How Does the Inergy Flex Solar Generator Stack Up Against the Rest?

Inergy Flex 1500Inergy is a company that has made a lot of waves in the solar industry. When they came out with the Kodiak, it blew the competition out of the water. The only thing close was the Goal Zero Yeti 1250, but it really wasn’t a competition. The Kodiak was powerful and light, being one of the first companies to use lithium-ion batteries. After the Kodiak, Inergy released the Apex. It was completely overhyped and unfortunately it under-delivered. You can read my review about it here.

The newest model is the Flex 1500 Power Station. It has not hit the market yet, so this review will just be looking over the listed specs and features. When it hits the market, I will do a more thorough review and see if it actually performs according to what they say. People have been asking me how it compares to my favorite and most recommended solar generator, the Point Zero Titan. It shares some very similar features, but can it compete with the best?

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Battery Capacity

Battery capacity determines how long your system can run electronics before it needs to be recharged. The bigger capacity, the longer it will last. More battery capacity comes at a cost, both financially and in terms of weight. Batteries are the heaviest component of a solar generator system. When I am looking at purchasing a solar generator, I look at what I need it to do, and then buy the generator that meets my needs.

Inergy Flex SpecsThe Flex 1500 uses a 1069Wh 12V Lithium-ion battery. Most companies use a model number equivalent to the battery capacity, but in this case, it’s called the 1500 because of the inverter size. Like the previous models, they’ve stayed just above that 1000Wh mark. I’m curious why they haven’t made it bigger than that. A lot of new companies are pushing between 1500-3000Wh, and in my opinion that just makes a much more capable system.

I’m curious to see during testing to see how much battery capacity it actually has. When electricity is converted from DC power (solar) to AC power, there is always loss due to inefficiencies. A lot of companies advertise the nominal size of the battery, not the actual. The only generator I know of that I can actually use the full listed amount of the battery is the Titan which has 2000wh of usable battery capacity.

The Flex 1500 battery is detachable from the rest of the system. This is a really nice feature because when the battery wears out, I can just buy a replacement battery and I don’t have to send the whole unit back to the manufacturer for them to put a new battery in. I can also have a backup battery on hand to switch out with the old one when it wears out.

Point Zero was the company that came up with the detachable battery idea. How does their battery compare? The Titan uses a 2000Wh Lithium-ion battery, and you can actually use all 2000Wh. That is because the battery is actually larger than the number advertised, so when they say 2000Wh that is actually what I am going to get. So one Titan battery is equal to two Flex batteries.



Flex With Expanded BatteriesWhat really makes the detachable battery cool is that I can add multiple batteries to each other to expand my overall battery capacity. Now, I’m not going to sugar coat it here. It appears Inergy has blatantly copied the Point Zero Titan battery stacking design. While it is unfortunate to see another company copy another company’s design, it is a very well thought out system and I love how it works. Imitation is the highest form of flattery.

By expanding my battery capacity, I can lengthen the time I can operate my electrical appliances before I have to recharge. My biggest concern is always looking at if I have enough battery to run my appliances through the night until I have sunlight to recharge those batteries. Having the ability to have more or less batteries for any given application is a nice feature, and one I hope more companies will incorporate in the future.

The Flex 1500 and the Titan are essentially equal in this department. But I have to give the edge to Titan for being the ones who actually came up with the idea.



The weight and portability of the solar generator is an important consideration depending on application. I’m not that concerned about the portability of an off-grid cabin solar generator setup because once it is setup, it isn’t moving. For my RV, camping, and road trip needs, I want something that I can easily load into my rig and not break my back doing so.

The overall weight of the Flex 1500 is 30 pounds, and if you detach the battery both halves way 14 pounds and 16 pounds. That is very light and makes it very easy to move around. Its footprint is 14”x9”x8” so it doesn’t take up much floor space either.

The Titan is about double this number. 66 pounds for the overall system, 31 pounds and 35 pounds if you split them up. Double the battery size, double the weight. 30 pounds give or take is still easily maneuverable, so they both are great in this area.

That means that the Titan has double the weight, as well as double the inverter capacity and double the battery capacity.

One really nice feature of the Inergy Flex 1500 batteries is that you don’t have to calibrate them to be the same voltage before stacking them together. Or at least that’s what they say. You can stack the batteries together safely even if they’re at different voltages. The Titan batteries need to be within .5v of each other when connecting them. However, I only have to do that once with the Titan since I’m using multiple batteries and those batteries always stay together, they never go out of balance from each other after the initial setup.

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Charge Speed

Flex Charge SpeedCharge speed is important to look at, because if I can’t recharge my battery all the way in one day, then I don’t have a system that can operate day to day. It’s like if I was driving my car daily but I couldn’t afford to fill up the gas tank all the way. Eventually, it will run empty and I’ll be stranded.

I want a solar system that can recharge daily so that I go into the evening with a full battery, meaning I don’t have to worry about my appliances turning off leaving me in the dark. A day in solar terms is the window of optimal sunlight, typically 5-6 hours.

The Flex 1500 can handle 600W of solar input, meaning that it could recharge a battery in a little less than two hours, well under the 5-6 hour window. If I added a second battery, I could still charge up to 2000Wh+ in around 4 hours. I like to leave a little cushion room because conditions will not always be perfect. Clouds, shade, smoke, and other factors can make for imperfect conditions and it might take longer.

I take the “600w charge speed” with a grain of salt because they had said that about the Kodiak as well as the Apex and it wasn’t actually 600w of solar input that it could handle. In fact, many customers fried their Kodiaks trying to connect 600w of solar panels because the charge port could really only handle 30 amps max. And when 6 panels are connected in parallel together the amperage can reach around 36 amps. That caused many people dangerous situations with their Kodiaks melting wires and components.

I can also charge the Flex 1500 by way of AC wall outlet or with a car charger. Using the wall charger, it can charge in about 11 hours. Not the fastest, but not the slowest either. The car charger can charge in about the same time. Car charging is very nice when road-tripping and RVing to be able to charge between destinations.

The Titan has a max solar input of 1000W, almost twice as much as the Flex 1500. And if I add a battery, I can increase my solar input by another 1000W. To be fair, the Flex 1500 has a MPPT Supercharger that allows me to charge up to 1200 watts, but it’s an extra add on that costs $500. No add on needed for the Titan. The Titan is really just double that of the Flex 1500. Battery is twice as big, and the solar input is twice as much.

The nice feature of the Flex 1500 is that you can add as many MPPT Superchargers as you’d like. Essentially, for every battery you can add another MPPT Supercharger if you’d like. It does get very pricey at that point but then the charge times from solar stay very low.

The Titan has a max solar input of 2000w but I have found that to be plenty even for my off-grid cabin that runs 100% year-round with the Titan.


Life Cycle

Solar generators have made huge improvements in capability since going to Lithium-ion batteries over lead acid batteries. Lithium-ion offers many benefits, one of which is the increased lifespan of the battery. This is referred to as life cycles, and it’s the number of times a battery can go from 100% to 0% and then back to 100%. After a certain number of life cycles, the battery will start to lose its overall capacity, usually down to about 80%. I want to buy something that has a high number of life cycles so that I know I can rely on my system for years to come.

Inergy Flex CookingIt was tricky to find the life cycles of the Flex 1500. It isn’t listed in the specs or features of the main listing. Under the FAQs they say, “The cycle life of your battery is totally dependent on how you use it. Your Flex Battery could last anywhere from 400 cycles up to 2,000 cycles or 10 years if you use it to run moderate loads and take good care of it.” I’m not sure what that means. Everybody else posts an actual number of life cycles I can expect from their system.

The Titan actually is listed as having 2000 Life Cycles. The way they get this high number is by oversizing the battery, but then limiting how much of it I can actually use. This means I never actually drain the battery to 0% which means the battery lasts longer. Very smart move by Point Zero.

Number of plugin ports

The Flex 1500 has a good amount of ports and outlets. 6 110/120V wall outlet plugs, 2 DC ports, 2 USB A, and 2 USB C ports. My only complaint would be that it seems like the wall outlet plugs are too close together. If I was using a power cord with the box on the end, it would most likely make the outlets on either side unusable.

The Titan also has 6 110/120V wall outlet plugs, and it has 4 DC ports which gives me the option of either DC power or I can use converters for USB type plugs. The spacing on the wall outlet plugs is much better in my opinion and there is no overlap with a box style power cord.

I should also add here that the Titan has a switch to run either AC power or DC power only. If I only needed DC power, I can run it more efficiently by flipping the DC power only switch. The Flex 1500 has a whole different power station dedicated to DC power only. I much prefer the simpleness of a switch versus a whole new system.

Inverter Size

The inverter determines how much power I can draw from the battery, which determines what kind of equipment I can use. The bigger the inverter, the bigger the equipment. The Flex 1500 has a 1500W continuous Pure Sine Wave inverter with a 3000W surge capacity.

The previous model, the Apex, also had a 1500W inverter but the battery could only output around 850Wh. This made it rather pointless to have an inverter that big if it is limited by the battery. Inergy claims the Flex 1500 doesn’t have this issue as it can run 1500W continuously from 100% of the battery down to 20%.

The Titan on the other hand, just like the battery and solar input, is twice as big. 3000W continuous Pure Sine Wave inverter with a 6000W surge capacity. This allows me to run power equipment like chop saws, welders, etc. Just like in my vehicles, I prefer the power of a V8. The Titan has been tested and can actually draw 3000W continuously until the battery is at 0%. That is amazing.

RV Connectivity

A dedicated RV 30-amp style plug allows me to plug the solar generator in to the RV and power everything, without having to run power cords everywhere. It is a really nice feature that I like to have. The Flex 1500 does not have this feature. Their previous models, the Kodiak and the Apex, did have one. It wasn’t great, because even though it was a 30-amp style plug it could only pull 12.5 amps.

The Titan does have a dedicated RV 30-amp style plug that can pull 25 amps. Plenty of power to run my RV, and because of the size of the inverter could even run an AC unit.

Customer Support and Warranty

I want to know that I’ll be taken care of when I buy an expensive piece of equipment. I want to be able to call a company if I have issues or questions and talk to an actual person instead of hearing a long list of menu options and getting the runaround.

Inergy Flex UnitInergy doesn’t have a great track record of customer service. A quick look at Amazon reviews and you can see the issues people have had. That makes me really nervous about spending my hard-earned money. But they do offer a two-year warranty on the Flex 1500. They are offering a 10-year warranty on their batteries if you buy their system at a Pre-sale price.

It could’ve been an anomaly but when I called Inergy to ask more questions about the Flex 1500 I was on hold for 37mins. Then I got hung up on. I called again because I thought there’s no way they’d just hang up on me. I waited 42mins and then got hung up on. Needless to say, I was not happy at all.

For the Titan it is very easy to get answers. Calling 800-489-0552 gets me directly to a customer service agent. Sometimes waiting in the queue happens because the phone number gets busy at times, but they always call back.

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Pricing and Final Thoughts

The Titan without panels is $2,995. I’ve already shown how it doubles the specs of the Flex 1500. If I add another battery and the MPPT Supercharger to the Flex to match the battery size and solar input specs of the Titan, it would cost $2,950 for standard pricing and $2,650 presale pricing. A difference of $45 and I get an inverter that is twice as powerful and a battery with 4x the life cycle.

Taking it a step further, let’s say I add another battery to the Titan. I would have 4000Wh battery capacity for $4,390. To get that kind of capacity with the Flex 1500 I’d be looking at 3 additional batteries and 3 additional MPPT Superchargers, which would equal $5,800. $1400 more than the Titan, and the Titan still outperforms and has more features.

That is why I highly recommend the Point Zero Titan over the Inergy Flex 1500. It beats it in every category and at a better price point. Buy with confidence!

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