Series v Parallel panels...

[Sirtate]

I have an existing OEM setup on my Camper.
It consists of a single 165w panel (Voc=23v, Vmp=18.72v, SCC=9.49a, Imp=8.82a. 15a fuse)
wired to a 25a MPPT SCC (Pmax= 300w, Voc- 70v)

I would like to throw another panel on the roof to bump up recovery times. There is a 12v fridge running constantly and on hot days when the beer is coming out of it regularly, the system can't keep up. I have 230Ah of AGM batteries.

Because this stuff is OEM, it is ridiculously expensive, (the twin to the existing panel is $500!) I am looking elsewhere for product.

How important is it to match panels in a series array? (avoiding overvoltage going to the SCC, of course)
Does the 15a fuse in the existing panel do anything important with flow-through power?

I hear that if one panel in a series array has shade, the entire array goes down, is this true? Or, are there exceptions?
What about parallel arrays? do the panels need to be matched perfectly? Or, just voltage wise?

My education from many years ago included classes in Avionics, and as such Ohm's law isn't new to me.

My thoughts lean towards buying a random, not too big, panel and wiring it in series with the existing panel, I can find used 250w/39Voc/7a panels for under $75. (one of these in series should provide 62Voc at 15a to the SCC...(or, 53Vmp at 14a nominal)...
Would one of those get my existing panel's 15a fuse popping?
What should I look for to keep things running in a partially shaded area?

Thanks in advance...

 

[Pete7]

Sell the 165w panel and fit two x 250A panels. They are so cheap now its not worth faffing around. Two years ago we sold our 150w panel for £75 and bought a new 300w for £100, simply because we moved away from the DIY camper / boat market into house sized panels. Regrets? should have bought two and may yet because we have room. As it is we can power the fridge and a freezer now during the summer months.

 

[OffGridInTheCity]

Agree with @Pete7 - maybe better/larger panels or even 1 panel that's larger

I have an existing OEM setup on my Camper.
It consists of a single 165w panel (Voc=23v, Vmp=18.72v, SCC=9.49a, Imp=8.82a. 15a fuse)
wired to a 25a MPPT SCC (Pmax= 300w, Voc- 70v)

I would like to throw another panel on the roof to bump up recovery times. There is a 12v fridge running constantly and on hot days when the beer is coming out of it regularly, the system can't keep up. I have 230Ah of AGM batteries.

Because this stuff is OEM, it is ridiculously expensive, (the twin to the existing panel is $500!) I am looking elsewhere for product.

How important is it to match panels in a series array? (avoiding overvoltage going to the SCC, of course
Does the 15a fuse in the existing panel do anything important with flow-through power?

If put the 2nd on in series (and they are similar) the amps will remain the same as the voltage doubles. So 15a is OK. If you do 2 in parallel, it could be 17.64a - which is too high for a 15a breaker. You could use a 20a breaker instead if wiring is OK. Typically the wiring will be standard 10awg / MC4 connectors - which is good for up to 30a.

I hear that if one panel in a series array has shade, the entire array goes down, is this true? Or, are there exceptions?

Yes - one panel in shade, even 1 cell of 1 panel in shade - will drastically reduce power on the string.

For example, on my trailer I have 2s2p 300w with strings going length-wise. You'll see that 1 string as has small sliver of shade from the house - and that string is maybe 90w while the other string is 400w right now...

What about parallel arrays? do the panels need to be matched perfectly? Or, just voltage wise?

Doesn't have to be perfect and still get 95%. I've not had any trouble with slightly (1-2v) different panels especially if they are the same wattage.

My education from many years ago included classes in Avionics, and as such Ohm's law isn't new to me.

My thoughts lean towards buying a random, not too big, panel and wiring it in series with the existing panel, I can find used 250w/39Voc/7a panels for under $75. (one of these in series should provide 62Voc at 15a to the SCC...(or, 53Vmp at 14a nominal)...
Would one of those get my existing panel's 15a fuse popping?
What should I look for to keep things running in a partially shaded area?

Thanks in advance...