Its more than an interesting idea, there is a couple of electricity retailers down south have variable tariffs and consumer programmable software that allows you to set parameters to trade electricity according to its spot price, the level of charge in your batteries and the time of day. For example its late morning, your batteries are fully charged so you would be willing to sell at less than the standard retail price because any more generated by the panels will be wasted. Conversely if its early evening and your batteries are only 50% charged but the retail price has suddenly spiked to double the normal rate because of high demand. You could sell some more power because the price will most likely drop again later allowing you to use the grid supply at a more reasonable rate.The major difference between a fixed battery and a mobile one is that the car would always need to have a minimum level of charge available for use and if its main purpose was the daily commute then it would have to have the required amount of charge + a safety factor at the specified time each morning. Since the longest life is obtained from a Lithium battery when stored at a medium level of charge and avoiding high charge/discharge rates all these factors and others can be programmed in. The retailer also has the ability to override the software to utilise yourbattery for network stability purposes.
