Voltage from Panels dropped to 12v - Help please

[Adrianlle]

I have 2x 100w flexible solar panels on roof connected to battery via a VictronConnect 75/15 MPPT controller. Connected to iPhone via dongle that gives me relevant info. . About 4 years old. Always meant we rarely needed hook up. However the readout is now telling me that I haven’t had any solar Charging for last 18 days- when of course it’s been mostly sunny! I know that the Victron needs a difference of at least 5v between battery voltage and panel voltage. Battery voltage during that period is mid to high 12v. Panel voltage output varies but never higher than high 12v. Today for example battery is 12.7 and panels producing 12.4v. 18 days ago panels were producing 18plus v and charging batteries as more than 5v difference. No reason to doubt the VictronConnect readout as voltmeter for batteries confirms the reading.
So any ideas why the sudden change? Ive tried switching everything off/rebooting etc. Hate to think that I might need new panels after only 4 years!

 

[jockaneezer]

My Biard flexible panels only lasted 18 months.

 

[Lenny HB]

I suspect one or both panels, flexible panels don't have a good name for reliability.

 

[tonyidle]

Check the panels when disconnected from the controller. It may not be the panels.

 

[mitzimad]

the flexi panels are not good weve had to change my sons after 3 years

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[Jev88]

If you can take a voltage reading carefully direct from each panel?

 

[Adrianlle]

Check the panels when disconnected from the controller. It may not be the panels.

Yes. It’s a bit of a mission going up the v high stepladder as the Van is 3.1m tall! But that was my next planned move. I have circuit breakers fitted to both the positive input from the panels and in the positive output from the controller to the batteries just in case I ever needed to isolate everything. So I will throw those and then get up the step ladder and take some readings from the junction box for each panel. I suppose that’s the only sure fire way to check what the voltage output of each panel is. Keep the contributions coming as usual and I will report back.

 

[tonyidle]

Yes. It’s a bit of a mission going up the v high stepladder as the Van is 3.1m tall! But that was my next planned move. I have circuit breakers fitted to both the positive input from the panels and in the positive output from the controller to the batteries just in case I ever needed to isolate everything. So I will throw those and then get up the step ladder and take some readings from the junction box for each panel. I suppose that’s the only sure fire way to check what the voltage output of each panel is. Keep the contributions coming as usual and I will report back.

Initially check the voltage near the controller but with it disconnected (assuming you haven't already done so). Only look at splitting the connection on the roof if the first check shows a problem. If the controller has developed a fault it's perfectly possible for it to hold down the panel voltage.

 

[Richard n Ann]

If the panels are producing no current the voltage maybe ok while disconnected but when you connect them the voltage will drop to whatever the battery is.

 

[Adrianlle]

Initially check the voltage near the controller but with it disconnected (assuming you haven't already done so). Only look at splitting the connection on the roof if the first check shows a problem. If the controller has developed a fault it's perfectly possible for it to hold down the panel voltage.

Well it seems to have sorted itself out. First, I remembered that it’s possible to reach the roof junction boxes of the panels by sliding out the roof bed ,opening the big Heki all the way and then crouching through the opening. That enabled me to disconnect the panels and test them with a multimeter. Got around 19v so they seemed ok. Then connected them back up, went downstairs, switched on power to the controller, and immediately working ok. The Victron app showing that the panels are producing around 120w and it’s not yet midday and quite cloudy. I can only think that disconnecting the panels and reconnecting them acted as some sort of reboot of the controller in a way that just switching off the power does not. Any ideas ?

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[Richard n Ann]

Well it seems to have sorted itself out. First, I remembered that it’s possible to reach the roof junction boxes of the panels by sliding out the roof bed ,opening the big Heki all the way and then crouching through the opening. That enabled me to disconnect the panels and test them with a multimeter. Got around 19v so they seemed ok. Then connected them back up, went downstairs, switched on power to the controller, and immediately working ok. The Victron app showing that the panels are producing around 120w and it’s not yet midday and quite cloudy. I can only think that disconnecting the panels and reconnecting them acted as some sort of reboot of the controller in a way that just switching off the power does not. Any ideas ?

Either that, or a bad connection you've disturbed ?

 

[tonyidle]

If the panels are producing no current the voltage maybe ok while disconnected but when you connect them the voltage will drop to whatever the battery is.

I don't think panels can do that - on the other hand a poor connection would have exactly that effect.
Adrianlle - if you turned off the controller by disconnecting it from the battery & panels then it would reset. I think that's the likely explanation.

 

[Adrianlle]

I don't think panels can do that - on the other hand a poor connection would have exactly that effect.
Adrianlle - if you turned off the controller by disconnecting it from the battery & panels then it would reset. I think that's the likely explanation.

Yes that seems the most likely. Handy to know if it happens again. Thank you all for the suggestions and help.

 

[Tony50]

Perhaps someone could advise me ,on a similar problem , I have 2 x100watt panels and 2 x 100 amp batteries , the inside Meter used to go up to 14 volts , now down to 13 volts without Inverter on any ideas please why this has happened I have a Volt Meter but don' t how or where to start and finish checks and what safety things do I have to do before and when doing checks , thanks

 

[denisejoe]

Perhaps someone could advise me ,on a similar problem , I have 2 x100watt panels and 2 x 100 amp batteries , the inside Meter used to go up to 14 volts , now down to 13 volts without Inverter on any ideas please why this has happened I have a Volt Meter but don' t how or where to start and finish checks and what safety things do I have to do before and when doing checks , thanks

Have you tried putting something on in van ie telly might just need to drop a bit

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[Tony50]

Have you tried putting something on in van ie telly might just need to drop a bit

I have tried boiling a low wattage kettle, and Inverter drops out before kettle has boiled , which up to now it always boiled a kettle although the voltage did drop a bit

 

[autorouter]

First thing I'd do is measure the voltage of the batteries directly on the terminals. The voltage of the two batteries should be exactly the same as each other. If not, there is a problem with the battery connections.

Next, measure the voltage at the solar controller, where the battery positive and negative are connected. This reading should be the same as the battery voltage - unless there is a problem with the wiring from the solar controller to the batteries.

Then measure the voltage of the panels, where the solar panel positive and negative are connected to the solar panel.

No special safety precautions are necessary if you are just measuring voltage. Set the meter to the 20V DC range. If you measure the wrong way round with a digital meter, you just get a minus sign in front of the display reading - it's not like the old needle meters that could be damaged by a reverse voltage. You won't get a shock off any voltage below about 40V, so there's no need to worry about that.

Do you know the make and model of the solar controller? Or you could post a pic of it.

 

[Tony50]

First thing I'd do is measure the voltage of the batteries directly on the terminals. The voltage of the two batteries should be exactly the same as each other. If not, there is a problem with the battery connections.

Next, measure the voltage at the solar controller, where the battery positive and negative are connected. This reading should be the same as the battery voltage - unless there is a problem with the wiring from the solar controller to the batteries.

Then measure the voltage of the panels, where the solar panel positive and negative are connected to the solar panel.

No special safety precautions are necessary if you are just measuring voltage. Set the meter to the 20V DC range. If you measure the wrong way round with a digital meter, you just get a minus sign in front of the display reading - it's not like the old needle meters that could be damaged by a reverse voltage. You won't get a shock off any voltage below about 40V, so there's no need to worry about that.

Do you know the make and model of the solar controller? Or you could post a pic of it.

Thanks for info I will do the checks you suggest, thanks again

 

[autorouter]

Then measure the voltage of the panels, where the solar panel positive and negative are connected to the solar panel.

Oops, this should say
Then measure the voltage of the panels, where the solar panel positive and negative are connected to the solar controller.

 

[Off da Grid]

It is possible to have voltage and no current. When the panels are not receiving enough light to generate current.

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[Richard n Ann]

It is possible to have voltage and no current. When the panels are not receiving enough light to generate current.

Yes that's what happens at sunset, the voltage keeps falling steadily and eventually there isn't enough difference for current to flow. Once the panel output gets down to 15v say.

 

[Tony50]

Thanks all for help , checked voltages, as recommended, all even, so I removed Solar panels fuse, so no charge happened, then put on Inverter with low watt kettle, then when Inverter cut out, I switched it off, disconnected the 2 batteries and found one battery was 13.5 volts and the other 12 .8 volts, so I am assuming low voltage battery is on way out