One of the problems with renewable energy is that the main contenders and the cheapest options—wind and solar—are intermittent. Is there a way to get around this problem?
And not only intermittent–they don’t produce dispatchable power. This inherent flaw has led many fossil-fuel defenders to argue that renewable energy will always need substantial backup from natural gas power plants, and that the cost of the backup system should be included in the assessment of solar and wind—essentially rendering them more expensive compared to fossil-fuel alternatives.
Enter the trifecta
When utility-scale photovolatic energy and wind power are combined with with energy storage systems (ESS – a.k.a. batteries) the picture changes radically. When Bloomberg NEF published its New Energy Outlook 2018 last month, one key message was emphatic: “Wind and solar are set to surge to almost ’50 by 50’—50% of world generation by 2050 – on the back of precipitous reductions in cost and the advent of cheaper and cheaper batteries that will enable electricity to be stored and discharged to meet shifts in demand and supply.”
The cost of wind power, utility-scale PV , and megawatt-level energy storage systems are falling dramatically. Cheap renewable energy and batteries fundamentally reshape the electricity system–as the cheap batteries enable solar and wind to run when the wind isn’t blowing and the sun isn’t shining. Most importantly, utility scale batteries provide dispatchable power.
This is the key to unlocking the enormous potential of renewable energy. The Bloomberg report calls this combination the PV, wind and batteries trifecta—meaning a 1-2-3 winning combination 
Utility scale Lithium-ion batteries are becoming larger, less expensive and more reliable. The largest system may be Tesla’s 100 MW Li-ion battery in South Australia . Closer to home, in February this year, Arizona Public Service announced that it will install a 50 MW/135 MWH battery to help shift the output of a 65 MW solar farm to deliver power in the evening—when solar energy drops off. And in May, Tucson Electric Power inked a deal for 100 MW of solar and a 120 MWh battery system for less than 4.5 cents/kWh over 20 years . In Puerto Rico, an RFQ was issued earlier this year for 10 20-MW/20 MWh battery energy storage systems to be integrated into the national power grid. If necessary, the 10 energy storage systems will be able to expand to 40 MW/160 MWh capacity.
The Haitian Connection
Batteries work brilliantly at the household level too. When I last lived in Haiti, we had electricity only for a couple of hours twice a day. The power supply in Haiti is definitely an intermittent source of energy.
Many of the houses and apartments in Petionville have batteries that store electricity when there’s power from the grid. A small inverter charges the batteries, and when the electricity cuts out, it converts the direct current from the batteries into 120 volt AC to run the lights, fans, the TV and appliances. The inverter is generally a 24-volt unit so the large 6-volt batteries are connected in multiples of 4. I had 12 heavy batteries hooked up in my house in Petionville.
Many houses and apartment blocks also have a diesel generator installed as backup in case the power goes off for more than a day.
But I had carried with me to Haiti a set of eight old Arco Solar photovoltaic panels. Set out almost flat on the roof of the house and run through a small charge controller, the sun topped up the batteries even when Electricité d’Haiti was MIA.
I never needed to run the generator. The combination of PV power and batteries completely solved the intermittency problem.
California follows suit
Jerry Brown gets it.
In May this year, the California Energy Commission voted unanimously to update the state’s building code to require rooftop solar panels on all new apartment buildings and condo construction starting on January 1, 2020.  Batteries are not mandatory, but in the US they qualify for the solar Investment Tax Credit (ITC)—and California has been providing incentives for home batteries since 2001. Whether it makes sense to install batteries in a residence with solar panels depends on the economics. But there are advantages for both the home owner and the utility. If necessary, home owners can top up their batteries at night when tariffs are lower; and the utility has customers with a much flatter and more predictable demand profile.
Batteries can also feed electricity back into the grid. By 2030, according to the Bloomberg analysis, the configuration of many systems will be characterized by PV that meets daytime demand, and batteries that absorb excess generation and discharge at high-value periods when renewables may be powering down–particularly in the evening.
And then there’s the resilience question. Hurricanes, wildfires, floods, and storm surge—are you sure your local power company will manage to keep you powered up? Severe weather is now the leading cause of power outages in north America.
In Florida they know a thing or two about extreme weather. The SunSmart Emergency Shelter Program has installed solar PV systems with battery storage in well over 100 schools to create emergency shelters throughout the state..
Batteries in the basement and solar panels on the roof is what keeps buildings up and running. In Australia, distributed solar with battery storage has becomes cheaper than electricity from the grid in several regions. In 2017, an estimated 40% of new rooftop solar installations included energy storage—amounting to over 20,000 installations, mostly in the residential sector. Interest is also rising in the US with some developers predicting a fourfold increase in residential energy storage in 2018—most of it tied to rooftop solar.
With MW-scale energy storage systems coupled up, wind farms and photovoltaic power plants are no longer intermittent. They are dispatchable.
So energy storage systems don’t just unlock the inexhaustible potential of solar energy and wind power. They are also the key to substantially reducing emissions of greenhouse gases.
A perfect trifecta.
 See : Tesla’s enormous battery in Australia just weeks old, is already responding to outages in ‘record’ time. At: //www.washingtonpost.com/news/the-switch-wp/2017/12/26/teslas-enormous-battery-in-australia-just-weeks-old-is-already-responding-to-outages-in-record-time/
 See: APS to install 50MW, 135 MWH solar-shifting battery. At: //www.utilitydive.com/news/aps-to-install-50-mw-135-mwh-solar-shifting-battery/516850/
 See: Elon musk’s unprecedented solar+storage vision for Puerto Rico moves forward. At: //pv-magazine-usa.com/2018/06/28/elon-musks-unprecedented-solarstorage-vision-for-puerto-rico-moves-forward/
 See: California home battery rebate: Self-Generation Incentive program (SGIP) explained. At: //news.energysage.com/california-energy-storage-incentives-sgip-explained/
 See the Bloomberg New Energy Outlook overview cited above
 See the Florida Solar Energy Center presentation at : //www.cleanegroup.org/wp-content/uploads/ESTAP-webinar-slides-10.24.17.pdf
 The numbers are from the Renewables 2018 Global status report available at: //www.ren21.net/status-of-renewables/global-status-report/
 See: Residential storage faces sunny prospects this year. At: //www.utilitydive.com/news/residential-storage-faces-sunny-prospects-this-year/520966/
Breaking news, see : PG&E proposes plan for 567 MW of energy storage. At: //www.renewableenergyworld.com/articles/2018/07/pge-proposes-plan-for-567-mw-of-energy-storage.html