cannot be used in an outage. [Read more…]