Hurricane Ian If the power grid is down can solar and batteries provide power to your home?

Hurricane Ian’s catastrophic winds and floods are expected to bring long-lasting power outages to large parts of Florida. The storm is the latest in the series of severe temperatures and cold weather events which have cut electricity to millions of Americans in recent years for days at a time.

In many outage-prone and disaster-prone regions, people are beginning to wonder if investing in rooftop solar or battery storage could help keep lights lit and air conditioning in operation when the power grid can’t.

If the grid is down, most solar systems that do not have batteries will shut down. With batteries, a home can be disconnected from the grid. Every morning, sun lights the home and charges up the batteries, which supply power through the night.

We Berkeley Lab team Berkeley Lab examined what it would be like for homes and commercial structures to withstand prolonged power outages lasting three or more days, with solar and batteries.

How much can solar + storage do?

For a new study we created an unavoidable power outage in every county across the U.S., testing whether rooftop solar systems with a 10- or 30-kilowatt-hour battery can supply power to vital loads like lighting, refrigeration internet service, and even well pumps. It was also determined if it could go further in powering heating and air conditioning; or if it could even power a whole home.

To put it in perspective The most well-known battery available The Tesla Powerwall, has just over 13 kWh of storage.

In general, we found that even a simple solar system and one battery could power vital loads in a home for days at a stretch almost everywhere in the nation.

But our maps demonstrate that providing backup power for heating and cooling can be difficult, but it’s not an insurmountable one. Homes in the Southeast and Pacific Northwest often have power-hogging electric resistance heaters, exceeding the capabilities of solar as well as storage during winter outages. Homes with efficient heat pumps performed better. The summer load of air conditioning can be heavy in the Southwest and makes it more difficult to meet all cooling needs with solar and storage in a summer blackout.

A larger array of solar and battery systems can help, but meeting demand for outages will depend on the weather, how energy efficient the home is, as well as other elements. For instance, simple thermostat adjustments during power outages can reduce heating and cooling needs and allow solar with storage to maintain backup power over longer time periods.

Solar and storage using a 10-kWh battery can supply power backup in many scenarios. Berkeley Lab, CC BY

The ability to power commercial buildings varies widely, dependent on the type of building. Schools and big-box retail stores that have enough roof space to allow solar power relative to the power requirements of the building are much more efficient than large, energy-intensive buildings such as hospitals.

How solar would have handled 10 disasters in the past?

We also looked at 10 real-world outage events occurring from 2017 to 2020, such as hurricanes, wildfires and storms, and also modeled the building’s performance for specific locations and real weather patterns during and after the outages.

We observed that during seven outages, most houses would have been in a position to sustain vital loads and heating and cooling using solar energy with 30 kWh storage, or about two Powerwalls.

But the weather that surrounds the outage can make a huge difference, especially for storms. Following Florence, the most powerful hurricane in history Florence destroyed power throughout North Carolina in 2018, cloudy skies hung around throughout three consecutive days dimming or cutting off solar panels’ power.

Harvey Harvey, on the other hand, struck on the Texas coastline in the month of August of 2017 but moved on to cause widespread damage elsewhere in Texas. The skies over Corpus Christi cleared even as it took a several weeks to restore power. Solar and storage would have been a big help in that case and could have provided all the power needs for the typical single-family home after the skies cleared.

What would a typical home have fared with solar power along with 30 kWh storage after the hurricanes Florence as well as Harvey. The blue light line indicates the short periods of ‘unserved load’, or shortfalls in meeting power demand following the storms. The state of charge indicates that batteries could stretch solar power into the night.  

FIND SOLAR SYSTEMS/BACKUP FOR YOUR HOME

Similar to solar, we have found that solar energy can be effective even in cloudy weather like the shutoffs for wildfire prevention in California and after the 2020 derecho storm in Iowa.

The source of heat for a home is also a key factor. In a 5-to-10-day power outage that followed an severe ice storm in Oklahoma in 2020 We found that solar power and a 30-kWh battery could have supplied almost all the critical power and heat needed for homes with heating systems that are powered by natural gas or. However, homes that have electronic resistance heating might have been short.

In Texas the majority houses are heated with electricity, primarily resistance heaters. Energy Star-rated heat pumps – which offer heating and cooling – consume half as much electricity per unit of heat output as electric resistance heaters. They they are more effective at cooling than the typical new air conditioner. Converting old resistance heaters to new heat pumps is not only able to only help save money and lower the demand for electricity, but also improve the resilience of your system during outages.

New forms of backup

Setting up solar and storage systems to supply backup power to the building or home takes additional effort and can cost more. One Powerwall will cost between $12,000 and $15,500 for a complete installation, before incentives and taxes. That’s as much as an average solar array. But, a growing percentage people are installing these.

Over 90% of new solar installations located in Hawaii from 2021 paired with batteries following a regulation change. The solar power stations are helping power the grid in the event that coal plants are decommissioned.

California has more than 1.5 million rooftop solar panels. A growing number of customers are retrofitting batteries to their systems, or adding solar and storage systems due to the fact that utilities have resorted to “public safety power shutoffs” to reduce the chance of wildfires sparked by power lines on dry, windy days.

Electric trucks and cars contain more battery storage than a Powerwall and hold potential as battery storage for future home batteries too. Ford

As well, new types for backup power is being developed particularly from electric vehicles. Ford is partnering with SunRun to integrate its brand new F150 Lightning electric pickup truck with solar power and a two-way charger that can use the truck’s battery to power a house. The basic version of the truck is equipped with a an 98-kWh battery. This is the equivalent of seven Tesla battery packs.

Critical power for critical services

A fire station located in Puerto Rico offers a glimpse of what solar and storage can accomplish. After Hurricane Maria interrupted power for months throughout 2017, nearly 4000 solar panels were put in place throughout the island, usually coupled with battery storage. One of them is located situated in the town of Guanica, in the town of Guanica which was unable to receive emergencies during previous outages.

When Hurricane Fiona’s wind and flooding again shut down electricity to the majority areas of Puerto Rico in September 2022, the fire station was still in operation.

“The solar system is working beautifully!” Sgt. Luis Saez told Canary Media the following day that Fiona destroyed power. “We did not lose power all throughout the hurricane.”

 

 

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