going forward, solar pv and batteries will continue to get cheaper, but each house will vary quite considerably in how to maximise and optimise things for what will always be an exercise in averages that is modified by whatever contingencies are included, and after living off grid for decades I could care less and recomend careing less about the math, start now with something modest, iterate,learn, end then install the largest system that you can. If you are going to build new, start with site selection, plan for car charging, and use all of the best practices for integrating passive solar into the homes structure.ie : homes built with double walls and a thermal break require NO home heat source as normal domestc activities will generate excess heat that must be vented. Anywhere north or south of 30° design should be for bad weather in the winter, and the rest of the year will almost certainly be gravy. For all refits and renovations to solar, the math will always be ,the most that will physicaly fit. Regulatory limitations will most certainly restrict batteries to a day or two backup in most situations.In most jurisdictions, a large battery would require a seperate building with significant set backs to any structure, untill we get to solid state non flamable batteries, which may be on the horison now.