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Is this unacceptable performance?

David1985

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Joined
Mar 31, 2021
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11
Hi everyone,

I have an AC50s which has 14-40v mppt controller in it and I've hooked up a Dokio 110w panel to it.

The problem is the most I've ever seen going into the battery is 48w. The following readings were taken on a clear sunny day afternoon in Florida.

Cold VOC: 21.8
Cold Amp: 5.9

Hot VOC: 19.4
Hot Amp: 4.95

When under load connected to the AC50s with a 50% battery, I'm seeing panel voltage drops to as low as 12v. I measured the current as well under load and the most I saw was around 3.7. Total wattage hangs around 45w in direct sunlight.

Yes I know I went cheap on the panels, but they do seem to be working fine. Is it that they are only 24 cells? Maybe I should have went with a higher voltage panel. I wasn't expecting 100w, but 80-90 would have been nice.

Is there a way to test what the cause of the low output is?

Thank you
 

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a quick google of dokio 110W shows this:

Vmpp 18v
Impp 6.1A
so...
I wonder if the interconnect between the two folded panels has, well, decided to disconnect itself?
 
I have the same dokio 110 on boat I just put it on Bimini top and it's doing ok around 4-5 amps in summer time .I use only when going on boat and sleep on it for few days and it is charging smaller compressor fridge just ok
 
Good to know. Seems like mine is under performing quite a bit from yours then. I'm angling mine at the sun and still getting under 4 amps. Time to do the whole eBay return talk. Fun.
 
Hi everyone,

I have an AC50s which has 14-40v mppt controller in it and I've hooked up a Dokio 110w panel to it.

The problem is the most I've ever seen going into the battery is 48w. The following readings were taken on a clear sunny day afternoon in Florida.

Cold VOC: 21.8
Cold Amp: 5.9

Hot VOC: 19.4
Hot Amp: 4.95

When under load connected to the AC50s with a 50% battery, I'm seeing panel voltage drops to as low as 12v. I measured the current as well under load and the most I saw was around 3.7. Total wattage hangs around 45w in direct sunlight.

Yes I know I went cheap on the panels, but they do seem to be working fine. Is it that they are only 24 cells? Maybe I should have went with a higher voltage panel. I wasn't expecting 100w, but 80-90 would have been nice.

Is there a way to test what the cause of the low output is?

Thank you
I just wonder how they can pretend such values with just 24 cells, that's just impossible!
A regular 100W panel with 18VMpp has 32 cells.
Everything but glass panels is IMHO just crap. Resin olds (gets yellow and blocks the energy carrying UV) very fast under sun irradinace and real cells aren't flexible.
Under 100W with panels advertising 18V MPPT a PWM controller is frequently the better choice.
MPPT needs a good voltage gap to become efficient.
But I will be ready to bet with you that your "MPPT" Dokio controller is just a plain PWM device.
 
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I did some digging and it seems like they may have sent me a panel other than the 110w.

In this link here from Wish.com, the image for the 110w has 36 cells. At least the first image anyways. Mine definitely has 24 so time to bring that up with them.
 

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That is in July and August ...and I like dokio it's cheap and get the job done .I left his connector on roof when going for few days on boat I. Just plug it in and have power for portable fridge
 
I did some digging and it seems like they may have sent me a panel other than the 110w.

In this link here from Wish.com, the image for the 110w has 36 cells. At least the first image anyways. Mine definitely has 24 so time to bring that up with them.
Indeed the two pictures are different: the first one has 24 full size cells (will bring ~12V MP), the second 36 rectangular cropped cells which will bring 18v MP, but less amps.
Anyhow with these 36 * 3/4 sized cropped cells you should never get 100W normalized power or they are candidates for the next Nobel Prize..
 
So what would you consider an acceptable output from these panels to be under good conditions with the 24 cell or 36 cell versions? The 45w I'm getting on the 24 still seems pretty terrible no matter what. I'm thinking about just getting my money back at this point.
 
MPPT needs a good voltage gap to become efficient.
But I will be ready to bet with you that your "MPPT" Dokio controller is just a plain PWM device.
Yeah it came with a low end PWM, but I'm not using it in this case since the Bluetti has one built in. If I had an extra battery laying around I would try charging that with the controller and see how it compares.
 
So what would you consider an acceptable output from these panels to be under good conditions with the 24 cell or 36 cell versions? The 45w I'm getting on the 24 still seems pretty terrible no matter what. I'm thinking about just getting my money back at this point.
Here in Europe I can buy a serious 100W panel with a usable plain PWM controller for 55€ incl vat, delivered at home in 3days.
But it is 55cm * 100cm large and weighs 7Kg and I get 85W out of it (at 45° latitude ) which is OK.
Your toy stuff of half that size cannot deliver more...
 
Portability and weight were my main determining factors so I'm either going to have to spend more for the Bluetti 120w foldable which performs at full capacity, or use the smallest 100w solid panel I can find - something like this Newpowa. Waiting to hear back from the Dokio people now to see if they can replace it with their 160w foldable.
 
On a fundamental level, what causes the the measured Vmpp 18v, Impp 6.1A to drop to less than 13v and 3.5A when under load charging the Bluetti? Does a higher cell count panel prevent such a drop? Is the MPPT dragging it down to maximize current?
 
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On a fundamental level, what causes the the measured Vmpp 18v, Impp 6.1A to drop to less than 13v and 3.5A when under load charging the Bluetti? Does a higher cell count panel prevent such a drop? Is the MPPT dragging it down to maximize current?
PWM SCCs are switching the panel to the battery on-off. In On state Vpanel = Vbat.
Only of you have a true RMS voltmeter, you will see the mean voltage when they switch.

Then a partial shading will drop the panel power substantially. and low irradation too.

But with 24 cells you can't have a MPPT at 18V. Rule of thumb: ~0,5V per cell under load and ~0,65V per cell no-load.
 
Portability and weight were my main determining factors so I'm either going to have to spend more for the Bluetti 120w foldable which performs at full capacity, or use the smallest 100w solid panel I can find - something like this Newpowa. Waiting to hear back from the Dokio people now to see if they can replace it with their 160w foldable.
There is no consumer grade 100W panel under 0,5m² (everything else is a lie)
That corresponds to 20% efficiency (ignoring interstices) , much more is prohibitively expensive.
 
Portability and weight were my main determining factors so I'm either going to have to spend more for the Bluetti 120w foldable which performs at full capacity, or use the smallest 100w solid panel I can find - something like this Newpowa. Waiting to hear back from the Dokio people now to see if they can replace it with their 160w foldable.
Rich solar also seems to carry some better quality panels.

 
Thank you everyone for the help. The Dokio people are being less than willing to take my panel back. They are like... look at the open circuit wattage, it's 120w! And then told me it is normal for a 110w rated panel to put out less than 50% of its rated output when under load. They offered me a 50% refund and keep the thing. I guess that makes the price per watt a bit better to take. It's still pretty useless though unless I can resell it for more.

As for alternatives, I think I know what I am looking for in the specs.

@Rins67630 - going by what you said, I will also be disappointed by the Newpowa compact 100w panel? Spec on that one attached. It does appear to be too good to be true at that size. It also seems to have 28 cropped cells and then 4 half cropped at the bottom for what I assume is 30 total cells.

@John - that Rich Solar looks like a nice 36 cell panel, but is too long for where it is going to go in the trunk of the car. What might work is.. buying two of their 50w panels, putting them in series, and then connecting them with hinges. My only worry there is possibly exceeding the 40v limit in good sunlight on the Bluetti. Could do parallel but I'm trying to limit wiring complexity with more connectors.

I wish the Bluetti folding 120w folding wasn't so expensive.. hard to justify $300 for 120w no matter how practical it is.
 

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Portability and weight were my main determining factors so I'm either going to have to spend more for the Bluetti 120w foldable which performs at full capacity, or use the smallest 100w solid panel I can find - something like this Newpowa. Waiting to hear back from the Dokio people now to see if they can replace it with their 160w foldable.
I have here two "20W" panels from Dokio solar, I bought them with 8 Weeks difference.
The two delivered panels had the same mechanical dimensions and **exactly the same specification sticker**, but they have completely different cells, both are 36 small square monocristalline cells, that is the only common parameter: electrically, they are behave completely different, the first one (with somewhat bigger cells) delivers in full sun ~12W, the second one with the 10% smaller cells, delivers 18W.
I would never classify Dokio in the range of serious vendors, they probably sell anything that they can catch for cheap, and put their standard sticker on it, without testing anything.

And -as almost EVERY small panel that I could test- their MPPT is~ 15V, far lower than the plate value, indeed best suited for PWM controllers to a 12V battery.
 
Old reply incoming!
I've got one of the Dokio 220watt foldable panels, which has 48 square cells split between the four panels. I've been using this to test with a Victron MPPT controller to charge some small batteries (3s Li-Ion & 4s LiFePO4) here in Texas. So far 130watts is the highest I've seen, with closer to 100watts being the average.

After providing screen shots and photos to Dokio, they sent me a replacement panel as I could prove I was getting about 40% of the rated capacity. The replacement panel does seem to get up to 120watts on average, where the older was averaging 80~90 watts. They've basically given up and said to just keep both of them.

Attached are screen shots showing the type of performance I as getting on a bright sunny day, with the sun nearly overhead. I think the dips were the laptop trying to shut bluetooth off, as they seem pretty regular interval. I suppose it could have been a cloud, but I wasn't outside watching.
Screen Shot 2022-05-11 at 14.33.55 .gifScreen Shot 2022-05-11 at 14.45.00 .gif

Since I now own both panels, I will probably remove the SAE connections as I found their factory cables get far too flexible under load. I was watching the power completely disconnect due to the connector getting soft and breaking contact. I also may try putting both halves into series at the same time I splice in PowerPoles to see if I can get better performance from the panels. This is what it looked like when the connector was hot and breaking contact:
img1.jpg
 
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