By Michael Kluk and Leslie Crenna

Portable, solar-powered batteries can provide a measure of safety and resilience in the event the power grid goes down and they’re a great way to avoid polluting, fossil-fuel powered generators. These batteries eliminate messy liquid fuel, relying instead on the sun or a wall plug, and there’s no direct odor or health hazard associated with emissions.

Portable, solar-powered batteries can also serve as a primary supply while camping, RVing, or van touring, eliminating those terrible combustion engine sounds while out in nature. Even though portable solar-powered batteries have much less capacity than a hard-wired solar battery associated with a rooftop solar system, these devices provide a relatively cost-effective degree of protection in the event of a power outage.

While lithium ion batteries are the best we’ve got at the moment, emerging technologies appear to be more efficient than lithium ion, such as lithium-ion phosphate batteries. Alternatives, such as sodium-sulphur based batteries, a type of molten salt that can be processed from sea water, are very promising in the fight to reduce mining impacts on land and the deep sea.

Powering the fridge is key during an outage

Cheryl Berry is currently a Davis resident at Rancho Yolo Retirement Community, but in 2019 she was living in Novato. The Kincaid Fire in the fall of that year knocked out power in her neighborhood for several days. Fortunately, she had purchased a storage battery, a 4Patriot 1800, earlier that year complete with a set of solar panels. The battery was able to keep her refrigerator operating for three days during the outage. The solar panels charged the battery, extending the time it was able to keep the refrigerator functioning, but after three days were not able to keep up with demand. Cheryl was able to plug in and re-charge the battery at a friend’s house across town where there was still power. Charging the battery with AC took only about two hours and the refrigerator operated for another day until her power came back on.

Cheryl was so impressed with the resiliency offered by a storage battery that she purchased a second one this year. This time she purchased an Energizer Power Source Pro. She is impressed with the improvements in the technology.

While Cheryl’s first 4Patriot purchase was $3,000 in 2019, weighing in at 46 pounds and a 5.4 amp hours capacity, Cheryl describes the 240 watt solar panels that came with the unit as heavy, glass covered, and hard to manage.

Her newer Energizer is much lighter, 23 pounds, with more capacity, 8.25 amp hours, and it was substantially cheaper at $1200. The solar 200 watt panel that comes with it is on a plastic backing, light and foldable. An additional 200 watt solar panel can be added for $200. According to the manufacturer, the battery can charge in seven hours with the 200 watt solar panel and under two hours using AC.

Medical devices powered for several days

Kunzang Roesler and J.B. Colson live in Rancho Yolo in Davis, too. They each use medical devices that require a regular source of power at night. Power outages, even for a short period of time, are more than an inconvenience. To ensure dependable power, they were each gifted a portable lithium-ion backup battery, a Goal Zero Yeti 1500X. This particular model, which retails for $1300, is mid-range with other portable batteries by the same manufacturer having more and less capacity. It is heavy, weighing 46.5 pounds but a wheeled cart is available making it easy to move around. A quick internet search for “portable battery backup solar power” reveals more than a dozen manufacturers of similar products. There is no shortage of options.

Kunzang and J.B. keep their batteries charged from the grid (plugged into the wall) and use them as emergency power only in the event of a power loss. According to the manufacturer, fully charging the 1500X will take about 14 hours from a standard 110 volt wall socket. A variety of solar panel options are also available. A 100 watt panel will fully charge the 1500X in 25 to 50 hours of sun exposure. Charging with a 600 watt setup will take from 6 to 12 hours. The battery has a capacity of 14 amp hours.

It has seven different port options including fast-charging 60 watt USB-C Power Delivery, multiple USB-A ports, regulated 12V, and two 120V AC ports. According to the manufacturer, it has the capacity to recharge a laptop 31 times, power a 11 watt lightbulb for 138 hours (LED assumedly), or a modest but full sized refrigerator for 21 hours. Kunzang and JB have found it capable of powering their medical devices for several nights or their refrigerator for a day.

Kunzang and J.B. are grateful to Angie Guerrero, Disaster Preparedness Coordinator for Resources for Independent Living (RIL), for “rustling up” the funds to make their peace of mind and better health possible.

Stationary rooftop solar backup battery systems

Portable batteries have much less capacity than the fixed solar batteries installed permanently in conjunction with a rooftop solar system. Batteries associated with rooftop systems usually have an amp hour capacity in the range of 1,200 amp hours and a hefty price tag in the $7000 to $10000 price range. For comparison, the largest battery in the Goal Zero portable series has a capacity of 31 amp hours and costs $3,200.

Local companies getting into the mix

Cool Davis photographer Johan Verink (who does not live in Rancho Yolo) has been experimenting with a portable solar-powered battery from a local company, California Sunlight. Johan reports that “within half a year, I have not seen a specific power capacity loss, but I am still learning, investigating and learning things that I did not know.”

California Sunlight sells several models including foldable solar panels for collecting energy from the sun. Some batteries are lighter than others; the heavier models include wheels and handles. Founded in 2010, California Sunlight Corporation develops, designs, and commercializes these integrated solar energy systems.

Alternative lithium batteries

Lithium-ion batteries require less maintenance and are currently cheaper than alternatives, but mining and processing causes significant environmental harm to soil, water, and humans. Lithium-ion batteries are also prone to overheating and in some cases can cause electrical fires. The 2023 documentary film “Deep Rising” (not to be confused with the 1998 horror film) chronicles the current metals rush happening in the deep sea floor, partly driven by the high demand for metals such as lithium for batteries.

According to Google, lithium-ion phosphate batteries (LiFePO4) have a longer lifespan than lithium-ion versions and they are more stable. Brands include, Li Time, Eco-Worthy, CHINS, and Redodo on Amazon.

Low impact saltwater batteries

A retired wastewater engineer, Johan has also been investigating sea salt based batteries. He understands that “in the lab, a sea salt battery has been charged and recharged 64000 times without significant capacity loss from 0 to 100 percent, and can be charged straight from solar panels. I have a prototype sea salt battery and am working on how to best monitor it by hand, but hopefully soon also by computer.” Sea salt batteries have no fire risk.

According to Energy Sage, “saltwater batteries don’t use the same toxic metals and materials that most lead-acid or lithium-ion batteries use,” they’re easy to recycle, and they last longer than many other battery options on the market. However, because they have a lower energy density, they need to be larger, and are more expensive to produce. Bill Gates backed start up Aquion, which was unable to scale up and filed bankruptcy in 2017.

According to, a significant breakthrough late in 2022, produced a sea salt battery with four times the capacity of a lithium version: “Constructed from sodium-sulphur – a type of molten salt that can be processed from sea water – the battery is low-cost and more environmentally friendly than existing options.” Another quick search revealed a Chinese car manufacturer marketing an electric vehicle with a sodium ion battery.

More research is needed, but salt based batteries hold huge promise to power society without the significant repercussions.

Images of sealife that would be impacted by deep sea mining. Capture from “Deep Rising” (2023)


Images of whales amongst the equipment associated with deep sea mining. Capture from “Deep Rising” (2023)

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