I’m Charging All My Gadgets With a DIY Solar Microgrid

My laptop, Kindle, and toothbrush run on California sunshine

All images courtesy of the author.

What would you do if your power went out for three to four days at a time, several times per year? My slice of the San Francisco Bay Area is subject to Public Safety Power Shutoffs (PSPSs), where our utility (PG&E) kills the power to whole communities for days at a time in order to prevent deadly wildfires. I know the shutoffs are an essential safety measure, but they’re also incredibly disruptive. In 2019, the town where I live lost power for several three- to four-day stretches.

To weather these shutoffs, I built a private DIY solar microgrid. It supplies off-grid power even in the midst of a shutoff.

My microgrid has been extremely helpful for running basic lights and appliances during power outages. But after building it, I started to wonder what would be the most impactful way to utilize its power during an outage, both for basics and to maintain productivity. Especially now that I am working exclusively from home? And how could I put it to productive use during the hundreds of days per year when grid power is running fine?

I’ve tried using my microgrid to mine cryptocurrency (more on that soon). But after a lot of experimentation, I found the absolute best use for its power: I use it to charge my gadgets. All of them — from my laptop to my Kindle to my toothbrush.

Why gadgets? Because these devices have an outsized impact on our daily lives, safety, and productivity. Yet at the same time, they’re small and energy-efficient, which means you get a lot of bang for your solar power buck. With a fully charged phone, laptop, camera, wireless hotspot, and several battery-powered lights, I can work, get crucial safety messages (or call for help), access entertainment, and navigate my home after dark even during an outage.

Here’s how I turned my solar microgrid into a giant gadget charger — and how I’m using it in both good times and bad ones.

The microgrid

My microgrid itself is built around off-grid solar panels from Renogy. The company’s panels are usually used for RVs, boats, remote cabins, weather monitoring equipment, and other applications with no access to a traditional electric grid. I have a 100-watt, 12-volt panel, as well as three 50-watt, 12-volt panels. This gives my system a nominal capacity of 250 watts though, in reality, it generates more like 170 in direct sunlight.

The panels are wired up in parallel using a four-way MC4 splitter, which keeps their voltage constant while combining their wattage. The power from the panels flows into a Renogy Adventurer charge controller, which takes the panels’ power and uses it to charge a large battery. I originally used a car battery, but enough people on the internet yelled at me about this that I switched to a dedicated Renogy deep-cycle solar battery. The battery is sealed, so I don’t have to worry about sloshing acid, and it’s designed to be charged and discharged over and over for years. It holds 100 amp-hours of charge.

The battery then connects to a 500-watt Renogy power inverter (Renogy since replaced it with a 700-watt model), which takes the microgrid’s 12 volt DC power and transforms it into the 120 volt AC power used in American homes. My microgrid is installed against the back fence in my yard. It gets three to four hours of direct sun per day and another three hours of indirect sun, generating around 800 watt-hours of power per day. It cost me about $1,000 to build.

Delivery

When I first built my microgrid, I set it up as its own self-contained unit outside. During an outage, I would run a long extension cord from the inverter into an open door of my house and use it to run a few appliances. That worked, but it wasn’t ideal. Many PSPSs last eight to 12 hours — long enough to be disruptive, but not necessarily long enough to warrant hauling out extension cords and running them around my home. It also didn’t provide an easy way to use the microgrid’s power during normal times.

When I moved to a new home last year, I set things up differently. After installing my microgrid, I got a 120-foot extension cord and ran it from the microgrid in my backyard around the base of my home, and under my garage door into my garage. I used U-shaped fasteners to secure the cord along its path, and buried a portion of it in a trench so it wouldn’t be a tripping hazard.

The cord’s first terminus is next to my workbench in the garage. It’s plugged into an in-line GFCI circuit breaker for safety, and then into a Kill-a-Watt meter so I can monitor how much off-grid power I’m using. It ends with a plug strip, which I use to charge gadgets that I want to keep in the garage, like a power drill and Dyson vacuum cleaner.

A second extension cord then carries power into my house, traveling through a groove under the weather-stripping for an interior door, behind a table in my living room, into my office, and into a second plug strip anchored to an Ikea organizer. This plug strip has an Anker four-port fast charger with several USB charging cables, a Panasonic AA battery charger, as well as several proprietary chargers for various devices. I connected all the cables together with Velcro wraps, and they travel together into the back of a Target cube organizer, where each cable is separated out and held down with gaffer’s tape.

When I want to charge any device from the microgrid, all I have to do is plunk it down in one of the cubes of the organizer, choose the right charging cable, and connect it to the device. The microgrid is totally isolated from the structure and electrical system of my home, which is important for safety. But using its power on a daily basis is as simple as walking into my office and plugging a gadget in.

The gadgets

What do I charge from my microgrid? Everything. On a regular basis, I use my grid to charge a Samsung Galaxy S10 phone, my iPad, a Chromebook, my Kindle Oasis, the batteries for my Leica Q camera, my Fitbit Sense smartwatch, a video light, the Dyson vacuum, and power drill in the garage, a GoPro HERO 7, and my Samsung Galaxy Buds+ wireless headphones.

In terms of safety equipment, I also keep a WSKY lantern fully charged at all times, and my Panasonic AA battery charger on the second plug strip always has four AA batteries ready to go, which I can use in my Thrunite Archer flashlight or a portable emergency radio in the event of a PSPS. I also keep a Tacklife T8 battery pack fully charged in the garage, which I can use to jumpstart my car in an emergency, or can use as a portable power pack and flashlight around my house during an outage. The T8 can even power a small portable heater, which I can use to warm up a room if an outage occurs during cold weather.

I admit that I’ve gotten a little carried away with charging devices using off-grid solar power. I’ve experimented with charging my Philips Sonicare wireless toothbrush from the microgrid, for example. This hardly qualifies as essential emergency equipment, but it had a charger, so I figured I’d plug it in and add it to the mix.

One of the nice things about my setup is that it allows me to charge devices at a low voltage using the Anker charger or their own proprietary chargers, but since the microgrid operates at 120 volts, I can also plug standard household appliances into the plug strip in my office and run them on solar power. My Comcast modem, for example, draws about 20 watts or around 500 watt-hours per day. With an 800 watt-hour per day generation capacity from my panels as well as my Renogy solar battery (which holds 1,200 watt-hours), I can easily run the modem from the microgrid for days. In a pinch, I could even run my main work computer (which draws around 200 watts) off it for a few hours.

During a PSPS, this gives me a great deal of flexibility to continue working and remain productive. My modem is designed to “fail over” to a Cradlepoint cellular hotspot connection if the Comcast cable line goes out, so even in the middle of a long outage, my microgrid would allow me to run the modem and hotspot off solar power 24/7, keeping me connected to the internet. Pairing the modem with my Chromebook over Wi-Fi, I could keep working indefinitely, even if the lights went out. Since I’m now working exclusively at home, the ability to remain productive despite blackouts is huge for the continuity of my business. If all that fancy tech failed, I could always use the hotspot on my microgrid-charged cellphone to stay online, too.

Results

On a normal day (without the Comcast modem connected to the microgrid), charging my gadgets uses about 10–30 watts at any given time. That’s less than 700 watt-hours per day, or well below the generation capacity of my solar panels. That means I can charge my gadgets from the panels indefinitely. And if there are a few rainy or overcast days, it’s fine — with 1,200 watt-hours of capacity, the Renogy battery would keep my gadgets charging for almost two full days with no sun at all.

Because my off-grid system cost about $1,000 to build, I’m unlikely to break even financially on the power it generates any time soon. Even with PGE’s super-high marginal rate for electricity of around $0.34 per KWH, my system only generates about $0.224 per day worth of power. That means it would take almost five years of charging for me to break even on the system’s costs.

What the system lacks economically, though, it more than makes up for in increased safety and self-reliance for my family. It’s nice to know that because I charge all my devices from the microgrid on a daily basis, even during a PSPS I wouldn’t need to alter my daily routine in order to keep all my gadgets and safety equipment charged up. I could walk into my office and grab whatever gadget I need from its Target cube, just as I do every day.

I’ve also found that there’s a weird sense of artisan pride in generating our own power at home. Just as many people enjoy growing their own fruits and veggies — even though they can get produce cheaper at the supermarket — I like the feeling of picking up my phone, reading a book on my Kindle, or using my toothbrush and knowing that all these gadgets are powered by California sunshine harvested in my own backyard.

If you live in an area affected by PSPSs — or one with an unstable power grid — you should consider investing in your own DIY microgrid. Ideally, it’s best to buy and install your microgrid before fire season arrives, as equipment can begin to sell out once PSPSs happen. Even if you don’t live in an area with planned shutoffs, though, you should still consider building your own microgrid.

Natural disasters can happen at any time, and there’s a great deal of comfort in knowing you can still work, light your home, and yes, even play Candy Crush if the lights go out. You don’t need to build a system as ambitious as mine to get started — stand-alone systems like Renogy’s Phoenix Elite give you a few hundred watt-hours of generation capacity in an easy-to-you, portable package which you can extend with more panels down the line.

Maybe you don’t really need a solar-powered toothbrush. But the peace of mind of knowing you can use essential gadgets and safety equipment during an outage is well worth the investment of building an off-grid charging system.

Co-Founder & CEO of Gado Images. I write, speak and consult about tech, privacy, AI and photography. tom@gadoimages.com

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