Solar panels not working during the day?

[Nostrodamus]

Why do weird things always seem to happen to me.
I have 3 semi flexible solar panels mounted on the coach roof that run into 2 mppt boxes.
For some reason they work fine first thing in the morning and last thing at night but switch themselves off during the day.
We are in the med and I suspect it is because they are too hot.
I did ask someone else with solar panels and he was getting less amps when the temperature went up.
Any suggestions?

 

[Rigger Mortice]

I have a panel that sometimes has zero output. There's a poor contact/broken circuit inside it somewhere. I can waggle it around a bit to get it working again, but I'll have to get around to replacing it.

It might be worth checking that it really is all three panels that are faulty.

 

[Hadenough]

I take it the mppt boxes are regulators? I have 240w of solar and over the last week of sunshine (in the UK believe it or not), the regulator has been dumping the charge during the day because the batteries are fully charged. I monitor the daily AH input and have noted that on sunny days recently I have benefited by fewer AH's, purely I assume because the meter records what goes into the batteries so when the regulator dumps the charge I record fewer AH's. What state are your batteries in? If they are charged you may be worrying about nothing.

 

[Hadenough]

View attachment 43485
View attachment 43486
View attachment 43487

First pic is the voltage of battery bank 1, 14.2 is a sunny blip, they normally float at around 13.6 on solar. Second pic is the solar input. As you can see the batteries are fully charged and because it's sunny the regulator has dumped most of the solar input. Third pic is the max input today. I've been off grid for over ten days now running a fridge and all the usuals, only charge has been from the solar and maybe two hours of engine.

 

[Birdseye]

All solar panels give lessleccy as their temperature rises - its the physics of them. As for switching off. Well thaxt shouldnt happen.

 

[Nostrodamus]

Batteries are 2 months old and as we are at anchor they are not fully charged.
They work fine in the early morning and at last light but not during the day
Interestingly enough I put the portable generator on yesterday during the day and they began to work.

 

[Rigger Mortice]

Are you getting zero from them or just less?
What controllers do you have?

 

[LadyInBed]

They will be wired in parallel so one faulty panel will bring them all down.
What are their individual open circuit voltages first thing and around midday?

 

[Pagetslady]

They will be wired in parallel so one faulty panel will bring them all down.
What are their individual open circuit voltages first thing and around midday?

Will the panel be damaged if disconnected when charging ? My regulator reduces the amps when the batteries get near full charge.

 

[VicS]

Why do weird things always seem to happen to me.
I have 3 semi flexible solar panels mounted on the coach roof that run into 2 mppt boxes.
For some reason they work fine first thing in the morning and last thing at night but switch themselves off during the day.
We are in the med and I suspect it is because they are too hot.
I did ask someone else with solar panels and he was getting less amps when the temperature went up.
Any suggestions?

exactly what are the MPPT controllers. Make ? type?

how have you connected 3 panels to two controllers

Are you sure you dont have controllers with the facility to switch lights off during the and have wired the battery to the load terminals instead of to the battery terminals.

 

[Davegriff]

I'd heard of MPPT controllers but didn't know what they did. This seems to explain them...

http://www.solar-electric.com/mppt-solar-charge-controllers.html

 

[LadyInBed]

Will the panel be damaged if disconnected when charging ? My regulator reduces the amps when the batteries get near full charge.

Turn off or disconnect the MPPT Charge Controller from the batteries, then you can seperate the connectors up at the solar panals.
Put voltmerer across the two wires from each panel in turn and record the voltage.

 

[Nostrodamus]

I have 2 x 70 semi flexible panels wired in series to one mppt controller ans one 140 amp solar panel wired to another so if one box failed then I would still have the other. The mppt boxes are quiet cheap (called sol -1) and the positive goes to the house batteries and the negative to the boat main negative shunt which is near the batteries.
As I say both work in the morning and night as they are doing now ( batteries currently at 12.5 ) but stop during the day.
I will try and get a reading when they turn off but I suspect it will be nothing.

 

[charles_reed]

Why do weird things always seem to happen to me.
I have 3 semi flexible solar panels mounted on the coach roof that run into 2 mppt boxes.
For some reason they work fine first thing in the morning and last thing at night but switch themselves off during the day.
We are in the med and I suspect it is because they are too hot.
I did ask someone else with solar panels and he was getting less amps when the temperature went up.
Any suggestions?

I'd suspect that the batteries are being fully charged and the Mppt regulators are doing their job and cutting out.

My amps-input is highly variable, according to the state of charge of the batteries - varying from 18 amps down to 1.4.

At what is your float voltage set - if that is on the low side it will exacerbate an early cut-out - mine is @ 14.4volts.

As to overheating, providing they have some air-circulation on their underside it's unlikely.

 

[charles_reed]

I have 2 x 70 semi flexible panels wired in series to one mppt controller ans one 140 amp solar panel wired to another so if one box failed then I would still have the other. The mppt boxes are quiet cheap (called sol -1) and the positive goes to the house batteries and the negative to the boat main negative shunt which is near the batteries.
As I say both work in the morning and night as they are doing now ( batteries currently at 12.5 ) but stop during the day.
I will try and get a reading when they turn off but I suspect it will be nothing.

As the sol1 MPPT controller is rated @ a maximum of 100 watts (probably @ 55N) and you're putting 140 watts through each (probably @ 39N), I think the suggestion of bypassing them would be the simplest rectification - they're probably blown.

 

[VicS]

As the sol1 MPPT controller is rated @ a maximum of 100 watts (probably @ 55N) and you're putting 140 watts through each (probably @ 39N), I think the suggestion of bypassing them would be the simplest rectification - they're probably blown.

+1

the Sol1 controllers are unsuitable for the power of the solar panels installed

My suggestion would be to replace them with adequately rated controllers

 

[Rigger Mortice]

I have 2 x 70 semi flexible panels wired in series to one mppt controller ans one 140 amp solar panel wired to another so if one box failed then I would still have the other. The mppt boxes are quiet cheap (called sol -1) and the positive goes to the house batteries and the negative to the boat main negative shunt which is near the batteries.
As I say both work in the morning and night as they are doing now ( batteries currently at 12.5 ) but stop during the day.
I will try and get a reading when they turn off but I suspect it will be nothing.

IIs there a reason for wiring them in series (and thus presumably putting a nominal 24volts into the charger) rather than wiring them in parallel to put 12volts in?

 

[LadyInBed]

IIs there a reason for wiring them in series (and thus presumably putting a nominal 24volts into the charger) rather than wiring them in parallel to put 12volts in?

+1 this instalation sounds suspect.
Or maybe the OP is confusing series with parallel.
If the two 70's are in parallel then they will be connected together with Y connectors.
If in series there will be no Y connectors, the two 70's will be dasey chained.

 

[neil1967]

Front cover of the controller states input voltage 12-20V (data sheet says max 24v solar panel voltage). If the 2 panels are in series, then I suspect they are producing in excess of 24v when fully illuminated and hence causing the controller to shut down.

Neil

 

[Nostrodamus]

My mistake.. they are in parallel not series...
One of the reasons I am using 2 mppt boxes is that the 70 solar panel goes through one and the 2 x 35 watt panels go through the other.
As they are semi flexible they are stuck to the coach roof making no real ventilation under them but even so, just after they go off in the mornings I have flt them and they are quiet cool.
Also they did come on in the heat of day when the generator (portable) was switches on.