The solar contributed 55% of the household power, during daylight hours, and the battery contributed 44%, during the evenings. Obviously the battery supply was created by the solar panels during the day. Can you see how much the house consumed directly from the grid? The little black line at the top is their consumption of grid electricity, which is 1%!! So 99% of the Wood’s household power was self-generated in this period. The solar panels were also feeding into the grid throughout this. However I should note that this doesn’t include any winter months, so it will be interesting to see what the data comes up in the winter.
Although the battery cost them $12,000 and the solar was another $3000, they have saved $779 since December last year, not including the first lot of solar which was already paid off by the time they installed their second system and battery. Their payback period will be 10 years. Rob and Larraine are moving into a new house in an over 55’s estate shortly, and they’re taking their tesla battery with them. Since December last year, the Wood’s have saved 5.22 tonnes of greenhouse gas (that’s about the equivalent of 6.1 acres of forest over a year, or not driving your car for a year). Financially, that’s come to $1576.