One of the main benefits of having a battery is backup power during outages. You can’t do that safely without adding a breaker between the utility and the hous

One of the main benefits of having a battery is backup power during outages. You can’t do that safely without adding a breaker between the utility and the house (to avoid backfeeding and killing linemen). In California, touching a breaker box is at least $10,000, so to amortize the cost of the paperwork, you need to put in a multi kw system. On top of that, you need to anchor it to the ground somehow, so that it doesn’t fly around in 50-100mph winds (which will happen about once during the lifetime of the panels). Portable systems exist, of course. You could get one of those. Also, a multi-kw system isn’t physically that big.