Hi. 

I have two 42.3 volt open circuit and 13.2 amp short circuit panels and I have two 49.2 volt open circuit and 11.6 amp short circuit panels

Can I connect the first two in series to makeup one string and connect the second two also in series to makeup a second string and them connect the two

strings in parrallel?

Or is there a better configuration.

Thanks.

If you have low voltage mppt's then yes you could do it that way.
What are the mppt specs?

52 minutes ago, Hendrik Viljoen said:

Or is there a better configuration.

They won't really play well together, do you know the Imp and Vmp figures? Since you only have one MPPT it seems, it might be best to series one of each, a 42.3Voc + a 49.2Voc and then parallel those, but the current would be limited at most, to 11.6A per panel series string...

The VMP = 40.8v IMP =11.3A per panel on the first string and 

VMP = 36v IMP = 12.5A each on the second string.

WannabeSolarSparky.

I've got a Sunmagic 3.5kv MPPT and inverter 24volt system

14 minutes ago, Hendrik Viljoen said:

WannabeSolarSparky.

I've got a Sunmagic 3.5kv MPPT and inverter 24volt system

Can you post an image of the specs usually found on the side of the inverter?

Sure

1 hour ago, Hendrik Viljoen said:

The VMP = 40.8v IMP =11.3A per panel on the first string and 

VMP = 36v IMP = 12.5A each on the second string.

Based on this and your inverter specs, I'd say one of each in series with the 2nd type...

so 40Vmp + 36Vmp most likely giving you 11A or so, so around 800W or so and the 2nd unmatched panels also in series and paralleled up to the 1st unmatched pair, is what I would try and see what kind of power you get, then eventually you can try the 2 X 40.8Vmp in series and in parallel with that the 2 X 36Vmp panels in series, so the 1st bunch would probably get drawn down to 72V, I suspect you'd get more power from the unmatched series string... but only trial both ways will let you get actual power data...

Thanks Kalahari Meerkat. Just wanted to ensure myself that I will not damage anything.

20 minutes ago, Kalahari Meerkat said:

Based on this and your inverter specs, I'd say one of each in series with the 2nd type...

so 40Vmp + 36Vmp most likely giving you 11A or so, so around 800W or so and the 2nd unmatched panels also in series and paralleled up to the 1st unmatched pair, is what I would try and see what kind of power you get, then eventually you can try the 2 X 40.8Vmp in series and in parallel with that the 2 X 36Vmp panels in series, so the 1st bunch would probably get drawn down to 72V, I suspect you'd get more power from the unmatched series string... but only trial both ways will let you get actual power data..

I rate the 2nd option the better solution as the 1st option you will throttle the higher amp panels. 

Edited December 1, 20232 yr by Scorp007

I'd go with Option 1 as the safest. That solution will give you balanced-Voltage strings, so when you parallel them, you wouldn't be applying a reverse Voltage to the lower-Voltage string.

I don't think it's a big deal to throttle the higher-current panels. They have peak current at 12.5A vs 11.3A, so a loss of maybe 50W of peak power clipped off the top, but the question would be how often that peak would be relevant. Would have to see the current curves on the spec sheet to know for sure, but my guess is that you'd see above that mainly above 800W/m^2 irradiation, so not all the time either.