Renogy E.Flex 21 Review – Portable Solar USB Charger

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Product: Renogy E.Flex 21 Portable Solar Panel USB Charger
Price: $79.99
Dimensions Folded: 11.0 x 7.3 x 1.2 inch/280 x 185 x 30 mm
Dimensions Unfolded: 23.0 x 11.0 x 0.8 inch/585 x 280 x 20 mm
Weight: 28.9 oz / 820 g
Warranty:
Solar Panel: 25-year power output
5 Year 95% efficiency
10 year 90% efficiency
25 year 80% efficiency
5 year workmanship and materials
Accessories: 12 month material

If you are in a hurry I have provided a quick jump menu;

E.Flex 21 portable solar panel charger review

20000 mAh power bank

What’s good and what’s not so good about the E.Flex 21

E.Flex 21 Vs the Anker PowerPort 21

Other E.Flex products in the range

Renogy E.Flex 21 Portable Solar Panel USB Charger Review

I will be taking a good look at the E.flex 21 watt portable solar charger. Matching it with the Renogy 20000 mAh power bank.  Pitting it against the Anker 21 watt portable solar panel. Looking at the good and not so good points. And flicking through other E.Flex products in the range.

A bit about Renogy

Renogy was started by students at Louisiana State University. Renogy LLC was organized in 2010 and in 2013 they launched their online store. By 2013 they incorporated as the RNG Group Inc. In 2016, Renogy won two bronze-level Golden Bridge Awards. One of them for best product of the year with the Lycan solar power station.

Today Renogy produces a wide range of solar products and solutions. These include the recreational vehicles, home, truck, marine and commercial sectors. With solar power becoming more popular and more widely used as an alternative source of power generation. Their product range and technological innovations are bound to expand. To meet the challenges of global warming and reducing the world’s carbon footprint.

Renogy products are well-made and respected. The company has a reputation for quality workmanship, reliability, durability and customer service. E.Flex portable solar power kits  are engineered to fit into these high standards. That’s enough about the company, it’s onto the review proper.

What Is The E. Flex 21 Watt  Portable Solar Panel USB Charger?

Construction

The E.Flex portable is made from three folded 7 watt solar panels. These are molded together within a nylon carcass, making it a soft fold-up panel. Then wired to a junction box with 2 USB ports. These are housed in a pocket to help protect them from knocks and the elements.

It has 5 cloth hooks so it can be hung using carabiners. And is completed with a kickstand. The portable solar panel folds down to about the size of a quality magazine. The E.Flex is a solar charger and doesn’t store a charge. A power bank is required to be able to do that. 

Specs

Solar Cell	Unknown
Module Type	3 x 7 Watt
Wattage	21w
Efficiency	22% to 25%
Dimensions Folded	11.0 x 7.3 x 1.2 inch/280 x 185 x 30 mm
Dimensions Unfolded	23.0 x 11.0 x 0.8 inch/585 x 280 x 20 mm
Weight	28.9 oz / 820 g
USB Output	2 x 5V/2.4A max
Optimum Operating Voltage	6V
Optimum Operating Current	3,5A
Open Circuit Voltage	7.2V
Optimum Operating Current	3.5A

Efficiency

Unusually Renogy are not saying the type of solar cell that is incorporated into the solar panel. They do however say that the e.Flex 21 has an efficiency rating of up to 22% to 25%. But remember these results will have been achieved in lab conditions. 

I would say that to achieve the best results. Standing the solar panel up on its kickstand will collect the greatest amount of sunlight. If you are going to attach it to your pack using the carabiners. I would make sure the sun was behind you.

Ports

The E.Flex 21 has 2 x 5V/2A USB ports housed in a small controller unit. Which incorporates the latest ISolar technology. It has a LED indicator which will flash. If it has been shut off due to overcurrent or short circuit.

ISolar technology

The incorporated ISolar technology is designed to provide;

• Detection of an attached device to deliver the correct charge for that make/model
• The fastest possible charging speeds
• Auto reconnect if charging is interrupted by cloud or shade
• Protect your device from overheating
• Reconnection after charging disruption
• Over current and short circuit protection

Tip; To achieve the fastest possible charging speeds. Remember to turn off your devices bluetooth and wi-fi etc … 

Remember; The ports are standard 5V/2A USB and not fast charging ports. They will charge your device just fine.  But don’t be expecting lightning speeds this is a small 21w solar panel. Not a 100 or 200w panel. And is meant for providing charging back up when off-grid.

Durable

Because it is constructed of nylon the E.Flex 21 is very durable. Knocks bumps and the odd accidental drop will do little damage to it. It is waterproof but remember the junction box isn’t. This is where the USB’s are housed and care needs to be taken around liquids. 

 It will probably survive liquids accidentally spilled on it. But as a precaution if it starts raining, stow it away. Do not leave it out overnight as it might rain.

Portability

One of the biggest benefits of the charger is its portability. Because it is so small and light it will comfortably fit into any pack or car. Fantastic for charging devices on a day out at the beach, a lake or in the forest. All you have to do is stand it up and let the sun and solar panel do its work. You can even use it if you travel around a lot for work. No more being caught out with a low battery. When the boss calls to find out how things are going

Reliability

If you are using it for hiking, cycling or backpacking. You will have few problems fitting it into your pack. Because it folds down to about the size of a magazine. Weight is always a concern but at just  28.9 oz / 820 g. It will not take up too much of your weight allocation making it easy to carry around.

What you really want to know is; Will the solar panel be reliable? It will be as long as you remember it’s limitations. As a 21w portable solar panel it is probably best used for topping off devices or power banks. 

I wouldn’t allow my device’s battery to deplete below 70% without topping it off.  If deeper charging is required for example 50%. I would work on 15% + charge per hour in full sunlight. That means 3.5 hours of exposure to bring your device to full charge Cloudy conditions will reduce the percentage per hour.

What can the E.Flex 21 charge?

• Smartphones
• Android
• Apple (original cable cable required)
• Cameras
• Small USB devices like a fan
• Power Banks

Charging a power bank instead of a device directly. Would enable you to charge a tablet. 

How can I use the E.Flex 21?

The portable solar panel can be used for various outdoor activities such as;

• Days out
• Trekking
• Hiking
• Camping
• Picnics
• Fishing
• Boating
• Climbing
• Backpacking
• Cycling

What’s in the box

1 x Renogy E.Flex 21 Portable Solar panel USB Charger
1 x 23.6inch/60cm Micro USB Cable
1 x USB-A to USB-C Cable
2 x Carabiners

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Power Banks

Most solar chargers have a limitation in the fact that under certain conditions like a cloudy day. If the cloud prevents charging whilst your device (e.g a smartphone). Is connected to the solar charger the battery can discharge back into the panel. 

This means your battery will lose charge. But if you charge a power bank instead of your device, this cannot happen. Because the power bank will prevent this by cutting the connection to the panel until sunlight returns. It will then automatically start charging again. 

The other advantage is that you can top up the power bank all day and charge your device at night. This is great for when you are out hiking or cycling for a couple of days or more. 

What Is The Renogy 20000mAh Power Bank?

This power bank is super light and super small and will charge any USB device. It has an on off switch and LEDs indicating levels of charge. Ideal to match up with the E.Flex 21 portable solar charger.

Specs

Capacity	20000mAh / 72Wh
Battery Chemistry	Lithium-Ion
Dimensions	2 x 2 x 4.05in / 5.1 x 5.1 x 10.3cm
Weight	11.55 oz / 327.5 g
Charge Cycles	Up to 1,000 times
Output Ports	3 x 5V/2.4A max
Input Port	5V / 2.4A max
Warranty	12 month material
Price	$39.99

In case you didn’t know what mAh means;
It is the battery capacity expressed as a milliampere of an ampere hour.

In case you didn’t know what watt-hour means:
It is the rate of energy the power bank will produce, to charge an electronic device per hour. You can find a technical explanation here (source: WhatIs.com), The higher the Wh, the more devices you can charge, (and how quickly)

Capacity

For such a small power bank the Renogy 20000mAh has a very large capacity. The lithium-ion battery will last up to 1,000 charge cycles. Which I have to say is pretty impressive.

Size and Weight 

The size and weight is ideal for any outdoor activity where space is tight. It will easily fit into a handbag. And you will hardly feel it’s 11.55 oz / 327.5 g in a pack. The combined weight with the E.Flex 21 is 2.53lbs/1.15kg. 

Output Ports

The three USB output ports can charge 3 electronic devices simultaneously. These include;

• Smartphones
• Cameras
• Tablets
• USB Enabled Laptops

Safety features

Short Circuit Protection	Cell Overvoltage Protection
Backflow Prevention	Output High-Voltage Protection
Automatic Cut Off Protection	Input High-Voltage Protection
Input Overcurrent Regulation	Output Overcurrent Regulation
Cell Overcurrent Protection	Automatic Current Matching
Anti-Static Protection	Voltage Boost Technology for Cable Drop Compensation

What’s in the box?

1 x Renogy 200000mAh Portable Charger
1 x 23.6in/60cm Micro USB Charging Cable
1 x Travel Pouch
1 x User Manual

Latest Price from Renogy

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What’s Good About The E.Flex21 Portable Solar panel USB Charger?

Efficiency

With an efficiency rating of 22% to 25% and Renogy’s ISolar technology incorporated. You should have little trouble charging your devices or power bank.

Reliability

The warranty for the E.Flex suggests Renogy are pretty confident about the product’s reliability. As long as you treat it as what it is; A 21w portable solar panel for back up use. I doubt it will disappoint when using it on the go.

Size

Your pack weight and the amount of things you can fit into it is always important. I think you will find that the E.Flex will fit quite snuggly in a pack. Without you having to compromise what you can carry with you.

What’s Not So Good About The E.Flex 21 Portable Solar panel USB Charger?

Not fully waterproof

The E.flex 21 is described as water resistant, not waterproof. As I mentioned earlier this is because of the USB housing. It is protected and enclosed within a pouch.that is closed using velcro. I think it will be ok in light rain but I would pack it away in heavy weather.

Unknown solar cell

I don’t know why Renogy hasn’t released which kind of solar cell the E.Flex uses. But the literature says the efficiency rating is high. I do not want to speculate with regard to this. So I suppose it needs to be taken at face value. 

Direct sunlight required

All solar panels perform best in direct sunlight. You need to remember this is only a 21w portable solar panel. The convenience of attaching to your pack to collect sunlight is great. But it will not be as efficient as when standing it up in direct sunlight. And if it is cloudy I wouldn’t be expecting miracles.

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What Other Products Are There In The E.Flex Range?

There are 3 other portable solar panels in the E.Flex range;

Specs	E.Flex 10	E.Flex 30	E.Flex 50
Power Wattage	10w	30w	50w
Solar Cell	Monocrystalline	Unknown	Monocrystalline
Efficiency	High Efficiency	Up to 22% – 25%	21% – 23%
Dimensions Folded	9.5 x 5.9 x 0.26 inch	11.8 x  6.3 inch/30 x 16 cm	19.9 × 16.1 × 0.8inch/506 × 408 × 20mm
Dimensions Unfolded	9.5 x 12.2 x 0.13inch	25.4 x 11.8 inch / 64.5 x 30 cm	32.5 × 19.9 × 0.2inch/826 × 506 × 5mm
Weight	13oz	1.6 lbs /716 g	5.25lbs/2.38kg
USB Port	1 x 5V/1.92A Peak	3 x 5V/2A	1 x 5V/3A and 1 x 5V/2.4A
Warranty Panels		25 Year Output 5 year Material and Workmanship
Warranty Accessories	12 Months	12 months	12 months
Price	$49.99	$109.99	$139.99

See the Renogy E.Flex range here

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Renogy E.Flex 21 Vs The Anker 21w PowerPort

	Renogy E.Flex 21	Anker 21w PowerPort
Solar Cell	Unknown	Monocrystalline (SunPower)
Module Type	3 x 7 Watt	3 x 7 Watt
Wattage	21w	21w
Efficiency	22% to 25%	21.5% to 23%
Dimensions Folded	11.0 x 7.3 x 1.2 inch/280 x 185 x 30 mm	11.1 x 6.3inch
Dimensions Unfolded	23.0 x 11.0 x 0.8 inch/585 x 280 x 20 mm	26.4 x 11inch
Weight	28.9 oz / 820g	17.6oz/499g
USB Output	2 x 5V/2.4A max	2 x 5V/2.4A max
Warranty	Solar Panel: 25-year power output5 Year 95% efficiency 10 year 90% efficiency25 year 80% efficiency5 year workmanship and materials Accessories: 12 month material	18 Months
Price	$79.99	$69.99

These are both 21w three fold 7 watt portable solar panels. The Renogy is claiming a higher efficiency rating than the Anker. 

Size and weight

The PowerPort is significantly lighter than the E.Flex and slightly smaller. However the reduced surface area will affect sunlight collection over the E.Flex.

Ports

Both have two 5V/2.4A  USB ports built into a protective pouch. And incorporate advanced technologies for charge management. 

Warranty and Price

The Renogy has a far superior warranty but the Anker is $10.00 cheaper. But Renogy has frequent offers on their products.

You can look at a full Anker PowerPort review here

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Solar Power Has Some Limitations

Solar power is fantastic, because it provides an environmentally friendly energy source. Let’s be honest. Without solar panels the world would be relying on smelly, noisy gasoline generators. You just need to be aware of a few things.

When it is overcast, the PV cells will receive less light. Reducing the rate of charge, meaning it will take longer to charge your batteries. This isn’t a major problem. Until full sunlight returns, limit the number of devices you are planning to power or charge .

Shade will stop charging altogether. Keep an eye out for this now and again and move the E.Flex 21 portable solar panel back into the sunlight if necessary. This is important if you are near an overhang or obstruction such as in and around a forest. You will need to check for shade more often.

Is The Renogy E.Flex 21 Any Good?

Renogy is well known for producing quality solar products and I can’t see the E.Flex being any different. As a solution for a small lightweight portable solar panel to charge phones. It fits the bill quite nicely to generate electricity out in the wilderness. 

It might also be handy at home if there is a power cut or extended outage. It would be nice to be able to charge your phone. Or a fan or a flashlight under emergency circumstances. It is always best to be prepared 

I hope you enjoyed this review and have found it helpful. If you have any questions about the Renogy E.Flex 21 Portable Solar Panel. Or want to leave your own personal review, please feel free to leave a comment below.