Different Watt Panels - Brain Fade - Can they be run through one CC

[NotToFast]

I have a 100watt and a 220watt panel. Can I hook these up parallel on a PWM controller?

 

[sunshine_eggo]

I have a 100watt and a 220watt panel. Can I hook these up parallel on a PWM controller?

If they have Vmp values within 10% of each other, yes. Both panels must be suitable for your battery voltage.

PWM controllers must have the correct voltage panel on them, or they waste power. PWM works by shorting the panels to the battery forcing them to operate at battery voltage. Running a 17Vmp panel at 14.4V is a notable but tolerable penalty. Running a 30Vmp panel at 14.4V more than cuts the panel output in half.

It is also important that you not over-panel a PWM controller as they can't regulate current.

What battery voltage?
100W Vmp?
220W Vmp?

 

[NotToFast]

If they have Vmp values within 10% of each other, yes. Both panels must be suitable for your battery voltage.

PWM controllers must have the correct voltage panel on them, or they waste power. PWM works by shorting the panels to the battery forcing them to operate at battery voltage. Running a 17Vmp panel at 14.4V is a notable but tolerable penalty. Running a 30Vmp panel at 14.4V more than cuts the panel output in half.

It is also important that you not over-panel a PWM controller as they can't regulate current.

What battery voltage?
100W Vmp?
220W Vmp?

You would have to ask:
The 220watt is Voc=20.52, the Vmp= 17.52, The 100 watt is Voc=24.3, the Vmp= 20.4 ..
That seems weird to me that the 100watt would have a great Vmp and Voc than the 220watt?? Is that normal??

Oh and 12volts battery

 

[sunshine_eggo]

Those panels can be used together in parallel. Their Vmp is disappointingly different, but they should perform with no more than a 10% performance penalty.

More power just means physically larger. There are many variables that may contribute to differences in Vmp.

 

[Rocketman]

FYI - the above is correct.
Here is the math (it’s always good to understand the math).

When you connect panels in series - you add volts (Vmp) and use the lowest amps.

For parallel you add amps and use the lowest volts.

Your 220w panel Vmp- 17.52 the Amps (Imp) is probably 12.55.
Your 100w panel Vmp- 20.4 the Imp is probably 4.9

Volts * Amps = watts

So combined in parallel you add the amps - 12.5+4.9=17.4
And use the lowest volts 17.5
On a mppt SCC 17.4a * 17.5v = 304w

I think the PWM formula is 17.4a * 14.4v=250w.

So in the future - you may want to get a mppt charge controller. You will gain 50w.

 

[NotToFast]

Thanks, Greatly appreciate the knowledge!