PVbatteriesA 2014 study estimates that cheap batteries paired with rooftop solar panels may make economic sense very soon, if not now.   By as soon as 2020, the .”The Economics of Grid Defection” report authored by the reputable Rocky Mountain Institute estimates that tens of millions of businesses and homeowners in California and New York may be able to combine solar panels, batteries and sometimes a backup diesel generator to get local electricity cheaper than that sold by utilities.  It goes on to note that solar power plus batteries and diesel backup is already cheaper than grid power for some commercial buildings in Hawaii, which has the highest electricity rates in the country.  So, is now the time to invest in battery backup along with your PV solar array and tell the local utility to “disengage”?

Probably not, but possibly soon.   There have been some new developments in battery technology that suggest soon may be sooner than the utilities like to contemplate.   Tesla has recently made a splash introduction of  “next generation lithium-ion batteries” produced in a Nevada-based “gigafactory”.    Tesla introduced its “Powerwall Home Battery” priced at $3500 for a 10kWhr system.   (Costs may be lowered by local subsidies from governments and utility companies.)  They are a slim six inches thick and can be mounted on walls. They’ll be sold by Tesla Energy later in 2015, although they are reportedly back-ordered until 2016.    At $350 per kWh, the 10 kWh Powerwall beats the leading competition handily. A January, 2015, report from Moody’s pegs the average cost of batteries at $500 to $600 per kWh . But in addition to the PowerWall, you need a DC/AC inverter, and professional installation of the system, which could add a few thousand dollars to your total cost.   Still, Powerwall is very exciting largely because degree to which industry experts got their predictions wrong is indicative of the incredible progress being made in the energy storage industry.  Many in the industry predicted prices of $10,000 as a best-case scenario.  While the Powerwall is still not cost-effective enough to cause mass defection from the grid, it highlights the huge and attainable potential of energy storage technology.   More importantly, it’s not the only major development.

There are other developments that haven’t received as much attention.  In Fall 2014,  the journal Nature published a study that described a new liquid battery has a negative electrode made of lead, which is cheap and melts easily, mixed with a dash of antimony to boost performance.   It asserts that “that alloying a high-melting-point, high-voltage metal (antimony) with a low-melting-point, low-cost metal (lead) advantageously decreases the operating temperature while maintaining a high cell voltage.” Commercial application of this new battery will be field-tested this year and may be manufactured for sale as soon as 2015.    Another field test is taking place at a small solar power plant near Modesto, in California’s Central Valley where a startup called Enervault recently unveiled battery technology that could increase the amount of renewable energy utilities can use.  The technology is based on inexpensive materials that researchers had largely given up on because batteries of their short lives.   However, Enervault claims it has learned to how to extend the operating life of the batteries.

More exciting news comes out of Ohio State University which announced in October 2014 that it had patented a battery that recharges tnself using solar power.   Effectively, it is an integration of two technologies:  a solar panel and a battery.   This version appears to achieve much higher efficiencies than had been accomplished in earlier versions.    This new solar battery could make it more affordable for homeowners and businesses to use solar energy rather than less sustainable sources of power.  The University estimates it could reduce energy costs by 25%.

Some other companies pioneering battery storage in California include Coda, which focuses on larger customers, as well as startups like Stem and Green Charge Networks, which have signed up multi-million-dollar financing for their behind-the-meter batteries. Another large player is SolarCity, which has partnered with Tesla to supply batteries for commercial buildings.

Airlight Energy, a Swiss supplier of solar technology, claims to be working with IBM to perfect a 10-meter-high solar “sunflower.” A 40-square-meter parabolic dish made of a patented “fiber-based concrete” concentrates the sun’s radiation 2,000 times onto photovoltaic panels, converting 80% into 12 Kw of electricity and 20 Kw of heat. In theory, the system can also be customized to provide drinkable water, air conditioning or desalination from its hot water output.

SunEdison has announced a production breakthrough that can slash the cost of the high-purity polysilicon used for solar panels. Called “high pressure fluidized bed reactor” (HP-FBR), the method is reportedly 10 times more efficient while using 90% less energy. If it is adopted at scale, it could make solar power the lowest cost way to generate electricity.

GTM Research anticipates that distributed storage in the U.S. will grow to more than 700 megawatts in the next six years, partly driven by solar installers who can monetize batteries.  SunPower execs suggest that this may be happening in the next five years — although this may be overly optimistic.  Another long-time solar advocate, Jigar Shah, is quoted as being doubtful that installers and service providers are internally equipped to handle the complexities of storage regulation.  And yet, mainstream companies such as Panasonic are offering storage batteries for residences.

So, for some ambitious homeowners, the time for storage/PV may be now.   But for most, it may not be until around 2020, but Tesla is attempting to jump-start the market now.   Stay tuned.