To put the costs intro perspective, an 83 Amp Hour car battery (typically a small car might have a 40-60 AH battery and a large car >100 AH) holds 1 kWh (kilo w

To put the costs intro perspective, an 83 Amp Hour car battery (typically a small car might have a 40-60 AH battery and a large car >100 AH) holds 1 kWh (kilo watt hour). An 80AH battery can be had for about $100 on eBay. The article states that the cost of materials might be $100/kWh. So you could get the storage for about the same price using a car battery.