Another thing is in parallel your panel current should be doubling and the fact that is not leads me to believe perhaps the MPPT algorithm is not making adjustments to the changes you made. If you lay your panels flat and say you get 17V and 8A for each of them when laid flat, if you connect them in parallel you should get around 17V and 16A. A firmware update may be available to fix this irregularity perhaps. I am assuming of course the cables and the connectors are rated to handle 16A in the configuration and not the 8A limit of the XT60 connector as stated before. I’m not 100% on all of this just food for thought. So is the array in parallel truly limited to 8A based on what cables and connectors you have is what I’m saying essentially. If the cables and the XT60 ARE rated to handle the 20A then possibly a firmware update can fix this. If its a physical limitation, then no software update will ever fix it. You can do your part by eliminating outside variables such as making sure both panels are not shaded and are perfectly aligned.
I vote for something wrong. Both panels were flat on the ground pointing just about straight up at the sun. The voltage just went over 35 and the watts remained the same - 119.
I assume the cables that came with Bluetti are OK. There is one that is attached in series from one 200W panel to the other…They don’t seem different in size to the Bluetti’s, though.
Thanks - I will get in touch with technical support.
When laid flat your power output should be the trigonometric SIN of whatever the altitude of the Sun is minus around 10%. So if the Sun is at 50 degrees currently you will get SIN(50) or 0.76 . 76 - 10 = 66% power. For a 200 watt panel that should net you at least 125W. Assuming panel is not shaded, not dirty, no haze in sky, etc. obviously. For every 10 degrees F above 77F the panel may lose about 2% efficiency. Assume your panel is 140 degrees. 63 degree difference would be 6.3X2 or another 12% loss. 66-12 would be 54% or 108 watts from a single panel laid flat. In other words a 140 degree F solar panel will produce 12% less power than one at 77 degrees F.
Right. Not even close…
No harm no foul contacting support! Something seems awry when you told me the newer panel was only pushing 55W compared to the other one at 87W. Best of luck.
Thanks for all your help - I have learned a lot. I will update when I know more and if you or anyone else has any more ideas I am all ears.
I still come back to this forum post
““I am asking because I am not sure if there is something wrong with my PV200 panel. It has been peaking at only about 135 to 140 watts output in direct sun, which equates to only about 65 to 70 percent in pretty good conditions.”
That’s the best I get from two panels. There’s got to be a way to do better. :)
Hi @Cort, Thank you for the information provided. We have reviewed it and consider the situation to be normal.
There are many factors affecting solar input. Could you please let us know roughly where you are located? Please check the local lighting conditions. In most areas, it is difficult to achieve an 80% solar energy conversion rate.
In addition to environmental factors, the installation should also be checked. The solar panel should be tilted and oriented vertically to maximize solar absorption. Meanwhile, please clean the panel surface regularly. Humidity can also have an impact.
Finally, please inspect the XT60-MC4 connector for oxidation or looseness, and ensure the connection cable length does not exceed 10 meters (excessive length may cause a voltage drop ≥3%).
Thank you to @Selfmadestrom and @sealy1986 for their attention to and resolution of this matter.
Flagstaff, Arizona - I will clean them and see what happens.
Meanwhile, I asked two AI engines, at midday in June in Flagstaff, Arizona, how much energy two 200-watt portable solar panels should produce.
AI Perplexity - On a clear June midday in Flagstaff, expect your two 200-watt portable solar panels to produce about 315 watts combined—possibly a bit more under ideal conditions, or a bit less if factors like heat or panel angle are suboptimal
Chat GPT - At midday on a clear June day in Flagstaff, Arizona, solar conditions are excellent due to the high elevation (~7,000 ft) and low humidity, which reduces atmospheric attenuation of sunlight.
Estimate of Solar Power Output
Two 200-watt portable solar panels (total: 400W rated power) can be expected to perform near their rated capacity under ideal conditions. Here’s how to estimate real-world output:
| Condition | Expected Output |
|---|---|
| Optimal (cool, clean, angled) | 360 W |
| Realistic Midday Average | 320–340 W |
| Suboptimal (hot, flat, dusty) | 280–300 W |
I’m getting less than half of what they consider to be “suboptimal” results.
I will clean them and see what happens.
I’d read somewhere that dirt didn’t really affect solar panels so I never cleaned them.
When I cleaned them - the power jumped up from 55 watts to about 115 watts and then up to 165 watts at 4 pm in a somewhat cloudy afternoon (!!!) - but then it went back down to 55 (maybe because it was cloudier). The light is too variable right now, but there’s clearly hope.
I will check back when I have clearer skies
Thanks for the idea. :)
Absolutely dirt can kill the panel’s performance. I glazed over your video and didn’t pay close attention, but now rewatching it again your panel was CAKED! The panel doesn’t even have to be entirely caked, just caked in the wrong spots where the bypass diodes would kick in. I’ve read as much as 25%. So 2 panels would be 50% loss in power which is at max 200 watts. You said the highest you got was around 180’ish if I remember. Makes perfect sense.
Things were looking good, but no dice. Cleaned panels are putting out 125 watts again in full sun at midday. Very confusing!
And when you separate them what is the volts + amps of each “clean” panel. Also what is the latitude of your current location?
48 and 56; latitude - 35.198284
Yeah that is clearly not right. I have the original PV200 plugged into my Bluetti power station that only outputs 8A max and its still getting over 100 watts right now where I’m at with some cloud cover AND I’m 10 degrees higher in latitude than you are. There have been several complaints about the newer series panels not performing to expectations. Myself included. I have the newer PV350 and its performance is not up to par. Had it replaced. Same exact performance. @BLUETTI_CARE Please forward our concern to your internal quality control team to look at the performance of your new folding solar panels. They do not appear to be up to par with previous generations.
Thanks - this is getting more and more interesting.
I have 4 solar panels on the top of the van dating back from 2016 and (for the first time) I used the volt meter to assess their power output (volts x amps = watts) from 3-4 pm and compared them to Bluetti portables.
Solar panels on the van - not tilted towards the sun
- 2016 - Grape 160 W - 83.4 W
- 2019 Newpowa 175 - 153 W
- 2019 Newpowa 175 - 58 W (ouch!)
- 2025 Renoga 170 - 131 W
The Bluetti 200W portables tilted toward the sun.
I was unable to access the leads as they are covered up, and sticking the Klein meter prongs into the connectors didn’t work. The Bluetti app told me, though…
- Bluetti 200 W portable -(12/30/2023) - 84 W
- Bluetti 200 W portable (11/24) - 40 W (!)
The almost 10-year-old Grape 160 - lying flat on the van - is doing as well as the 12/2023 200-watt Bluetti - tilted toward the sun, and the newer 200-watt Bluetti is doing the worst of all. (If one was going to do worse I’m happy it was that one as I never liked it - it’s stiff and awkward and hard to prop up properly)
I am just learning this stuff, but unless I have something wrong, my Bluetti 200-watt portables are really underperforming…
That’s really surprising to me as Bluetti has an excellent reputation but I did go through 2 AC 180s after the charging outlet failed on them 3 x’s (once after Bluetti repaired one of them). (Bluetti was good enough to refund all the AC180s, and I now have the AC200, which so far has been superb.)
My next step is probably to get a portable 200W panel from a different manufacturer and test it.
In the meantime I will assess them tomorrow. Those two panels should not have dropped that much - they should last 20 years).
(I will also probably replace at least one of the solar panels on the van).
I recently acquired a newer Bluetti power station that has “PV Pro” setting available in advanced setting. I noticed that if you set the DC input source set to “Other” it capped the power station around 50W using my PV200 (Gen 1). If I switched the DC input source back to “PV” I got around 135 watts with PV Pro enabled. Likely not your problem just sharing for others. The 50W limitation can be user induced though as I’ve demonstrated. Hopefully Bluetti reviews our concerns and addresses the concern. As one of your panels is still under warranty, you have a valid case for a replacement. I completely agree with the design flaw of the new panels. They are WAY too awkward to prop up. I feel like it is going to collapse on itself and the panel will get damaged easily.
Thanks.
I just retested everything - sun straight overhead and the app said the newer panel was producing about 40 watts. (The older one - 80 watts).
I still don’t know if the Bluetti is tamping down the power from the panels - I will need to buy a non-Bluetti panel to test that - but at least the newer panel is doing extremely poorly.
Interestingly, the power from the Bluetti portables was the same with the sun straight overhead and at 4pm yesterday, with them tilted. The solar panels on the van, on the other hand, produced more energy with the sun straight overhead.
With the results similar to yesterday’s tests I feel confident about the results. I don’t know that I could be doing wrong.
You have multiple data points to demonstrate that the performance is not the direct result of the environmental conditions itself as the nearly 10 year old flat mounted panels at 25W less watts produce more output in the exact same conditions.
BTW the power station you are performing these tests on is a “Elite 200” and not an AC200 correct? AC200 has a minimum PV input voltage of 35V and I read that at the very low end of the spectrum it can output very low amps, which would explain the poor performance, but in your video you had an Elite 200 which operates 12-60V @ 20A max. You do have an ELITE 200 V2 not a AC200, correct?
On the other side of the coin I did see in past threads where MPPT controller was unstable for some on their Elite 200 V2. It would pull higher voltage initially when they connected their panel in series, and then a few seconds later capped to 16V. At that voltage your output would be low. This still doesn’t explain why the one panel is 80 and the other is 40 though, which is why I vote for “something wrong with panel”.
Hi @Cort, Thank you for providing the detailed information.
We have consulted the R&D department and confirmed that the open-circuit voltages of PV200S and PV200D are different, so they cannot be used in series or parallel. Please select panels of the same specification and connect them in series to charge the AC200. This might also be the reason for the low charging power.
Thanks to @sealy1986 for the explanation. Indeed, when the surface of the solar panel is dirty, the light transmittance decreases, and sunlight cannot directly shine on the battery cells. The degree of attenuation is proportional to the level of dirt.