The BigBlue 28W Foldable Solar Charger is our best solar charger with digital ammeter pick, and it scored 88 out of 100 in our testing.
The most reliable small USB solar charger here, so long as you accept it tops out near 20W of real USB output, not the 28W on the label.
A four-panel fabric folder with a built-in ammeter so you can angle it until the current reading peaks, which is why it stays ahead of a phone's drain on the trail.
Here's the deal:
We tested it head to head against the other top portable solar panels & chargers, and below we break down how it did on Value for Money, Charge Interruption Recovery, Charging Speed, Multiple Device Charging Speed, Durability, Weight & Portability, where it falls short, and whether it is worth your money.
Table of Contents
- Best Solar Charger with Digital Ammeter
- Our Verdict: BigBlue 28W Foldable Solar Charger
- Our Analysis, Comparisons, and Test Results
- Should You Buy the BigBlue 28W Foldable Solar Charger?
- What Other Portable Solar Panels & Chargers Should You Consider?
- Specifications
- Conclusion: BigBlue 28W Foldable Solar Charger
Best Solar Charger with Digital Ammeter
BigBlue 28W Foldable Solar Charger
- Rated power: 28W
- Real USB output: about 20W (5V/4A)
- Ports: 2x USB-A (ammeter model)
- Weight: about 1.3 lb
- Cells: monocrystalline, 25.4% rated
- Water resistance: panels only, keep ports dry
Bottom Line : The most reliable small USB solar charger here, so long as you accept it tops out near 20W of real USB output, not the 28W on the label.
Pros
- Ammeter helps you aim for peak current
- Auto-reconnect after clouds pass
- Light and packable
- Strong value near 60 dollars
Cons
- Real USB output near 20W, not 28W
- 5V only, weak for laptops
- No built-in battery
Our Verdict: BigBlue 28W Foldable Solar Charger
The most reliable small USB solar charger here, so long as you accept it tops out near 20W of real USB output, not the 28W on the label.
A four-panel fabric folder with a built-in ammeter so you can angle it until the current reading peaks, which is why it stays ahead of a phone's drain on the trail.
What's the bottom line?
Usually sells around 60 dollars, cheap for a charger that testers rank near the top.
The ammeter version costs a little more and adds bulk, but it lets you aim the panel by the numbers.
I loved watching the ammeter climb as I tilted it into the sun, but do not expect a laptop to move much on 5V USB.
Ryan, Top-Notch field tester
Reasons to buy:
- Ammeter helps you aim for peak current
- Auto-reconnect after clouds pass
- Light and packable
- Strong value near 60 dollars
Reasons to avoid:
- Real USB output near 20W, not 28W
- 5V only, weak for laptops
- No built-in battery
Our Analysis, Comparisons, and Test Results
The BigBlue 28W Foldable Solar Charger scored 88 out of 100 overall.
It is strongest on value for money and weakest on multiple device charging speed.
Here is how it did on every metric we tested, with exactly how each score compares to the rest of the field.
Value for Money
Usually sells around 60 dollars, cheap for a charger that testers rank near the top.
The ammeter version costs a little more and adds bulk, but it lets you aim the panel by the numbers.
You still need to supply your own power bank, since there is no battery built in.
| Value for Money | Rating |
|---|---|
| Best in test | 9/10 |
| BigBlue 28W Foldable Solar Charger | 9/10 |
| Category average | 7.9/10 |
| Worst in test | 7/10 |
Charge Interruption Recovery
An auto-reconnect circuit restarts charging on its own after the sun returns, so it does not sit dead after a cloud passes.
OutdoorGearLab found it kept charging in cloudy and less than ideal light better than most rivals.
You might be wondering:
All four panels must see sun at once, and shade on even one panel cuts output sharply.
| Charge Interruption Recovery | Rating |
|---|---|
| Best in test | 8/10 |
| BigBlue 28W Foldable Solar Charger | 8/10 |
| Category average | 6.1/10 |
| Worst in test | 5/10 |
Charging Speed
Rated 28W, but the two USB ports share a 5V 4A ceiling, so real output is about 20W.
OutdoorGearLab measured 2,177 mAh in one hour of direct sun and 583 mAh in indirect light.
One owner reported almost no gain on an iPhone and MacBook after four hours of sun, a reminder that laptops need more than 5V USB can give.
It charges a 10,000 mAh bank fully in a few sunny hours, or roughly 70 percent across a cloudy hiking day.
| Charging Speed | Rating |
|---|---|
| Best in test | 9/10 |
| BigBlue 28W Foldable Solar Charger | 7/10 |
| Category average | 7.4/10 |
| Worst in test | 6/10 |
Multiple Device Charging Speed
Two USB-A ports let you run two devices, but the 5V 4A budget then splits between them.
OutdoorGearLab found charging one power bank, then charging devices off that bank, was faster than splitting the panel.
Fine for a phone plus a headlamp battery, not for two hungry devices at once.
| Multiple Device Charging Speed | Rating |
|---|---|
| Best in test | 7/10 |
| BigBlue 28W Foldable Solar Charger | 6/10 |
| Category average | 6.4/10 |
| Worst in test | 5/10 |
Durability
Thick canvas backing showed no real wear after heavy testing.
One owner ran it over 1,300 miles of backpacking and bikepacking with only cosmetic scratches.
The panels themselves shrug off rain.
| Durability | Rating |
|---|---|
| Best in test | 9/10 |
| BigBlue 28W Foldable Solar Charger | 8/10 |
| Category average | 7.5/10 |
| Worst in test | 5/10 |
Weight & Portability
About 1.3 lb, light for a 28W panel, and folds to roughly the size of a tablet.
Carabiner loops let it hang off a pack lid to charge while you walk.
The ammeter model adds a couple of ounces of bulk over the plain version.
| Weight & Portability | Rating |
|---|---|
| Best in test | 10/10 |
| BigBlue 28W Foldable Solar Charger | 9/10 |
| Category average | 7.6/10 |
| Worst in test | 5/10 |
Should You Buy the BigBlue 28W Foldable Solar Charger?
The most reliable small USB solar charger here, so long as you accept it tops out near 20W of real USB output, not the 28W on the label.
It is best suited to backpackers topping up phones and small power banks.
Want to know the best part?
The big win: Ammeter helps you aim for peak current.
The main compromise: Real USB output near 20W, not 28W.
We scored it 88 out of 100.
What Other Portable Solar Panels & Chargers Should You Consider?
Not sold on this one? A few others from our testing are worth a look.
The ALLPOWERS 21W Foldable Solar Panel Charger is our best foldable solar charger. A tiny, cheap 21W folder that sips power well in full sun but nearly gives up in cloud or shade.
The BLAVOR Solar Power Bank 20000mAh is our best solar power bank. A solid 20000mAh power bank first and a solar charger a distant second, since its little panel only trickles.
The Jackery SolarSaga 100W Air Solar Panel is our best solar charger for camping. A genuinely light 100W panel that comes close to its rating in full sun and adds a small bifacial bonus over reflective ground.
Specifications
| Rated power | 28W |
| Real USB output | about 20W (5V/4A) |
| Ports | 2x USB-A (ammeter model) |
| Weight | about 1.3 lb |
| Cells | monocrystalline, 25.4% rated |
| Water resistance | panels only, keep ports dry |
Conclusion: BigBlue 28W Foldable Solar Charger
After testing it against the other top portable solar panels & chargers, the BigBlue 28W Foldable Solar Charger earns its place as our best solar charger with digital ammeter pick.
Its standout strength: Ammeter helps you aim for peak current.
So:
The main thing to weigh before you buy: Real USB output near 20W, not 28W.
If you want backpackers topping up phones and small power banks, it belongs at the top of your shortlist.
Still comparing? See exactly where the BigBlue 28W Foldable Solar Charger ranks against the full field in our 9 Best Portable Solar Panels & Chargers guide.
