SUNNYBAG Portable Solar Panels - Tested and Reviewed

Every time I think hiking gear is as good as it can get, out comes another round of innovation that addresses weaknesses we’ve tolerated for a long time. Today we’re going to look at a couple of very promising solar panels for hiking and camping. 

The company, SUNNYBAG, sent me a couple of solar panels to test and review. SUNNYBAG is an Austrian company, but they distribute world-wide. 

The rules of engagement with this review was that it was to be completely independent – no scripts, no direction, just me doing my thing, my own way – what you’ve all come to expect from me. 

They sent me two different panels: the LEAF MINI and the SUNBOOSTER 21. 

Both of these are of a size and weight that could be used for hiking or camping. But, depending on your power needs or your desired carry weight, you might choose one over the other.

Weight, Output Power, and Compatible Devices

The LEAF MINI has one USB-A output port; the panel is small; it weighs 5.7 oz; and the power output capability is 5 Watts. 

The SUNBOOSTER 21 has two USB-A output ports; it's larger than the LEAF MINI; it weighs 24 oz; and the output power capability is 21 Watts. But, the power output capability is split between the two ports. The most realized on any one port is 10.5 watts. 

Both of these panels can charge just about any device a hiker might have with them: phone, battery bank, GPS device, headlamps, air pumps, watches, camera or drone batteries, etc. 

Keep in mind, however, that every device, has specific minimum power level requirements for charging; some won’t charge until the current level exceeds 500ma, for instance. 

And each device has specific and sometimes limiting circuitry that manages charging. For instance, some devices will reduce charging to a “trickle charge” when it reaches 85%; some won’t charge past 85% as a measure to help preserve the life of the battery. So, like I always advise: be familiar with your devices and test all your gear before you head out into the wild. 

But generally speaking, these panels should work fine for whatever you are taking with you on your hikes.

LED Indicator

Each of these panels has an LED indicator which will show a different color depending on the output current when under load; that is, when a device is connected to the panel. 

• A red light indicates the output current is between 0 and 500mA (milliamps). If you are charging a 5v (volt) device, that’s up to 2.5W (watts) of power output. The formula for power (wattage) is voltage times current (in amps). You may find that if the indicator is red, it may not be enough to charge your device. Again, be familiar with your device requirements.
• A green light indicates the output current is up to 800mA; at 5v = 4W.
• A blue light indicates the output amperage is at least 800mA but up to the maximum output. For the SUNBOOSTER , rated for 2.1A at 5v = 10.5 W. For the LEAF MINI, rated for 1A at 5v = 5W

Obviously, the most desired colors are green and blue. Again, this indicator requires that a device be connected to the panel. If the panel is exposed to light, the indicator will be red until a device is connected.

These LED lights are a great feature. It lets you know if you have the panel positioned correctly and it gives you a rough idea about power output and, consequently, charge times. Many panels I’ve tested don’t have this feature. Also worth noting is that the associated circuitry does not notably consume any power or reduce the power available for your charging. So, it’s a great feature with no downside. 

Things that impact power output of any solar panel

Just to make everyone aware of how these things work, I want to review a few things that may impact the power output of any portable solar panel. Here are six things worth mentioning:

• The angle to the sun. When the panel is at 90 degrees to the sun it will be most effective. Aim the surface of your panel directly at the sun to get the most out of it.
• The level of sun intensity and exposure. These panels work best when you have full and unobstructed sun exposure. That is, no clouds or obstructions of any kind, like smoke or haze, and no amount of shade. Also note that early morning and late day sun intensity is not as much as mid-day. So in those times, performance will be less.
• The health of the battery being charged. If you have a old/worn out battery, it may not charge like a new one
• The air temperature. Batteries and solar panels behave differently at various temperatures. You should expect diminished performance at very high and very low temps.
• The rating of the cable used. Check to make sure your cable is rated for at least 2 amps (or at least 11 Watts) to get the most out of these panels.
• The control circuitry in the charging device. Some devices will limit the charging current to prevent overheating. This might appear to be lower performance, but it’s really just a safety feature in the device.

So, consider that some factors or conditions may need to be addressed to get optimal performance from your portable solar panel charging system. 

Durability 

These panels have a very durable scratch resistant coating, making the panel actually waterproof. Other manufacturers will say their panels have water repellent qualities. These are actually waterproof. 

There is one caveat to that – it’s the USB connector, which can be susceptible to water exposure because its an open, unsealed connector. I asked SUNNYBAG about this, they said the fix is already in production. The newest design will have covers on the connectors. But some of the stock in the U.S. may still be the version without the connector covers. 

If you get one without connector covers, you may consider spending another $5 on Amazon, where I got mine. 

But aside from these connector ends, these panels have very durable construction. 

It is gut wrenching to be deep in the wilderness with an inoperative power source because it couldn't handle the conditions. You want something durable and reliable. These definitely meet the challenge. To date, these are the most durable ones I’ve tested. So, thumbs up from me.

Packability 

The LEAF MINI is a single small panel. It doesn't fold, which is fine. It’s small enough to fit easily on the outside or inside of your pack .

The SUNBOOSTER has three panels that fold together. It’s bigger than the LEAF MINI, but it’s still packable. Of course, the size of the panel is directly proportional to the power output. So, it’s bigger, but you get more. 

These panels are rigid. But their rigidity contributes to their durability. 

If you are putting these inside your pack, just understand that they won't bend and mold like a sack of cloths will. That's not necessarily a negative, but just be aware. 

Actually, because the panels are waterproof, you could just leave them on the outside of your pack, with a covered USB connector or a device connected. 

The units have sturdy grommets on all four corners. These provide a way for you to connect them to your backpack. Each backpack has different connection points. So, you’ll have to rig yours up to work for you. You may consider using elastic shock cord and bungee cord hooks to help reduce stress on the connection points, both on your pack and the panel. 

Quality Control 

SUNNYBAG guarantees individual unit testing, in writing, under signature. The testing shows that each unit will have at least a 22.4% conversion efficiency, which is a good power conversion rating for a portable solar panel. 

They also test power output over a range of voltages and current demands. And they provide a graph of their testing results. 

I did a lot of electronic systems quality control and testing in my time. I can tell you that only those who are serious about quality will give you the actual measurements and attest to their findings under signature. So, to me, this is exceptional. Instills confidence. Very good. 

Warranty 

SUNNYBAG has a 30 day return policy and 2 year warranty that you can extend to 5 years by simply registering your purchase with them on their web site. 

Auto restart support  

Some devices have a minimum threshold of 500ma for charging. And some of those devices will have an auto charging restart feature to help manage this when the power input is fluctuating above and below the minimum threshold. 

Here’s how this works: 

Let's say you have good sunlight and you see the power indicator is green or blue and your device is charging - but then some clouds cover the sun and the indicator turns red and your device stops charging. 

Then the clouds move away and the indicator turns green or blue again. 

Without support for charging auto restart you may need to unplug your device and plug it in again for it to resume charging. 

But if your device has charging auto restart, your device will automatically restart the charging. 

Some devices don't have this feature. My Android does not have this feature, so I need to reconnect every time the LED indicator dropped to red and then back to green. However, my Garmin device does have this feature. I was watching it turn on and off – cycling through restarts when the LED indicator was on.

I understand that iOS devices do have this feature. So, this should work great for Apple devices.

Testing 

I took both of these out in the back yard just to run through a few tests before I take them out on a hike. 

• I used my meter to measure actual output under various conditions. 
• I tested in the early morning and near mid-day.
• I tested with some cloud cover and with full sun exposure.
• I used a lower rated cable. Then used a higher rated cable. 
• I tested on different devices – my GPS unit, phone, and battery bank – since these are the primary devices I would typically take with me on a backpacking trip. 

You can see the actual testing on this YouTube Video.

Testing Results

The bottom line in my testing is that it worked as expected. But, here are a few things you need to know.

If you are going into this thinking that you will always get the max amount of power delivered to your device every time you set this up, you’ll need to adjust that expectation because it’s not realistic. Here’s why:

The Difference Between Specs and Real-World.  The first thing is that the advertised specs for these units were determined in a lab, in a very controlled environment. When you get these out on the trail in real-world situations, there are many more environmental variables brought into the equation: fluctuating sun intensity and temperatures, positioning of the panel against a constantly moving sun across the sky, if you have it strapped to your backpack you are constantly changing the alignment of the panel to the sun, and there are other variables, like I reviewed earlier. But just know that the lab environment is “ideal”; rarely do we get an ideal situation in the field. 

And keep in mind that the specs are a statement of capability of the electronics, not a test in the actual-use environment. So, the specs and advertised capabilities are technically correct but only from the perspective of the lab environment. In the field it will be different for many reasons. 

Every Device Demands a Different Power Level. You saw from my testing that different devices will draw different amperage levels, which means the power to each device will be different. A powerbank will draw more current than a cell phone, for instance, and therefore receive more power from the solar panel.

And based on that finding, we can say that you’ll get more efficient use out of a solar panel while backpacking if you use it to charge a powerbank and then use your powerbank to later charge your phone and other devices. This is my normal use of a solar panel when I’m backpacking. I’ll first fully charge my powerbank, before charging any other device.

The Point of Testing. The point of my testing was to verify that the unit is actually and reasonably charging my devices. And, in fact, they did; and in some cases actually exceeding the specs. 

By the way. On the back of the packaging and maybe on the website you’ll see charts that seem to indicate charge times for different kinds of devices. While this may be a reasonable guide, don’t take it as absolute. Again, there are too many variables that can change charge times. 

Final Summary

There are a lot of portable solar panels on the market... hundreds... maybe more. And that kind of market saturation may be what lead you to this article and my video. I can tell you that after testing many portable solar panels, that this one checks all the important boxes for me and then some. 

It’s waterproof, durable, the LED power level indicator is a great feature, the electronics test good; they are portable; light weight, reasonably priced, etc. 

I’ll be using these on hikes where I’ll have a lot of sun exposure and power needs (which I usually do). 

The LEAF MINI will be great for longer multi-week hikes where I need to reduce my base weight. It’s durable, reliable, and lighter than batterybank. 

The SUNBOOSTER 21 will be nice for shorter hikes or base-camp scenarios where my base weight is less of a concern and I want the luxury of more power. 

And a brief comment about the support. I’m always asking a bunch of clarifying questions and getting more detailed information about the products when I do these things. I can actually be a little annoying. Why? Because I have the right kind of background to know what questions to ask, and you need to know what you’re spending your hard-earned money on. 

Also, it’s worth noting that SUNNYBAG has been great at quickly getting back to me and it was good to hear that they had already addressed the one issue I had with the product (the USB connector cover). This demonstrates to me that they are innovators, looking for ways to improve, and they are open to feedback. Those are all great things. 

Again, both panels are great are choices, each for a little different situation.

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