With a mix of 1x300W, 2x200W and 1x100W panels -- how best to configure?

[MegaMosquito]

These panels are all 12V with different wattages (and physical sizes and shapes) in order to maximize the wattage I can squeeze onto my RV roof. My friend called this playing Tetris with the various panels I could find from a large number of vendors. I haven't bought any yet, but this 800W collection looks good to me. The 300W panel is 10BB technology and the others are all 9BB.

I read Will Prowse's awesome book, but I am still unclear about what is the best strategy for managing an odd collection of panels like this. I would love to pump up the voltage by connecting some panels in series, but I think that's not good for this miss-matched wattages. So I have been thinking of connecting all 4 in parallel with a single 80Amp MPPT controller. Is that a good plan? Or would 2 (lower capacity) controllers (or perhaps more than 2?) be better? Or is this whole plan crazy?

For additional context, I am currently planning two 460Ah LiFePO4 batteries (specifically the ones from LiTime). I plan to charge them from the solar of course, but also from "shore" power at campsites, and from the RV's diesel generator when needed when we boondock.

What do you experts think? Should I use this odd collection of miss-matched panels to maximize wattage? If not, I'd love to see read your suggestions about how to proceed.

Thanks!

 

[Rocketman]

In order to figure this out we need from each panel:
Voc
Vmp
Isc

What solar charge controller are you thinking about? What are its specs?

When you combine different electrical specs of panels there is a penalty- how big or little of a penalty depends on the electrical specs of the panels. I have seen systems that had a very small penalty- and I have typed to people that it was better to leave a panel off their system - it all depends…

Also how hard would it be to run another set of wires down from the roof? Also, can you get more of any of those panels?

When you add panels in series to volts add and you use the lowest amps. When you add in parallel the amps add and you use the lowest volts.

 

[chrisski]

What do you experts think? Should I use this odd collection of miss-matched panels to maximize wattage? If not, I'd love to see read your suggestions about how to proceed.

Don’t use the panels that are mismatched.

To see why, look in my signature block for mismatched panels and run the math. The math won’t lie.

The worst thing I did was design my first Rv build with a panel I got on a good deal. Cost me a lot of time and money.

 

[Mattb4]

If the voltage is pretty close (within 2-3vDC) Parallel the 100w and 300w than wire in series to the 2 -200w also wired in parallel. This will limit you to either a 12vDC or 24vDC setup. In essence you create 2-400w panels in series.

 

[MegaMosquito]

Wow! 3 replies already. I love this forum!! Great points, @Rocketman. And I read your Mixing/Matching link, @chrisski. And thank you too, @Mattb4. Given this, I reconsidered and played some more rooftop Tetris. I can place 4 *identical* 12V, 200W panels on my roof (with some difficulty -- one panel must overlap my shower skylight by 4 inches, but that's well worth it for the advantages of identical panels and moving up to 48V. Thanks you so, so much everyone!

 

[Rocketman]

Good choice…