Solar is one of the most well-known renewable energy sources, but harnessing it for personal use has been difficult, especially if you're unable to install permanent panels on the top of your home. The EF ECOFLOW Solar Generator Delta Max and Solar Panel Bundle aim to change that, and it succeeds if your needs fall within its power output limitations. 

Before we get into the tech specs, it's important to report that this bundle costs $2,199 at the time this review is being published. That's a big investment to make, especially when you consider the fact that four rooftop solar panels can cost up to $400 less. The difference is that EF ECOFLOW's bundle includes an ultra-high-capacity battery to store the energy absorbed by the solar panel. The energy can be used immediately or saved for emergency situations or multi-day camping trips. This bundle may elicit some immediate sticker shock, but EF ECOFLOW has actually knocked $550 off its original price tag due a price reduction and free coupon provided when you shop on Amazon.

What is the EF ECOFLOW Delta Max Solar Generator Bundle?


Size: 19.6 H X 9.5 L 12 W Inches
Weight: 47.9 pounds
Capacity: 2,016 WH (watt hours)
Ports: Two USB-C, four USB-C, 2 DC, one car output, six AC outputs
Maximum Power Output: 2400W (watts)

EF ECOFLOW 220W Solar Panel
Size: 32.3 L x 72 W x 1 inches
Weight: 20.9 pounds
Maximum Power Output: 220W
Number of Panels: Four

My interest in solar energy has led me to trying out low-powered panels from companies like Grouphug and Anker, which are designed to charge portable electronics like a smartphone, tablets, or handheld game consoles. While impressive for their size, these solar panels lack the power output necessary to charge or run larger gadgets, be they laptops or small appliances. EF ECOFLOW's 220W solar panel can absorb and convert far more energy from the sun, and the Delta Max allows you to easily use it to power much more demanding gadgets. These are the most powerful sustainability tools I've tested in my career, and they've recalibrated my expectations for solar-powered technology in the future. 


If you've never used a solar panel before, you'll be happy to learn that EF ECOFLOW has made the setup process pretty painless. Using its instructions, I was able to set up the 220W Solar Panel and connect it to the Delta Max in about 20 minutes. It's important to recognize that I did need the help of a friend to set up the solar panel because it's several feet long when it's fully unfolded. This makes it unwieldy to move around as one person. You may be able to assemble it on your own if you lean the panel against the side of a house, or other tall, sturdy surface. 

Setting up EF ECOFLOW's solar panel had three basic steps: removing it from the included carrying case, unfolding it to reveal its four-panel array, and attaching the panel to its opened carrying case using a set of included clips and straps. That last step is what required me to seek a friend's help. The opened case acts as a stand for the solar panel, and angles it upward to absorb the sun's rays more effectively. Attaching the two pieces to one another is pretty simple because the solar panel has holes on its top and bottom edges, so you'll know the exact places to hook the case onto. I shouldn't have been surprised that EF ECOFLOW's solar panel case could be used for more than just protection and easy transportation, but I was. 

With the solar panel set up, it was time to connect it to the Delta Max Solar Generator. This gadget looked imposing, and weighed a ton, but was incredibly easy to use. All I had to do was connect the solar panel's power cable to a port on the Delta Max. The solar generator instantly recognized the solar panel and began charging. The Delta Max's screen showed its current charging rate (measured in watts), along with how many hours it would take to fully recharge the battery inside. This was extremely helpful because it let me know whether I had to move the solar panel around, or adjust its angle. It's common sense that a solar panel will be more effective when you move it away from shade cast by a tree or the side of a house; knowing that a half turn to the left can increase the panel's effectiveness by 15 percent is much less intuitive.

First Impressions of the EF ECOFLOW Delta Max

I tested the solar panel's efficiency in a couple of spots on the front lawn of a suburban home on a sunny day, and saw firsthand how much moving it around can make. In a slightly shaded area, EF ECOFLOW's solar panel was only transferring energy to the Delta Max at a rate of between 10 and 20 watts. It would have taken dozens of hours to charge it up at that rate. By moving it into a sunny spot, the solar panel was charging the Delta Max at a rate of 140 watts, and would recharge the solar generator in 11 hours. Yes, that's still a long time, but the difference was remarkable. It should be said that you can charge the Delta Max by plugging it into an outlet — which admittedly takes less time because there's no variability in how much energy it's absorbing — so you're not out of luck if weather is crummy. 

The bundle I was sent for review had a single solar panel, but you can hook two of them up to the Delta Max at one time. Under optimal conditions, you can charge the Delta Max at a rate of up to 440 watts. Based on my experience, that'd mean being able to fully recharge the Delta Max in just between five to six hours. Each solar panel costs $549, though, which makes its very expensive proposition. We hope that improvements in manufacturing processes lead to price cuts on solar panels over the next few years regardless of the manufacturer. EF ECOFLOW says you can use any solar panels that use the same "EcoFlow Solar Connectors," aka plugs that can connect to the ports found on the Delta Max.

Space and Charging Considerations

A persistent problem you may have when using a solar panel to charge the Delta Max is finding enough space to set it up. The solar panel requires several feet of clearance when it's unfolded, which makes it a no-go in crowded areas, including densely populated public campgrounds. If you have the luxury of a front or backyard that gets good sun coverage, or take trips to a private campground there's no doubt that EF ECOFLOW's bundle of a solar panel and the Delta Max can help you use renewable energy more easily, but space is an absolute necessity. It's worth noting that the EF ECOFLOW's solar panel is pretty compact when it's folded up. This is helpful for both at-home storage and for times when you want to pack the solar panel up in your car. The solar panel's protective case has a handle, which makes it easy to carry around, too.

At first glance, EF ECOFLOW's Delta Max may look like the more boring part of the company's sustainability tech bundle because it can be written off as a huge battery pack. That's true to some extent, but the Delta Max is so well constructed and thoughtfully designed that it's worth recommending on its own. The 48-pound solar generator has a capacity of 2016 WH (watt Hours) and can output up to 2,400 watts of electricity at a time. EF ECOFLOW says the Delta Max can be fully recharged in about 65 minutes when connected to an outlet using the included AC adapter, though I stuck to solar charging during my tests. 

The Delta Max's high battery capacity and generous number of outputs makes it a natural choice for campers, or anyone who wants to be prepared to power their essential electronics in the event of a blackout. The frontside of the Delta Max features two 100-watt USB-C PD (Power Delivery) ports and four USB-A ports, two of which support fast charging speeds.  These ports are perfect for charging smartphones, tablets, game consoles, headphones, Bluetooth speakers, and all manner of other portable electronic devices. I connected a handful of gadgets from these categories to the Delta Max at once and all of them started charging immediately.

The Delta Max's front side also houses its LED color display, which shows how much power it's outputting in real time, and how many hours it can run before running out of juice. This is extremely helpful information because it'll help you moderate your energy use to avoid dealing with a dead battery. The Delta Max's screen also includes the traditional battery percentage number, which ticks down as you use it. You can check the solar generator's energy levels by staring at the screen, but you also have the option to monitor that information on the go using the EcoFlow mobile app. The app is entirely optional, and is not required to use the Delta Max. That said, it was helpful to keep tabs on its battery levels when I wasn't in the same room.

Using this feature requires you to create an EcoFlow account, and keep the Delta Max in an area where it can maintain a strong connection to an active WiFi connection. The app walks you through the process of how to connect the power generator to your phone, and eventually the internet, and is pretty user-friendly. Overall, I'm happy that the app exists, but glad it's not a requirement. 

On the back of the Delta Max, you'll find six AC outlets, a car power outlet, and two DC outlets. The car power outlet was of particular interest to me because one of the gadgets I rely on regularly is a tire inflator that's powered using that connector. Sure enough, the inflator sprang to life when I plugged it in and hit its power button. I'll always keep the tire inflator in my car, but it's good to know that I can rely on the Delta Max if I decide to inflate bike tires indoors. While the solar generator's car power outlet served one of my niche needs, its AC plugs are the real stars of the show. These ports allow you to use the Delta Max to power appliances like coffee makers, microwaves, and toasters, or high-powered electronics like big-screen TVs and party speakers.

Battery Power

My big battery test was using the Delta Max to charge an electric bicycle. In one hour, the solar generator charged the bike's battery by approximately 30 percent (its screen doesn't show battery percentages) while draining the Delta Max by only 7 percent. During that test, the Delta Max displayed that it was outputting power at a rate of approximately 120 watts, and could sustain that level of energy output for 14 hours. That means I could fully recharge the bike several times before having to top up the Delta Max. Since I used solar energy to charge it, my entire e-bike charging system used 100 percent renewable energy. It may seem a little idealistic considering the price and space requirements of EF ECOFLOW's bundle, but it was the highlight of my testing time with these gadgets. 

EF ECOFLOW says the Delta Max should last 800 recharge cycles, which may seem alarmingly low at first, but makes sense if you take a step back. This isn't an inexpensive battery pack you'll drain and recharge after a day of casual use, it's designed for extreme conditions like camping or multi-day blackouts. You may only recharge the Delta Max once per month, in which case the solar generator would last 66 years without needing to be replaced. If you charged it once a week, the Delta Max could continue to hold a charge for 15 years. You may also be worried about the Delta Max slowly losing its charge while sitting on a shelf between charges, but I didn't find that to be the case. The solar generator kept the exact level of charge after two weeks of not being used. You should check the Delta Max once every couple of months to make sure it hasn't lost a charge, but I wouldn't worry too much about it.

Final Thoughts on the EF ECOFLOW Delta Max

Three final observations about the Delta Max that stood out to me. First, its weight didn't turn out to be much of an issue because of the handles on either side of its top piece, which made it easy to move around. The solar generator still weighs close to 50 pounds, but the handles helped a lot. Second, you need to press a button on the front and back of the Delta Max to turn on its two sets of ports. This prevents the solar generator from supplying energy to both sets of ports when only one set is required, saving power. Third, the Delta Max's screen will show the ports that are currently being used by displaying a small picture of it beneath the battery indicator. The utility of these three design details didn't occur to me at the time, but stuck out upon reflection. 

The price of EF ECOFLOW's bundle is pretty steep, but fully worthwhile when you consider how well both its solar panel and solar generator perform. The fact that the Delta Max has the flexibility to be charged independently of the solar panel, or with multiple panels connected, makes it an especially compelling tool to use during parking lot tailgates, beach parties, and other gatherings. The age of consumer-level solar charging equipment has begun, and if the gear I've tested from EF ECOFLOW is any indication, it couldn't come quickly enough.

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This post was created by a non-news editorial team at Recurrent Media, Futurism’s owner. Futurism may receive a portion of sales on products linked within this post.

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