3 serial panel

[frankz66]

Hello everyone, being a beginner I wanted to ask:

I have 3 180 watt 12v panels ( voc 23.1) configured in series.

My system can always be defined as 12v since each panel is 12v or does it always remain defined as a 12v system but in series for a total voc of 70 volts?

 

[FilterGuy]

My system can always be defined as 12v since each panel is 12v or does it always remain defined as a 12v system but in series for a total voc of 70 volts?

The system voltage is defined by the battery voltage, not the panel voltage.

Panel labels pf 12V or 24V came from a time when people hooked panels directly to the battery or used MPPT controllers where it was best to match the battery voltage and the panel voltage.

With a modern MPPT controller, the battery voltage and panel voltage is almost completely independent. With MPPT controllers the only linkage between Battery voltage and panel voltage is that the input typically has to be higher than the battery voltage.....

 

[frankz66]

The system voltage is defined by the battery voltage, not the panel voltage.

Panel labels pf 12V or 24V came from a time when people hooked panels directly to the battery or used MPPT controllers where it was best to match the battery voltage and the panel voltage.

With a modern MPPT controller, the battery voltage and panel voltage is almost completely independent. With MPPT controllers the only linkage between Battery voltage and panel voltage is that the input typically has to be higher than the battery voltage.....

Thanks for the information, it was just simple curiosity about how to understand or better define the plant. So I use an epever 4210AN and if I'm not mistaken it can handle batteries up to 42 volts. Therefore it is correct to say that if I change my accumulation I will put it in series up to 48 volts, from what you write, can the system be defined as 48 volts? Example : 2 12v panels in parallel , one mpttt controller and 4 batteries in series from 12volts ?

 

[rodrick]

Don’t go over 24 volt battery bank I have 3 of those units and they are 12 or 24 volt battery bank only
they automatically detect battery voltage and setup for that voltage that is why you must hook up the battery first before solar they will not do 48 volt batteries

 

[Rednecktek]

Thanks for the information, it was just simple curiosity about how to understand or better define the plant. So I use an epever 4210AN and if I'm not mistaken it can handle batteries up to 42 volts. Therefore it is correct to say that if I change my accumulation I will put it in series up to 48 volts, from what you write, can the system be defined as 48 volts? Example : 2 12v panels in parallel , one mpttt controller and 4 batteries in series from 12volts ?

Ok, I think you've got one crucial thing backwards. A "system" is refered by it's nominal system voltage of the battery bank.

The whole definition of "12v panel" or "24v panel" comes from marketing where a "12v panel" can provide enough voltage on its own to charge a "12v system" but not enough on its own to charge a "24v or 48v system". The 12v panels will often put out 18ish volts at full bore, the 24v panels can do 30ish. Now, you could put 2 of the "12v" panels in series to feed a 24v battery via PWM, but by the time you're getting into a system that big you're already into the range where an MPPT controller is worth the expense.

In the world of charge controllers you've got your basic PWM and your smarter MPPT controllers. In basic terms, a PWM controller lets as much voltage through as the battery can take and just clips the rest off as waste. If you've got 18v of panel trying to pump 14v into your battery, that's 4v just being clipped off. If you were to put one of the 30v panels on the same battery, it would clip 16v off as waste which is a huge waste of panel. Up to about 3-400w of panels on a 12v system, a PWM will work fine. Larger than that and a MPPT starts to be a good investment.

So, to get around this we have MPPT controllers that take the incoming higher voltage and transform that into lower voltage but higher amperage out to the batteries. Much more efficient use of the panel.

Once you start stringing multiple panels together in series that voltage gets really high which is good for running long wires, but can't be used directly to the battery.

So, that 4210 you've got is good for 40a of current to your battery, and up to 100v of incoming voltage, or VoC. It can only work at 12v or 24v nominal battery voltage, so there's no getting these to feed a 48v battery system. But, that means you can use 40a × 12v =480 watts of panel. The hard, and I mean DO-NOT-CROSS-THIS-LINE thing to pay attention to is the VoC of the panels and the MaxPV Input of the charge controller. Solar panels create more voltage when cold so 80% is a good number to aim for, or about 80v VoC in your case. Your 3 panels are 70v so still a healthy voltage.

Did that make sense?

 

[frankz66]

Ok, I think you've got one crucial thing backwards. A "system" is refered by it's nominal system voltage of the battery bank.

The whole definition of "12v panel" or "24v panel" comes from marketing where a "12v panel" can provide enough voltage on its own to charge a "12v system" but not enough on its own to charge a "24v or 48v system". The 12v panels will often put out 18ish volts at full bore, the 24v panels can do 30ish. Now, you could put 2 of the "12v" panels in series to feed a 24v battery via PWM, but by the time you're getting into a system that big you're already into the range where an MPPT controller is worth the expense.

In the world of charge controllers you've got your basic PWM and your smarter MPPT controllers. In basic terms, a PWM controller lets as much voltage through as the battery can take and just clips the rest off as waste. If you've got 18v of panel trying to pump 14v into your battery, that's 4v just being clipped off. If you were to put one of the 30v panels on the same battery, it would clip 16v off as waste which is a huge waste of panel. Up to about 3-400w of panels on a 12v system, a PWM will work fine. Larger than that and a MPPT starts to be a good investment.

So, to get around this we have MPPT controllers that take the incoming higher voltage and transform that into lower voltage but higher amperage out to the batteries. Much more efficient use of the panel.

Once you start stringing multiple panels together in series that voltage gets really high which is good for running long wires, but can't be used directly to the battery.

So, that 4210 you've got is good for 40a of current to your battery, and up to 100v of incoming voltage, or VoC. It can only work at 12v or 24v nominal battery voltage, so there's no getting these to feed a 48v battery system. But, that means you can use 40a × 12v =480 watts of panel. The hard, and I mean DO-NOT-CROSS-THIS-LINE thing to pay attention to is the VoC of the panels and the MaxPV Input of the charge controller. Solar panels create more voltage when cold so 80% is a good number to aim for, or about 80v VoC in your case. Your 3 panels are 70v so still a healthy voltage.

Did that make sense?

Thanks, I already know this, I was just trying to understand the definition of system 12 24 36 48, which I seem to understand that it refers to batteries. Thank you for your opinion.

 

[Rednecktek]

Yup. It's an odd terminology thing.