Confusing myself on PV voltage and it’s relevance.

[Cush]

Evening everyone. I think I am confusing myself with the PV voltage. These are the specs of a panel…

Rated Power
200W
Open Circuit Voltage
57.6V
Operating Voltage
48V
Operating Current
4.17A

Is the 48v relevant to the mppt solar controller that I need ? I could have two of these panels in parallel. Any suggestions for an SC?

TIA
Cush

 

[Lenny HB]

Yes you need a controller that can take 60v, the Victron MPPT controller come in 75 & 100v form.

 

[RogerIvy]

As Lenny says, go for 60v or more.
It’s the open circuit voltage (VOC) that you should base your sizing on. Good idea to cater for a 10% oversizing so 75v is ideal.
On a Victron MPPT it’s important to not go for a lower voltage than the VOC of your panels as you can damage the controller. It’s ok to exceed the amps as the controller will turn off and try again without damage.

 

[Nigel Crompton]

The higher the V from the panels to the controller, in relation to the battery V, the more efficient/effective the controller will be at charging your batteries.

 

[Guigsy]

Higher voltage is generally good as it means the panel will be supplying enough voltage to begin charging in dimmer conditions, and you need thinner cabling. As long as it doesn't exceed the maximum voltage of the controller. With lower voltage panels, you'd have the option to run them in series, but it probably wouldn't be wise with this model.

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[Cush]

Should have watched this first

 

[autorouter]

On a Victron MPPT it’s important to not go for a lower voltage than the VOC of your panels as you can damage the controller.

Also remember that Voc is measured at 25°C, and it rises when it's colder. It will rise quite a bit over 57.5V on a cold day if it gets full sun.

 

[Raul]

Also remember that Voc is measured at 25°C, and it rises when it's colder. It will rise quite a bit over 57.5V on a cold day if it gets full sun.

Totally agree, specially on small leisure panels with poor temperature coefficient. I have seen voltage rise at -15C as much as x1.15 VMP on domestic house panels. The VOC must of been higher at start up.