best charging configuration for dull days

[Arosfa]

Hi,
I have a question regarding the best voltage --12 or 24-- for charging batteries on dull days. It occurs to me that batteries are charged with current for any given voltage and one should optimise for current supply. My system is currently 24 volt with panels and batteries in series but all parts of the system, chargers and inverter, are happy with either 12 or 24 volts. Would it be better to go to a 12 volt setup to double the current or would it make no difference? I understand that this would also double the load current, but that is within one's control to an extent. Weather isn't. Rain every day for the last 4 months in Wales has made off-grid living a challenge to say the least.

 

[timselectric]

24v is more efficient than 12v. But watts are watts, no matter what the voltage is. Switching to 12v, would give you more amps. But the watts wouldn't be any better.

 

[sunshine_eggo]

You can't get blood from a turnip.

If you have shit conditions, you get shit performance at all voltages. You might be able to find a way to squeak out another 1-2% of goody by swapping things around, but that's on a relative basis, i.e., lets say you have a 1000W array that is only getting 100W due to poor conditions. I'm NOT saying you'll get another 10-20W from a 1000W array, I'm saying you'll get another 1-2W from the 100W of performance you're getting.

Now... this I have to know.

Please show me an inverter that can accept either 12 or 24VDC input. I've never seen anything like that.

 

[Arosfa]

You can't get blood from a turnip.

If you have shit conditions, you get shit performance at all voltages. You might be able to find a way to squeak out another 1-2% of goody by swapping things around, but that's on a relative basis, i.e., lets say you have a 1000W array that is only getting 100W due to poor conditions. I'm NOT saying you'll get another 10-20W from a 1000W array, I'm saying you'll get another 1-2W from the 100W of performance you're getting.

Now... this I have to know.

Please show me an inverter that can accept either 12 or 24VDC input. I've never seen anything like that.

https://www.sunshinesolar.co.uk/media/ecom/prodpdf/VP2000.pdf

 

[sunshine_eggo]

https://www.sunshinesolar.co.uk/media/ecom/prodpdf/VP2000.pdf

Nope. Those are three different units. Go to their website and see how you must select units that operate on a single DC voltage.

https://www.sunshinesolar.co.uk/Category/PowerInverters

You're stuck with whatever voltage your inverter operates at.

 

[Arosfa]

24v is more efficient than 12v. But watts are watts, no matter what the voltage is. Switching to 12v, would give you more amps. But the watts wouldn't be any better.

Understood, but given the same wattage would a battery charge faster with higher current or is power the deciding factor. I suppose I could do the experiment and report back

 

[sunshine_eggo]

Understood, but given the same wattage would a battery charge faster with higher current or is power the deciding factor. I suppose I could do the experiment and report back

You can't use that inverter at 12V.

 

[pollenface]

Best charging configuration for dull days is more solar panels.

 

[Arosfa]

Nope. Those are three different units. Go to their website and see how you must select units that operate on a single DC voltage.

https://www.sunshinesolar.co.uk/Category/PowerInverters

You're stuck with whatever voltage your inverter operates at.

Which makes my question moot, doesn't it. Although I would consider having another inverter, a winter one, if that made the difference.

 

[Arosfa]

Hi,
I have a question regarding the best voltage --12 or 24-- for charging batteries on dull days. It occurs to me that batteries are charged with current for any given voltage and one should optimise for current supply. My system is currently 24 volt with panels and batteries in series but all parts of the system, chargers and inverter, are happy with either 12 or 24 volts. Would it be better to go to a 12 volt setup to double the current or would it make no difference? I understand that this would also double the load current, but that is within one's control to an extent. Weather isn't. Rain every day for the last 4 months in Wales has made off-grid living a challenge to say the least.

Thanks for all the prompt replies.

 

[timselectric]

but given the same wattage would a battery charge faster with higher current or is power the deciding factor.

Watts are Watts.

 

[Supervstech]

Higher voltage has less loss from circuit resistance...

I would think highest voltage your controller can accept will get the most watts to the battery.