Hurricane Ian's catastrophic winds and flooding could cause prolonged power outages across large parts of Florida. The storm is the latest in a series of storms and extreme heat and cold that have knocked out power for several days for millions of Americans in recent years.
In many disaster- and blackout-prone areas, people are beginning to think that investing in rooftop batteries and solar power systems can keep the lights and air conditioning on when the grid is down.
When the grid goes down, most solar systems without batteries also fail. But a house with batteries can go off the grid. The sun supplies energy to the house every day and recharges the batteries that provide energy at night.
Our Berkeley Lab team researched what it would take for homes and commercial buildings to avoid power outages of three days or more with solar and batteries.
How Much Can Solar + Storage Do?
For the new report, we modeled total power outages for every US state, including a rooftop solar system with a 10 or 30 kWh battery for cooling, lighting, Internet services and more. We checked that it can drive critical loads like . : pumps; if it could go further, also electric heating and air conditioning; or if he could supply the whole house.
To put this in perspective, the Tesla Powerwall, the most popular battery on the market, has a storage capacity of just over 13 kWh.
Overall, we've found that even a modest solar system and a single battery can power critical household loads for days almost anywhere in the country.
But our charts show that cooling and heating backups can be difficult, but not insurmountable. Homes in the Pacific Southeast and Northwest often have electric resistance heaters that survive solar power and storage during winter downtime. Homes with efficient heat pumps fared better. Summer air conditioning loads can be heavy in the Southwest, making it difficult to meet all cooling and solar storage needs during summer downtime.
Solar systems and larger batteries can help, but meeting demand during outages still depends on weather, home energy efficiency and other factors. For example, during a power outage, simple thermostat adjustments reduce heating and cooling needs and allow the solar array to store energy for longer.
Energy availability for commercial buildings varies greatly depending on the type of building. Schools and large retail stores that have enough solar roof space to meet the building's electrical needs are much better than energy-intensive high-rises such as hospitals.
How would the sun react to the past 10 disasters?
We also looked at 10 actual outage events from 2017 to 2020, including hurricanes, fires and hurricanes, and modeled building performance for specific locations and actual weather conditions during and after outages.
We found that in seven outages, most homes would be able to supply critical loads, as well as heating and cooling, using 30 kWh of storage or a little more than two Powerwalls of solar.
But the air around the current can have a big impact, especially on hurricanes. In 2018, after Hurricane Florence knocked out power in North Carolina, three days of cloudy skies covered or even halted solar panel production.
On the other hand, Hurricane Harvey hit the Texas coast in August 2017 but continued to cause widespread destruction in other parts of Texas. The skies cleared on Corpus Domini, although it took a week or so to restore power. Therefore, solar power and storage will be a big help, providing almost all the energy needs of a typical family when the sky is open.
Likewise, we've found that solar power can work well in low-cloud events, such as fire suppression in California or the aftermath of a 2020 Iowa windstorm.
The source of heat in the house is also an important factor. Five to 10 days after the 2020 Oklahoma ice storm, we found that solar power and a 30 kWh battery could provide almost all the power and heat needed for homes heated with natural gas or heat pumps. But electrically heated houses will fly.
More than half of Texas homes are heated by electricity, mostly resistance. Energy Star heat pumps provide both heating and cooling and use half the electricity per unit of heat energy than electric resistance heaters and also cool more efficiently than the average new air conditioner. Converting old resistance heaters to new heat pumps can not only save money and reduce peak demand, but also increase resilience during outages.
New backup modules
Installing solar power and storage to provide backup power for a home or building requires additional work and higher costs; A Powerwall alone can cost anywhere from $12,000 to $16,500 for a complete system installation before rebates and taxes. That's about the size of a decent sized solar system. However, an increasing number of hosts are installing both.
By 2021, more than 90% of new solar installations in Hawaii will be battery-connected after the rule change. Now these distributed power plants provide power to the grid as coal-fired plants are retired.
California has more than 1.5 million solar power systems. A growing number of customers are retrofitting batteries to their systems or adding new solar storage, in part because utilities use "public safety outages" to reduce the risk of power line fires on dry, foggy days.
New forms of energy storage are emerging, especially from electric cars. Ford is working with SunRun to connect its new F150 Lightning electric truck to a solar-powered two-way charger that can use the truck's battery to power the home. The standard version of the truck is equipped with a 98 kWh battery, equivalent to more than seven Tesla Powerwall stationary batteries.
Critical capability for critical services
A firehouse in Puerto Rico shows what solar power and storage can do. After Hurricane Maria knocked out power for several months in 2017, the island installed more than 40,000 solar power systems, often combined with battery storage. One of them is located at the Guanica fire station, which was unable to receive emergency calls during previous outages.
In September 2022, the fire station was still operating when winds and floods from Hurricane Fiona knocked out power to much of Puerto Rico again.
"The solar system works beautifully." Sergeant Luis Saez spoke to Canary Media a day after Fiona's powers were taken away. "We didn't lose our energy during the storm."
This article was republished by The Conversation, a non-profit independent news website dedicated to sharing the opinions of academic experts. Author: Will Gorman, Lawrence Berkeley National Laboratory ; Bentham Paulos, Lawrence Berkeley National Laboratory and Galen Barbose, Lawrence Berkeley National Laboratory . If you are interested, you can subscribe to our weekly newsletter.
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Will Gorman receives funding from the US Department of Energy.
Bentham Paulus received funding for this work from the US Department of Energy.
Galen Barbose receives funding from the US Department of Energy.
