Retrofitted a battery to the house. Have 20 solar panels, 5kW system. We drive an EV that is powered by the solar-fed house battery. Around $2,000 a year saved on petrol costs. Battery bought in June 2018; it has saved $4,557 in electricity costs to date. Over the 4 years since the battery was bought, on average the house is self powered 61% the breakdown being: 34% solar, 27% powerwall (battery) and 39% from the grid.
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