Some devices have a minimum power cut off, if your roof 380W panel are only generating 35W, then a 120W PV would do maybe only 10W, though I would think 2 in parallel should do 18W with some additional losses and mismatch. While it isn’t ideal, I am not surprised that it won’t take a charge when there is so little power available.
Is it a cloudy day? Where do you live where sun in winter produces <10% of solar panel power?
I have another brand solar charger / inverter / battery combo, and I do noticed a similar no charge at lower sun input situation. When there are lots of clouds, the power would drop to 0W. Actually the MPPT would try to charge and power would go from 0-10-20W and then back to 0W, stay there for 10s and cycle again. I am running 2s 120W into it. This issue may not be unique to Bluetti
I have another brand solar charger / inverter / battery combo, and I do noticed a similar no charge at lower sun input situation. When there are lots of clouds, the power would drop to 0W. Actually the MPPT would try to charge and power would go from 0-10-20W and then back to 0W, stay there for 10s and cycle again. I am running 2s 120W into it. This issue may not be unique to Bluetti
If the EB3A recovered after 10s, it would be fine, but once the charge falls to 0W it will never recover without manual intervention, and instead of charging it will drain the battery 1-2% per hour with no load connected. That is unique to the EU version of EB3A, even other Bluetti power banks do not have this same issue.
@Arkku Are you charging on a cloudy day? The input power will be very low this way. When the solar panel’s ISC reaches the EB3A input current minimum, its input voltage will decrease rapidly as the input power gets smaller, and a PV low voltage error will be reported when it is less than 12V.
Are you charging on a cloudy day? The input power will be very low this way. When the solar panel’s ISC reaches the EB3A input current minimum, its input voltage will decrease rapidly as the input power gets smaller, and a PV low voltage error will be reported when it is less than 12V.
@BLUETTI_CARE I understand that on cloudy day or at night this error state may appear. That is not the issue. The issue is that once this error state appears, it does not go away when the light improves, and the battery is drained while in this error state even with no load connected.
Again, please consider this example:
I plug in the panel in good sunlight, get 50W charging
Time passes and sun starts to set, now I get only 1W charging
Sun sets and panel is still plugged in, but there is no light, so charging stops (0W)
Sun starts to rise, first rays of light would give 1W charging, but the voltage is too low to start → PV voltage low error state happens, and battery drains at 1-2% per hour even with no load
Sun has risen, now there would be 50W charging again, but because PV voltage low error state it won’t charge and instead battery continues to drain 1-2% per hour
Steps 1–3 are normal and understood, it depends on amount of light. Steps 4 and 5 are the problem: if the charging ever starts from 0 to less than 18W, it will go into PV voltage low error state and not recover. So, it is not possible to leave panel plugged in overnight or unattended, because sun setting (or heavy cloud appearing) will enter the persistent error state and drain the battery.
(I’d also like to reiterate that this same issue has been reproduced by several other users more than 6 months ago, and appears to have been specifically fixed in the US version firmware update, so at some point someone at Bluetti has understood and acknowledged this problem, but EU version is still not fixed. See linked threads from first post.)
I received a firmware update to DSP version 2052.09 now. I tested it as follows:
2 pm: EB3A at 90% charge and nothing connected, DC off: plugged in the PV68 panel, but there was no direct sunlight: the “PV voltage low” error appeared as before, so the solar charging still can’t start under 18W
3 pm: EB3A at 89% charge, still no direct sunlight and showing the error, so the battery is still being drained in this state
4 pm: EB3A at 88% charge, but now the sun has moved so that the panel is getting direct sunlight: charging at around 25W
After that, I experimented by moving the panel partially to shadow, and found that the charging would stop at around 11W completely, and start at around 20W when moving it back
(edit: added this point) 6 pm: EB3A at 93% charge, now the sky is overcast, but no error state and the app shows that it is still charging at 1W – so, low W charging is still possible if it slowly drops to it
In conclusion: the firmware update is a definite improvement in that it makes the PV voltage low error recoverable, but does not fix all issues. Specifically, it fixes one of three related issues:
Once the PV voltage low error state happens, it was not possible to restart charging: this is fixed now by the .09 firmware
The battery is drained by 1-2% per hour while the PV voltage low state occurs: this is not fixed, so leaving the panel plugged in might still lead to a temporary drain on the battery (perhaps over 20% drain in total if the error state would persist overnight, and theoretically a complete drain could happen during multiple consecutive cloudy days, so the panel can’t be left plugged in “permanently”)
The charging can’t start at low watts – if even 10W start was possible, this would considerably extend the weather conditions for charging, but I can understand if this is not possible to fix in firmware
So, we are getting some improvements here with the error state no longer “fatal”, but I wish it was still possible to improve the battery drain (e.g., don’t keep the screen on in the PV voltage low error state, if that’s what is causing the drain).
Next day update: the EB3A and PV68 have been plugged in for over 24h now. The battery went down to about 70% charge (from original 90% and peak about 94%) due to the PV voltage low state draining battery, since it has been cloudy today. So leaving the panel plugged in is still a gamble where you may well lose charge rather than gain it…
In the evening it is charging at 1W again; there was a momentary ray of light that turned on the charging, now it is cloudy again.( I don’t really understand why it is possible to continue charging at 1W but not start charging at 1W…)
edit: Next day update #2: another cloudy day, now it is charging at 3W but the charge is at 55%, so leaving it plugged in is still a net negative.
Hi, it is not suggested that you connected the solar panel overnight. That would cause much consumption than disconnect the solar panel. Furthermore, I contacted Bluetti Technician, and received a reply that currently there is no firmware can help to decrease consumption.
I agree that not leaving the solar panel plugged in overnight does solve the battery drain, but I do not think it is an acceptable limitation for the product that you can only solar charge it under constant supervision or it will result in negative charge…
I am in Australia and purchased my EB2A in April. I am having the same issue, connected to the solar panels in full sun for 3 hours, there was as drop of 4%.
Not charging from solar panels response from Sale-au within hours, this is the reply.
Sorry for the problem.
Here are the solutions for you:
1. Please check whether the EB3A is fully charged? If yes, it is normal that can not be charged when EB3A reach 100%.
2. If the ‘input’ is flashing, you need to check whether the open circuit voltage(voc) of your solar panel exceed the PV input of EB3A(28V).
3. Please try whether EB3A can be charged by car. If it can be charged by car, then it may the problem of solar panels.
Please use a multimeter to measure the voltage of the solar panel and connecting cable.
We will wait for your feedback. Please provide a video shows the problem then.
My reply.
The EB3A was at 84% when I attempted to charge.
There the “input” was not moving at all. The solar panel does not exceed EB3A’s 28v
The car charger works ok.
Have tested the solar panels and there is no problems there.
@Silverfish When you connect the solar panel, are there any input watts shown on the screen? You can try to upgrade the firmware to check if the problem can be solved. If not, you can try to replace a solar charging cable to check again. If it still can’t be solved, you can ask for the after-sale service and they will offer you another solution.
Thanks for your response. No input watts (or anything) shown on the screen. The firmware is v1.3.12.
The solar charging cable is new, operates fine when charging other items.
Have contacted after-sale service, they have responded, which I appreciate. Have checked off there suggestions but still no success.
The firmware version looks like: DSP 2052.04… The v1.3.12 is probably the app version, not the firmware. You can check the EB3A firmware version from the firmware update menu.
Please tap the “LOGIN” icon to register your BLUETTI account. Fill in your related information to continue and check if there is any firmware in the page.
Just for your information: The underlying problem can be solved by a simple external capacitor in the solar cable - instead of waiting for new FW versions
The details are described at the end of this thread: EB3A Solar input not working
