Solar panel battery level

I have a solar panel connected close to one month. I’ve noticed battery voltage fluctuations a couple of times, see example attached. Voltage drops to ~2.6 V and then comes back to 3.2 and more.

Is this normal or should I be worried?

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The graphic does not look right - I just checked the battery voltage graphic for my SKY unit and the lowest voltage I saw was 3.30 volts in the middle of the night after a few days without bright sunshine…

Might be better to contact WeatherFlow technical support. :thinking:

That is not unusual. The SKY reads battery voltage only every 10 minutes and it is a low priority process so sometimes gets skipped. With the SPA I have noticed more 2.x volt readings and not the typical near 0V readings I saw with the Lithium batteries. I have three SKY units and all three demonstrate the same behavior and one of the SPA units is an original field test unit so has been running for several months.


Since I installed the solar unit back in spring it has been working fine. Over the past month or so I have been noticing the voltage dropping and in the past few days, on cloudy days, it drops to 2.26 and stops. Any suggestions?

just to make sure… you did remove the batteries before installing the solar unit? other then that I would say it is broken.

Please let us know your station ID.
I had a similar behaviour a couple of weeks ago.
Contact @WFsupportx directly, they have to have a look onto. Maybe they will change the SOL.

Raspberry field Mill rd is the station ID. I contacted support and after verification that I had removed the batteries from the unit, I was sent a new SOL. Now a week after the new one was installed I’m having the same thing happening. I contacted support again and they are going to send out a new SOL. Just thinking… could the sky unit be drawing that much power, causing the SOL to drain down???

The station ID is a number. You can find it by using the share icon in the app or website or going to Settings, Stations, station name, Status. The top line should be the station. Here is an example of my station.

Sorry for the omission. The station number is 6952.

Thanks for you assistance.


I had a similar problem with my solar and got a replacement. It gave 1,7V when there was no sun and 3,4V when the sun was shining. I disassembled the old one and it had waterdamage on the printed board and the battery had leaked so probably one of the cells are broken.



I sure hope tech support is following these threads closely.

This is a wonderful product concept, I really want to see it succeed, unlike other units in this price class (like the one with the camera) which seem to “reliably” fail at two to three years.

IMHO, even in this price class, we should expect at least 4-6 years of good operation before failure.

Heck, if the company continues to make significant improvements, many of us will buy the next model before end of life failure. But, not if they start failing at a couple of years from water and/or battery damage.

IIRC, the SPA design life was 5+ years. WeatherFlow is very good at taking care of issues.

And the solar panel finally died after 2 months in use. Quite disappointing. Sky is offline. After so much effort to have the station installed in a great remote location. @WFmarketing is very helpful but that doesn’t help me climbing on that pole. It is the hardware quality which is not on par to competition. It is OK for garden use but not for continuously rough conditions. Another station type has been on that pole for 6 years now with no such issues.
I’m getting a new Sky in a few days but hesitate to install it there :pensive:

I think failures of the solar assembly are exceedingly rare based on an almost total absence of failure reports like yours. That doesn’t help you and I feel your pain.

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The failure of the solar power accessory is not that rare.

I have a solar power accessory installed on my SKY and on my AIR.

The solar power accessory on my SKY has ‘died’ a few days ago (on the 19th). It is odd that the solar power accessory on the SKY, which is directly exposed to the sun for quite a few hours a day, has gone bad, whereas the solar power accessory on the AIR, which is not exposed to the sun (only to ambient light), is still going ‘strong’ - and that is the one I was expecting to fail the first.


That doesn’t surprise me since the Air can run on a battery pack half the size of that in the Sky and do so twice as long. If the SPA on the Air dies when the battery is relatively full you won’t know for quite some time.


The battery level of the SPA powering the AIR unit has been at 3.33 volts since Wednesday (20:55) and before that, oscillating between 3.34 and 3.35 volts since Tuesday (07:05).

Over the past 4-5 days, it has been cloudy with intermittent rain - even the ambient light is probably too low to even charge the batteries…

The battery in the SPA is a LiFePO4 battery with an open circuit terminal voltage of 3.38V at 100% SOC. Temperature will affect voltage somewhat. Also remember that the voltage reported by the AIR/SKY is what it sees and is not the battery terminal voltage directly. The voltage stays very flat throughout the discharge then drops quite rapidly at the end. For my cycle applications I use 3.00V as my open circuit cutoff voltage to leave ~5% buffer in the cell. Here is a graph showing several discharge rates. The yellow (top) curve is close to what the discharge curve of the SPA would be like when powering the AIR. The only difference is that the AIR is drawing well under 0.1C of that yellow curve.

Though I haven’t tested it, I wouldn’t be surprised if a fully charged SPA could run an AIR for 6 months with no light getting to the solar panel.


You are probably right about the ‘life expectancy’ of the SPA on the AIR unit.

The SPA was installed on the AIR unit on May 25, 2019 - as of this morning (09:30) it is still showing 3.33 volts … and the area has not had ‘clear’ sunshine (without heavy/thick clouds) in almost a week.

The list of failures is growing longer, something appears to have gone wrong. Possibly a production issue?