Why solar backup power is better for the planet and your health

Instead, she and other experts recommend investing in more planet-friendly sources of backup power, namely solar and battery technology. These units can range from portable solar-powered batteries to larger home setups involving rooftop solar panels connected to battery storage systems. Depending on the technology and how much energy you’re using, some of these systems can power an entire home for days during blackouts. They can also provide year-round benefits, including lower utility costs.

“A gas backup generator for your home is like an insurance policy where it doesn’t provide any value until you have a very bad day,” said Mark Dyson, managing director of carbon-free electricity at the energy think tank RMI. “Other solutions that we’re interested in exploring — like solar plus storage, for example — save money every day and then also provide backup in an emergency.”

We looked at how solar-powered batteries stack up against traditional fossil-fuel generators. Here’s what you need to know.

The size of a generator or battery backup depends on how much power you need, said Noah Kittner, an energy systems expert and assistant professor at the University of North Carolina at Chapel Hill.

These are the oldest and most common type of generators. They run on different fuel types, including diesel, propane and natural gas, and can be portable or permanently installed.

You can use them to provide power to various electronics, larger appliances and entire homes. The number of appliances a fuel generator can power depends on its size, power output and how much fuel you have.

Batteries also come in a variety of sizes and can be portable or installed. Smaller batteries could be enough to keep a small electric fan going, charge cellphones or power a radio.

For a refrigerator, you may want at least eight to 12 hours of backup power, Kittner said. Common rechargeable lithium-ion batteries sized for homes can generally provide this amount of power.

Stand-alone batteries are time-limited, Dyson said. Even larger ones could run out of juice fairly quickly if you’re using them to power appliances that draw a lot of energy, such as stoves or air conditioners. That means if you’re using these batteries during a blackout, once they run out you would need to wait for the power to come back on or find another way to charge them.

Portable batteries, which also vary in their power output, can come equipped with small solar panels, so they can be charged without being plugged in. If the battery is fully drained, it could take several hours to recharge using solar power.

You can also have larger systems with rooftop solar panels connected to battery storage systems. These residential setups can benefit homeowners even when the power isn’t out, said Z. Smith, principal and director of sustainability and building performance at EskewDumezRipple, an architecture firm with offices in New Orleans and Washington, D.C.

“The economics of a battery and solar system, you get benefit all the time, whereas the generator is a dead loss and its benefit is only there during the power outage,” Smith said.

Rooftop solar and storage systems are wired directly into home electricity systems, Dyson said. Most portable batteries hook up to individual appliances directly or with extension cords. Similar to a fossil-fuel-based backup generator, some larger batteries can be hooked up using transfer switches, which connect them to your electrical panel, he said. When the power goes out, the switch lets your home draw power from your backup source instead of from the power grid.

Emergency power sources can be more effective if your home is well insulated and weatherized to prevent air leakages, Dyson said.

Regardless of the type of backup power you have, be mindful of your energy use during blackouts, Burke said.

“It’s typically necessary to … be judicious with how you’re using your energy in your home,” she said. “You wouldn’t run the dishwasher, your washer and dryer, everything in the house all at one time. These are emergency circumstances.”

Avoiding noxious, polluting fumes is one of the main advantages to not using fossil-fuel generators.

These generators produce exhaust that contains dangerous pollutants, including sulfur dioxide, nitrous oxide, particulates and carbon dioxide. Running them can also release carbon monoxide, an odorless, colorless gas that can kill people in minutes if it builds up indoors. The generators also tend to be noisy.

“One of the top concerns is about local air quality,” Burke said. “Imagine a neighborhood loses power and every house or every other house has some kind of fossil burning generation going all the time, it’s incredibly hot and humid — that all compounds into really bad ground-level ozone, which causes serious respiratory distress.”

You should never use fossil fuel burning generators inside your home or garage, even if the windows are left open. Place portable generators at least 20 feet from any residences, open windows or garages with the exhaust pointed away from homes, according to the Centers for Disease Control and Prevention.

“It’s key for people to understand that if they do this sort of informal thing of getting a gasoline generator and keeping it fed and putting it on their porch or something like that, you’re basically bringing in what could be a source of danger into or adjacent to your home,” Smith said.

The cost of any type of generator will depend, in part, on its size and technology, but prices can also vary among similar models.

For example, a portable 5,000-watt diesel generator, a common size that could be used for small homes, apartments and RVs, can cost anywhere from about $500 to more than $5,000. One model of solar-powered battery that can generate 5,000 watts continuously carries a price tag of about $4,700.

If you want a heftier and more permanent form of backup power, it will cost. The upfront price of installing a residential solar panel and battery storage system will be significantly higher than a similarly sized gasoline or diesel powered generator, Dyson said. But these systems can generate savings for homeowners in the longer term and there are federal tax incentives, and in some cases, no-money-down financing options, to help bring down the cost of the technology and installation.

“If you look at the value of just the solar, in most places in the country it pays back pretty quickly,” Dyson said. Storage batteries, he added, are also becoming more cost-effective.

Meanwhile, the cost to maintain and fuel standard generators can add up over time. Without regular maintenance, your generator might not work when you need it.

“The difference is that the diesel generator just sits there decaying, whereas the solar plus battery system is giving you value all the time and adding a battery can give you resilience,” Smith said.