Batteries Mean Actual Independence, Especially Off the Grid
The ancient Greeks told stories about harnessing the power of fire. Today, batteries accomplish that on a daily basis.
Eric MackContributing Editor
Eric Mack has been a CNET contributor since 2011. Eric and his family live 100% energy and water independent on his off-grid compound in the New Mexico desert. Eric uses his passion for writing about energy, renewables, science and climate to bring educational content to life on topics around the solar panel and deregulated energy industries. Eric helps consumers by demystifying solar, battery, renewable energy, energy choice concepts, and also reviews solar installers. Previously, Eric covered space, science, climate change and all things futuristic. His encrypted email for tips is firstname.lastname@example.org.
ExpertiseSolar, solar storage, space, science, climate change, deregulated energy, DIY solar panels, DIY off-grid life projects. CNET's "Living off the Grid" series. https://www.cnet.com/feature/home/energy-and-utilities/living-off-the-grid/Credentials
Finalist for the Nesta Tipping Point prize and a degree in broadcast journalism from the University of Missouri-Columbia.
This is sneakily one of the most important and underrated innovations of the modern era, allowing us to bottle up and take with us the energy that powers our work, our entertainment and even our transportation.
Combining battery storage with just a few hundred bucks' worth of solar panels, some wire and a couple of other inexpensive components means I no longer need to access the massive energy generation and transmission system that we call the electrical grid.
When living off grid, control over your home and life during the darkest and coldest times is tightly intertwined with the charge in your battery bank. Batteries are easily a key component of any off-grid energy system, but picking the right cells involves much more than just checking the specs.
Designing the 'good enough' battery system
There is, I suppose, a "right way" to design an off-grid solar power system with the ideal number and size of batteries to get you through long nights or a stormy spell without having to turn to a loud, stinky generator.
It starts with calculating the total amount of energy all your electrical devices draw, both on typical days and in peak usage scenarios. You'll need to factor in the wattage your solar panels can realistically generate in average, ideal and marginal situations. Then try to account for places where you'll lose some efficiency -- whether it's your system aging, long runs of wire, your inverter or any other places where electrons could leak.
All this helps determine the total capacity you want for your battery bank, but it's just the beginning of the things to consider. There are different types of batteries, from the old-school flooded lead acid batteries found in most conventional cars to the lithium units similar to those in our phones and electric vehicles. While lithium batteries are coming to dominate, they still have their downsides.
And this is to say nothing about determining what voltage is best for your system, whether you'll need both AC and DC circuits, how to follow local code, and exactly where you're going to set up the batteries, which tend to have very specific and important demands for their environment.
It's possible, of course, for trained professionals and even a committed DIYer to navigate all of this, determine the perfect batteries for their system and get them installed.
At least, I assume it was possible before March of 2020.
Power for a pandemic
I was putting together my family's solar and battery system mostly between May and June of 2020, when COVID lockdowns had already tied up supply chains and pretty much any professional willing to make a house call. Add the general uncertainty around employment, income and everything else in the world at the time, and it meant adopting an approach familiar to those in the tech industry: We would install the minimum viable product, or MVP, version of our solar system. We would start bare-bones to get up and running, and then adjust and upgrade as better components became available and affordable.
In other words, after designing what I thought was the perfect solar system, I had to start over from scratch when I started shopping and found supplies were limited. We also had a deadline to move out of the house we'd been renting the past five years. There was no turning back. Those early months of the pandemic were even more surreal for my family than many of our friends. There were showers taken in our swimsuits outside using a bag of lukewarm water hanging from a basketball goal and lights temporarily powered by a car battery that I would later recharge with my car. We were essentially camping rather than living in our new home.
That initial energy system was clearly minimal and obviously not viable. We quickly upgraded to a pair of big 6-volt flooded lead acid batteries, each weighing over 80 pounds and meant to power a golf cart. It was not ideal, but it was affordable, available and workable.
This technology has basically been the same for decades. These batteries are cheap, plentiful and reliable, especially in conditions like serious cold that render lithium units useless.
But they're also finicky and needy in their own ways. To get the best performance and long life out of lead acid batteries, they need to maintain a relatively consistent level of charge without getting too low or overcharging either. Like a campfire, they need a bit of tending to keep producing energy.
They also off-gas small amounts of hydrogen and are therefore best stored outside or in a well-ventilated space. Generally, they shouldn't be near your living areas, which means you have to create a separate one for them. I was forced to add this to my already very long pandemic DIY list.
Lithium love affair
Those golf cart batteries didn't last long, even though I eventually invested in another pair to double our battery bank and help get us through long winter nights. It's kind of like adding a big dry log to the flames, to belabor the campfire analogy.
The problem was that I really don't like running our generator. It disrupts our quiet neighborhood, pollutes pristine air and requires a walk outside and around the house to start it up.
So it shouldn't be a surprise that I didn't always run the beast to keep our batteries in the ideal range for state of charge -- I was not tending the "fire" as I should have. Under diligent care, the batteries should have lasted up to five years. Instead they were seriously degraded in half that time from a few years of pretty rough use.
Fortunately, by this time it was nearly 2023 and the world and its beleaguered supply chains had returned to something closer to normal. I jumped at the opportunity to replace those old golf cart juice boxes with some nice, new lithium units designed to last two to three times as long (for three times the cost). Even better, they require almost none of the constant attention to charge levels, don't off-gas, and prefer to be stored inside. Since they're also more compact and modular, it was easy to create an appropriate space for them.
Several months on, the results have been fantastic. Because lithium batteries can be taken down to nearly dead without doing extra damage (each charge cycle wears down batteries a tiny bit), I can get away with having half the capacity I did with lead-acid batteries, and each lithium battery is about a third the physical mass of its more archaic counterpart.
It's as if we finally have a campfire that needs no tending. Without the battery bank under my stairs, I wouldn't be living the same modern life as everyone reading this. I'd just be a guy camping inside his darkened house.