Solar panel realities experiment.

[djgriff]

If the battery is full, your panels will not generate much power.
Try turning on some electrics in the van to draw current from the leisure battery, and see what happens.

You will also only get the full power if the sun is fully out, no shadows, and the panels are directly facing the sun.

Pete

Ok so they are in direct sun light, but the bars would be casting shadows on a small part as shown in the image attached in previous post. Also the battery if 100%. So the reading at the top is just showing what is being used or what is being generated?

 

[Sackmycook]

It's just showing what can go into the battery to keep it 'floating' at full...... have a look at Trends, may make more sense

 

[Pete C]

That’s what the panels are generating and is being passed to the battery.

Pete

 

[djgriff]

cheers, will remove the bars and see if the produced wattage goes up
thanks

 

[Jim Rey]

Aah didn’t realise this would be an issue

The fingers of each photovoltaic cell is linked to other cells so if the output from an array is obscured by an object this might then reduce the efficiency. However as the other guys have pointed out your system is saying that it is in float mode. Drain the battery a bit then remove the crossbars to see if power generated from the solar panel improves

 

[djgriff]

The fingers of each photovoltaic cell is linked to other cells so if the output from an array is obscured by an object this might then reduce the efficiency. However as the other guys have pointed out your system is saying that it is in float mode. Drain the battery a bit then remove the crossbars to see if power generated from the solar panel improves

great thanks, just whacked a whole load of things on and the solar watts jumped up to match the draw so looks all good! thanks for the advice guys super helpful as always!

 

[AussieMick]

i would think the crossbars shading the panel are not a good idea. Even partially shading my panel has a big effect. Try with and without on the same day and time to see what happens.

 

[Dellmassive]

The above showed the battery 100% full.

The charger has moved to FLOAT stage at 13.8v and is trickle charging the battery to keep it full....

.

 

[Raul a/3]

Aah didn’t realise this would be an issue

Big issue, in fact you will get high resistance in the shaded area, as it’s a fixed shade rather than a moving shade. In time you running the risk of burning the diodes and possibly brown spots on the panel.

 

[djgriff]

Big issue, in fact you will get high resistance in the shaded area, as it’s a fixed shade rather than a moving shade. In time you running the risk of burning the diodes and possibly brown spots on the panel.

Yikes don’t wanna do that! Will remove them until I need them! Appreciated the advice!
(bars have been removed!)

 

[djgriff]

Hi, so I haven’t driven for a few days since posting and noticed that the battery level is dropping, so I checked the solar panel app and states it is in float mode and not kicking in to charge it for some reason. Does anyone know what might be going on here, cheers

 

[djgriff]

One more for reference

 

[djgriff]

Ok think I got the issue looks like the smart shunt wasn’t synchronised to 13.2v as 100% full, but set to 14.5v hence the discrepancy. Oops

 

[Raul a/3]

And how it’s the 13,2v going to help you? Re setting the SOC to 100% when there’s 10-15ah still to go?
Re setting prematurely it’s not the solution here. Your solar is weak to fully charge, and is asking for more absorb time.
The shunt detection voltage should match close your charging voltage. I set mine at 14,1v, charger at 14,2v with 2hrs absorb time. Sometimes I get exactly like you, the solar drops into float, but still ah left to put back. I raise the voltage to 14,4v for a couple of days. If that doesn’t clear it, I increase bulk time from 2 to 2.5hrs. Then I revert back to my previous settings.
This scenario happens when cells needs to balance to recover back capacity, and the balance current is small, taking longer to balance.

What you did, you set the shunt parameters to call it 100% to early.

 

[djgriff]

And how it’s the 13,2v going to help you? Re setting the SOC to 100% when there’s 10-15ah still to go?
Re setting prematurely it’s not the solution here. Your solar is weak to fully charge, and is asking for more absorb time.
The shunt detection voltage should match close your charging voltage. I set mine at 14,1v, charger at 14,2v with 2hrs absorb time. Sometimes I get exactly like you, the solar drops into float, but still ah left to put back. I raise the voltage to 14,4v for a couple of days. If that doesn’t clear it, I increase bulk time from 2 to 2.5hrs. Then I revert back to my previous settings.
This scenario happens when cells needs to balance to recover back capacity, and the balance current is small, taking longer to balance.

What you did, you set the shunt parameters to call it 100% to early.

aah ok, didnt realise, i just went back to the manual to see if i missed any settings, as it stated it should be 13.2, I assumed i must have set it wrong.
So these are the setting I have in the smatsolar mppt and the shunt, how would you suggest I set these up if configured wrongly? I set the shunt to 14.1 as suggested. Thanks

 

[Sim60]

I havnt followed your whole story, but why aren’t you using the smart Lithium preset rather than tweaking the advanced settings?

Simon

 

[djgriff]

I havnt followed your whole story, but why aren’t you using the smart Lithium preset rather than tweaking the advanced settings?

Simon

So i am currently using a Acid battery - gel carbon. so don't think the lithium settings would be applicable.

 

[Raul a/3]

So i am currently using a Acid battery - gel carbon. so don't think the lithium settings would be applicable.

Sorry I also wrongly assumed you are using lfp.
For lead are different settings. First you should increase your absorb to max 8hrs, and tail to 1a. Then on the shunt charged detection voltage to 14,2v., charge efficiency 90%. For now.

 

[djgriff]

Sorry I also wrongly assumed you are using lfp.
For lead are different settings. First you should increase your absorb to max 8hrs, and tail to 1a. Then on the shunt charged detection voltage to 14,2v., charge efficiency 90%. For now.

Thanks man apprreciated

 

[Sim60]

So i am currently using a Acid battery - gel carbon. so don't think the lithium settings would be applicable.

Sorry about that - I’m reading too many different threads at once.

Quick question about your setup - is the smart solar connected across the leisure battery only or across the leisure battery and shunt?
I thought the shunt was working out your SOC by measuring charge into battery vs charge out - once 100%SOC set, then battery voltage should be irrelevant. The shunt calculates that the available charge has gone down 8%.

The smart solar is showing 0.1A being generated. The shunt is coincidentally showing 0.1A leaving the battery.
If the smart solar is wired incorrectly, then the load is 0.1A being supplied by the smart solar, but the shunt is measuring this as coming from the battery and reducing the SOC.

( if Smart solar is wired correctly, the load is 0.2A with 0.1A coming from battery and 0.1A coming from solar)

Simon