Solar and lithium

[steveswift]

Hi guys , please see attached info , (which I don’t quite understand) does my Solar appear to be working to full capacity ?
There’s 600w up there , and 220ah of lithium in batteries

I’ve been parked up for a week without charging… general power use , tv and lights , light use of microwave and kettle via inverter

Cheers

 

[G7UXG]

He has 600w would imagine 2 parallel 2 series so 4 150w panels just a guess.

If each panel was 150 watts and (say) 20 volts, that would give 300w of solar at 40 volts. They would all need to be in parallel to get 600 watts at 20 volts, and I don’t think there’s any need to have them in series to increase the voltage in a 12 volt system.

 

[funflair]

Hi thanks for all this , however , way beyond me ! So after reset I’m now getting a false reading of battery state of charge , is that right ?

No I don't think you will be a million miles out once the solar goes to float the State Of Charge should read 100% anyway, I think it might be worth posting the Battery page from your shunt and somebody who knows more than me will tell you if it's right or not but I think it should be set to sync to 100% when the batteries are full.

 

[funflair]

If each panel was 150 watts and (say) 20 volts, that would give 300w of solar at 40 volts. They would all need to be in parallel to get 600 watts at 20 volts, and I don’t think there’s any need to have them in series to increase the voltage in a 12 volt system.

Watts would still be watts it's the amps that would halve as the voltage doubles.

 

[steveswift]

If they are then you’ve probably got a high resistance connection because something is dropping the voltage.

If you can measure with a DVM between the solar controller output and the battery post and detect approximately 0.7V then that’s confirmation that you have a high resistance in your charge path.

You need to measure between the two positive connections and also between the two negative connections. The resistance (volt drop) could be in either, or both, of the charge leads.

Ian

Many thanks

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[Ditcha]

If each panel was 150 watts and (say) 20 volts, that would give 300w of solar at 40 volts. They would all need to be in parallel to get 600 watts at 20 volts, and I don’t think there’s any need to have them in series to increase the voltage in a 12 volt system.

Good read here explaining the different styles of connecting panels.

How wiring in series vs parallel affects solar array amps & volts

The amps and volts of a solar panel array can be affected by how it is wired. This blog post will teach you everything you need to know about this.

www.explorist.life

 

[Raul]

In the OP's photos, why is the solar voltage 38.7 volts? Isn't that too high? Are two panels connected in series rather than parallel?

Nothing wrong there, that’s a healthy voltage for a mppt. At 20v a mppt it’s almost wasted and it’s not far of a PWM. Better have 1.5-2 times the battery voltage at maximum power point to make a mppt work for you.
There are times with low light, when mppt will look for max power and drag the voltage down to extract every possible watt. At 20v won’t be able to do that, it has to keep it above battery voltage to function.