Old and new panels

[Aphers]

I've been reading up about mixing different sizes and specs of panels and getting fairly confused.
I've already got a 100w 12v panel, but want to upgrade to a total of around 800w. I'd also add a new MPPT.
If I buy more 12v panels and want to run everything through the same SCC, should I buy the exact same model of panel as I already have- or does it not really matter so long as they are nominally 12v?

I could also not worry about my existing panel and buy a couple of big 32v 300w panels, cheap as chips, but the cost savings evaporate when I try to get them delivered. Lots of smaller 12v panels works out exactly the same cost to me, and I would get more shade tolerance, but it also seems to work out a bit bulkier and heavier overall. Not a deal breaker.

Any thoughts appreciated- I'd like to get my order in ASAP since they'd be coming from Germany to the UK and after the end of this year Brexit will very likely complicate that sort of transaction.

 

[snoobler]

The Imp range of all panels in a series string needs to be very close. All panels will be limited by the lowest current panel.

The Voc and Vmp range of all panels in parallel need to have substantial overlap.

You could have XSYP configuration where all the parallel strings are the same working voltage, but each string could have substantially different currents, and the array would essentially perform to specification.

Consider a 330W 24V panel. You could put a 2S string of 100W panels in parallel with it, and they would have the potential to produce 530W. The 330W panel has a Vmp of around 36V while the 100W have a Vmp around 18V, so 2X18V = 36V - they match.

Easy/lazy mode is just order the same panel from the same manufacturer, but with a little number crunching, one can make odd arrays work sometimes, particularly if one is okay with sacrificing 5% performance to notably increase the size of the array (by well more than 5%).

If all you have is a single panel, then that's probably not worth fretting about. If it's cheaper to get 2-4 big panels, set the 100W aside.

 

[Aphers]

The Voc and Vmp range of all panels in parallel need to have substantial overlap.

Thanks as ever Snooblers
My 100w panel has 22.6VOC and 19.35VMP
The 130w panels from the same supplier are 21.74VOC and 18.00VMP.

Would you say these figures are close enough for me not to worry about it?
I hear what you say about getting rid of the 100w panel I already have to simplify things- however that's the largest panel that will fit in that particular spot.

But I am swaying towards the larger, higher voltage panels. A couple of 320w panels gets me the power I need at far less total weight, which is a consideration since I'm mounting them fairly high up on a boat.

 

[snoobler]

Yes. It's one of those ~5% situations though. Your MPPT will work somewhere in the range of 18-19.35V, so they'll be a little off for both of them, but still pretty close to their Vmp. Thus you might be losing about 5% of your max power from the array, but your total wattage gains are much higher compared to not having the extra 100W panel.