Energy storage is the currently missing link that will enable the intermittent renewable energy sources like wind and solar to play a much greater part in the future grid mix.
Now that more homes and businesses are installing photovoltaic systems, a new trend for combining these with battery backup is emerging.
Previously, battery storage systems were only thought necessary with solar PV and wind in stand-alone systems, separate from any grid connection, but as the grid supports more and more PV and wind systems, which can supply power only at certain times, the need for storage backup is becoming more apparent.
For large commercial installations this is especially attractive because, although they may have negotiated contracts with utilities that bring down their overall electricity rates, the fees that they are charged for the times when they do draw power, which can be based on their highest peak energy use during a month, have been rising as much as 10-12% per year.
According to Marcus Elsässer and other executives attending the Intersolar North America 2013 trade show held over the last three days, large commercial electricity users can reduce their peak demand and lower their demand charges by installing a storage system alongside a PV system.
Last month California set a proposed 2020 procurement target of 1.3GW of battery storage for network operators.
In Germany, grants from a scheme with a total value of €25 million are being offered to offer storage to existing solar installations.
Last month's Intersolar Europe trade show consequently saw over 200 exhibitors, including major brands, presenting their storage and smart grid solutions.
There, energy storage systems had their own dedicated section for the first time in any global energy trade fair. This particular show, the largest in the world for the solar industry, was attended by over 50,000 visitors from 47 different countries.
Energy storage plus PV was a key topic, with reference to many different types of storage, not just batteries, including flywheels, capacitors, heat storage and compressed air.
The German support scheme is managed by the state KfW Group bank, which provides a 600€/KW grant for new PV systems and 660€/KW grant for older systems. To receive support, systems must be in Germany, have a duration of at least five years, and no more than 60% of the installed power can be fed to the grid.
According to ">Ash Sharma of IMS Research, by 2017 the storage market is projected to be worth $19 billion, mainly due to the German scheme being taken up by residential system owners and operators of small systems up to 10 kWp.
As a whole, photovoltaic storage installations will, on average, he says, grow by over 100% for the next five years, up to nearly 7GW, rising to 40GW of battery systems by 2033.
Will this catch on here? The UK Department of Energy and Climate Change (DECC) is currently reviewing energy storage demonstrator proposals entered into a £17 million procurement competition.
There is a wide variety of entrants including some seemingly bizarre technologies: hybrid batteries to grid, smart energy storage, a radical proposal for using surplus energy to lift heavy aggregates that would be allowed to descend and generate energy at times of peak demand, flywheels, the use of electric vehicles for storage, liquid air, the conversion of surplus electricity into methane, cryogenic liquid nitrogen energy storage, and industrial scale lithium ion batteries.
A further potential winner under this scheme is Moixa Technology, an EU pioneer of smart direct current (DC) technologies, which has submitted a bid to install Maslow storage technology across 750 homes.
It works by shifting DC (direct current) loads from lighting, communications and electronic devices, to batteries during low tariff times, charged using local renewable sources such as solar PV, or at times of excess, wind power.
Simon Daniel, the CEO of Moixa, commented on the need for storage: “Just this week, the volatility of solar and wind resources created negative electricity prices and renewable curtailment in parts of Europe".
He says British distribution network operators face similar issues, especially at times of high sunshine, as now, or high winds. Daniel says that without using energy storage "considerable infrastructure upgrade costs, to reduce voltage issues caused by rising solar PV adoption" could result "which could otherwise lead to local blackouts or lost renewable revenue”.
He continued: “We’ve estimated that by using Maslow distributed energy storage systems with local solar PV, excess wind supply and low overnight energy prices, energy bills could be reduced by up to 30%, and keep essential consumer devices online if the grid fails”.
According to Anthony Price, director of the Electricity Storage Network, Britain should aim for an energy storage target of 2020MW (2.02GW) by 2020.
Speaking at the recent energy storage conference organised by the Institution of Mechanical Engineers, he said: “Meeting Britain’s power requirements requires energy storage as well as generating capacity. The expected shortfall in reliable generating capacity has been caused, in part, by a lack of commitment to a balanced portfolio of generation, storage and network investment.
"Adding more electricity storage into the power system will bring real long term benefits."
Sounds like a good bet for investors to me.