Can I combine these two old 50w panels in series with a new 390w panel for a 12v battery?

[gilatm]

I have two old 50W panels:
50w
imp 2.72A
VMP 18.39V
Isc 2.91A
Voc 22.50V

and would like to add a 390w panel that I can pick up locally,
390w
Imp 9.73A
VMP 40.6V
Isc 10.17A
Voc 48.2V

to combine to make a 490w system. They would connect to a EPEVER 40A MPPT Solar Charge Controller 12V/24V Auto Working Max.PV 150V Solar Panel Charge Regulator Tracer BN Series Negative Ground Solar Controller, to feed a 12v Lithium battery (overkill 4s 120a BMS, and a 1500w inverter). I'm assuming the charge controller can convert the voltages to 12v.

So, I'm thinking this will work? Any thoughts?
Thanks! Gil

 

[JeepDaddy]

Work, yes.

490W, no.

In series, you will be limited by your lowest current panel, so think more like 50 + 50 + 118 (40.6x2.91) or 218 watts total.
In parallel, you will be limited by your lowest voltage panel, so think more like 50 + 50 + 179 (18.39x9.73) or 279 watts total.
Or you could series the 50W and parallel to the 390w, run the same calculations and do somewhere around 458W.

 

[gilatm]

Great! Thanks! The last option was what I had in mind, I think I will go with that.

 

[gilatm]

Am I correct that if I would add a third 50W panel, in series, I would end up with about 500w? (brining the 50w panels up to 55v, so I get the entire 390w from the 390w panel, and the 2.9a from the 50w panels are multiplied by the 40.6v of the large panel, minus some loss, to gain me 112w).
Gil

 

[GSXR1000]

Great! Thanks! The last option was what I had in mind, I think I will go with that.

why not put your 50w on a separate SCC like this...

 

[gilatm]

I'm uncertain what I would benefit from having them go through a separate charge controller. I'll have to think on that.

I have more recently realized I could double up on my 390w panel, and exclude the two 50w from the system - save them for camping perhaps. I didn't realize I could "over panel", and increase my output on most every day (they would be sitting flat on top of a small shed that has some shade at times, so they would seldom be fully realized. My controller says it can handle 1500w of panel when oversized, but will use only the equivalent of 520w. 780w of panels (2x390) seems like a reasonable choice.

Gil

 

[DIYSteve]

As mentioned above, you would benefit so much better adding the two 50w panels on a cheap PWM solar controller than you would adding them in seriesbthen parallel with the other. Add another 1-3 of the larger panels to the EPEVER 40a controller for a decent system

 

[pollenface]

I agree.

 

[meetyg]

Maybe another solution (I'm asking, not suggesting) :
How about connecting the 50w panels in series, parallel with the 390w panel, but put a blocking diode on the 50w string. Wouldn't that minimize the voltage drop of the whole setup?

 

[JWLV]

To GSXR1000, when you say to add a cheap PWM SCC to the 50W panels, how is it connected to the rest of the system?
Does that mean the cheap SCC output goes to the input of the EPEVER 40A controller? Or connect the cheap SCC directly to the battery which means its parallel with the EPEVER 40A?

I've seen talk about adding another SCC to mismatched panels. But they never discuss how or where the cheap SCC is to be connected. I hope someone can explain it.

 

[GSXR1000]

To GSXR1000, when you say to add a cheap PWM SCC to the 50W panels, how is it connected to the rest of the system?
Does that mean the cheap SCC output goes to the input of the EPEVER 40A controller? Or connect the cheap SCC directly to the battery which means its parallel with the EPEVER 40A?

I've seen talk about adding another SCC to mismatched panels. But they never discuss how or where the cheap SCC is to be connected. I hope someone can explain it.

both SCC output connects strait to the battery... they work independently