Even if you can charge for free the batteries only have a limited number of charge cycles so you have to pay for the wear and tear on the batteries. Last I hear

Even if you can charge for free the batteries only have a limited number of charge cycles so you have to pay for the wear and tear on the batteries. Last I heard the economics were pretty close to neutral for the US: From http://www.catalyticengineering.com/top-ten-facts-about-teslas-350kwh-powerwall-battery/ http://www.catalyticengineering.com/top-ten-facts-about-tesl... "So revenue is $1.66 x 183 days x 10 years = $3,000. You’ll just about recoup the cost of the product, but you won’t profit because of two factors – the cost of inverter and installation, and the time value of money. We’re in a low-interest environment, but setting aside $7,000 today to make back $3,000 over 10 years still leaves you down $4,000 – not a very good deal."