Will my MPPT Controller handle this?

[swvic_matt]

Hello.

Just looking for confirmation on my assumptions below.

I have a Renogy 40A Rover Elite MPPT controller.

I currently hook a single 160W solar blanket up to it, but now I need a bit more charging power, so I'm looking at getting a second blanket.

My current blanket outputs around 18v and 7A.

I'm looking at a second blanket that outputs around 18v and 10A.

My plan is to connect the 2 blankets in series, which should give me around 36v and 7-8 A.

From the data sheet of the Renogy controller, it lists:

PV Input Voltage Range : 15V – 100V VOC

My understanding is that the Renogy device should have no problem with the 2 blankets hooked up in series.

Does that all sound correct?

Thanks for any & all help.

 

[MichaelK]

Are you reading 18V off the sticker, or is that what you are measuring with a voltmeter? There are actually two voltages, the Vmp, and the Voc. Vmp is the voltage at maximum power, or in other words, the voltage the panel can put out under load. Voc, is the open circuit voltage, or the voltage of a disconnected panel that isn't hooked up to anything.

It's the Voc that you need to worry about. If 18V is the Vmp, then most likely the Voc is somewhere around 22-24V. But, even wired in series, the Voc is likely to be only ~44-48V, so it's still far below the 100V limit.

The other thing to pay attention to is the amps. The 40A limit is the amps going OUT of the controller, not the amps coming in. So, if you have 160W X 2 panels = 320W, that 320W will get transformed down to about 26.7A at 12V. So, both the volts and the amps is lower than what your controller is good for.

Even if you wired three in series the numbers would be 72Voc and 40A, just coming in at the amp limit.

 

[swvic_matt]

Are you reading 18V off the sticker, or is that what you are measuring with a voltmeter? There are actually two voltages, the Vmp, and the Voc. Vmp is the voltage at maximum power, or in other words, the voltage the panel can put out under load. Voc, is the open circuit voltage, or the voltage of a disconnected panel that isn't hooked up to anything.

It's the Voc that you need to worry about. If 18V is the Vmp, then most likely the Voc is somewhere around 22-24V. But, even wired in series, the Voc is likely to be only ~44-48V, so it's still far below the 100V limit.

The other thing to pay attention to is the amps. The 40A limit is the amps going OUT of the controller, not the amps coming in. So, if you have 160W X 2 panels = 320W, that 320W will get transformed down to about 26.7A at 12V. So, both the volts and the amps is lower than what your controller is good for.

Even if you wired three in series the numbers would be 72Voc and 40A, just coming in at the amp limit.

Thank you MichaelK. That 18v I can't remember if it's Vmp or Voc, but I can easily measure it this weekend with my multimeter and I can work it all out then.

But either way it looks like I'm OK to put that second blanket in series.

Thank you for your help.

 

[Bud Martin]

If you have two panels in series, the current will be the lowest of the panel current spec., I.E. panel with 7A in series with the 10A panel, the result will be 7A.

 

[swvic_matt]

If you have two panels in series, the current will be the lowest of the panel current spec., I.E. panel with 7A in series with the 10A panel, the result will be 7A.

Yep, bit of ashame that. Thanks Bud. Appreciate the help.

 

[73powerstroke]

I would get 2 of the same