Combining Panels

[chrisblessing]

Greetings. I have a small camper on which I have and Eco-Worthy 160w flexible panel. The specifications are:

160W​
Max. power Current(Imp)​	9.06A​
Short circuit current(Isc)​	9.60A​
Max. power voltage (Vmp)​	17.7V​
Open circuit voltage(Voc)​	20.68V​

Needless to say, after 3 years output has degraded, so that I generally see a maximum of 45 watts and about 2.9 amps in full, overhead sun. With good exposure the panel is sufficient, but without much margin for clouds or shade. What I wonder is whether adding a 50w flexible panel for which the camper has room, might be a just-ok way to supplement the older panel. The new panel specifications are:

50W​
Max. power Current(Imp)​	2.71A​
Short circuit current(Isc)​	2.92A​
Max. power voltage (Vmp)​	18.5V​
Open circuit voltage(Voc)​	22.6V​

I understand the downsides of combining different capacity panels in series, but given the degraded performance of the original panel I estimate that combining the existing and the new panel I should have a combined output of roughly 90-100 watts and current of about 2.7 amps. My perspective is that the original 160w panel now offers about the same capacity as the new 50w panel. Does this sound anywhere near a reasonable perception?

A few things to note. First, the camper is small so I only have enough roof space to accommodate the original panel plus the additional, much smaller new panel. Secondly I can purchase the new panel for a low enough price to keep my overall investment within reason until such a time as I can upgrade the entire system. Finally, my battery is a 120Ah LiFePo4 DIY with a Rich Solar MPPT charge controller and Daly smart BMS.

I appreciate any input but ask that any responses acknowledge that I prefer not to spend more than the $80-100 I have budgeted for this this.

Thanks so much. This forum has been invaluable for me

 

[740GLE]

What’s the max VOC of the SCC?

Sounds like a series configuration. Any shading on the panels?

Have you tried cleaning the panel?

 

[Bud Martin]

That is a lot of degradation.
Have you done Voc and Isc test on the old 160W panel yet?
I sounds like you have 12V system, I would do parallel setup.

 

[chrisblessing]

That is a lot of degradation.
Have you done Voc and Isc test on the old 160W panel yet?
I sounds like you have 12V system, I would do parallel setup.

I have done the testing. To be honest the panel never delivered anything close to 160 watts. When new I was lucky to get 90-110 watts. The MPPT SCC keeps an historical record of charging so it's easy enough to see how the panel is performing and it's declining performance.

If I purchase the 50w panel I will experiment with parallel vs series. However, I still need to determine whether my scenario above makes any sense. For all intents and purposed, the existing 160w panel and the 50w panel have nearly identical profiles.