Nissan has this week announced that it has partnered with an American company to manufacture and market energy storage solutions. These are lithium ion batteries made at its UK plant. It will also use if the customer wants it second hand car batteries in the units.
The units will be about the size of a conventional boiler. Its difficult to say how much they will cost but reading between the lines I would say the initial cost is about £5000 including installation. The question is at this cost can such energy storage solutions pay for themselves in the lifetime of the system*. I think its doubtful. Looking at my numbers for my exported electricity the avoided cost saving is about 11p/unit and I will export about 1MWh this year. You do the math. The companies reckon the saving is much higher £43/month. How they get this figure and what size systems its calculated on I have no idea. Almost certainly the larger the systems the more export the better the economics. However, with large systems you are more likely to fell your batteries then start sending electricity to the grid with just one such unit. Buying two or more units puts the economics back to square one. One way the economics can be improved is that such systems encourage the use of “time of day deals”. I don’t know. I think its a great idea I’m sure I will have one – but the costs will have to fall first.
* lifetime of batteries the rest of the system will last longer so replacing the batteries only (which will be cheaper and cheaper) will improve the economics once you have been through one cycle of batteries (10 years). Once the system has paid for itself it will also make PV payback quicker.