Energy storage technology is a hot topic in the clean energy community. Companies like Tesla Motors and Daimlyer are all now producing home energy storage units that you can purchase and install to compliment your home solar power system ( assuming that you have a home solar power system installed already).
Researcher the world over are working to find an economical solution to this grid level energy storage problem. Solving it is very much in the best interests of the electric utilities since if we cannot solve it consumers may choose to simply add energy stoarge and solar to their homes and businesses.
The price for solar pv and home energy storage is continuing to fall and as huge giga factories are brought online the price of manufacturing both will drop even more. At some point soon solar pv will come down to 3 cents and kilowatt and solar + storage may be as low as 5 cents!
University Level Lecture For The State Of The Art For Energy Storage Technology.
Here is a great university level lecture outlining the opportunites to be realized from economical energy storage technology and the different ways researchers are working to solve it.