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You'd need to size the generation for your worst days, not the average over the year; if you're using any kind of electric heating (e.g. reverse cycle air con),

You'd need to size the generation for your worst days, not the average over the year; if you're using any kind of electric heating (e.g. reverse cycle air con), and your generation is lower in the winter months, you'll drain your battery each day, and the overabundance in the summer months doesn't help you. Add in more solar panels for this, as well as the cost of a battery that can store a few days worth of power, and you're talking a substantially larger expense to cut the grid tie. However, the days of 100 year paybacks are clearly behind us if we're seriously doing back of the napkin math here. The progress in the field is impressive.

richardw 7y ago
It might be cheaper to add a generator for exceptional days. Build the rest of the system for efficiency.
mattlondon 7y ago
> your generation is lower in the winter months, you'll drain your battery each day, and the overabundance in the summer months doesn't help you. Certainly in the UK, you sell your over-generation back to the grid. This will offset the cost of buying from the grid on the days when your generation is lower than consumption. Certainly in the UK you may never get 100% net zero cost (not enough winter sunshine hours I suspect), but will help since most homes in the UK are heated via gas (as in gas, not petroleum)