Mono or Poly solar panels for winter output?

[Gordon Bland]

We live in a caravan with flat roof mounted panels in New Zealand so we need the most output from what we've got as we can't just add more panels. Over the winter months the sun only averages 10-20 degrees above the horizon so huge offset to flat panels. Also New Zealand means 'land of the long white cloud' so we have plenty of cloudy days to contend with.

I'm just about to replace my panels and I've always used mono. However on cloudy days their output really drops off. I've come across a couple of site comments that really have me considering poly instead? In summer we have oodles of power so it's winter performance that is crucial to save me from having to run the backup generator often. As the mono or poly panels are now available for the same output, size and price then I could easily use either.

https://solarfeeds.com/can-solar-panels-work-without-sunlight/#Do_Solar_Panels_Work_on_Cloudy_Days
Polycrystalline solar panels are more efficient than amorphous panels and can work well in changeable weather conditions. Though the level of efficiency of these panels much lower than polycrystalline panels.

Monocrystalline solar panels are the most efficient ones. They can generate maximum energy from minimal space and have the longest life expectancy. However, these panels do not perform well in cloudy or shady conditions.

http://thatpowerguy.nz/solar/how-solar-panels-work
Monocrystalline Solar Cells
Disadvantages
If your panels are at risk of shading or you commonly have cloudy skies, monocrystalline panels are also more sensitive to obstruction than polycrystalline panels.

Polycrystalline Solar Cell
Advantages
They also tend to perform better if you have issues, or may have issues, with panel shading or often experience cloudy skies.

https://www.solarpaneltalk.com/forum/off-grid-solar/off-grid-solar-panel-systems/19073-mono-vs-poly-in-low-light
Right now I am using a 245w mono side by side with a 250w poly with identical controllers/ set ups and the poly is winning in bright and lower light. The poly doesn't get as high of Voc but it also doesn't drop as fast when the light dims a bit. The mono will drop from 17a output on a MPPT controller to 2.38a as soon as the light clouds come in and will be asleep when the poly is still kicking out 4 and 5 amps when you can barely tell where the sun is. This is in a RV off grid where those 5 amps can keep us off the generator if we behave. With three panels producing 15a total, we might cut back on the microwave usage.

I also saw this on my original set of panels, a Canadian solar 220w mono and a Schott 230w poly three years ago. The difference then was the mono is considerable smaller than the poly. The 245w and 250w above have the same footprint.

Now according to all the "test" (advertising) , this is wrong and really I'm just a guy in his drive with meters, controllers and such. The thing is I am not advertizing anything, just report what I see side by side in a off grid RV type situation.

So does anyone has have any real world data using both mono or poly?
These comments have me thinking that for wintry and/or cloudy conditions that I should I switch to poly to get a more consistent output?

[Dacian Todea]

There is basically zero difference between mono and poly crystalline panels.

If both panels have the same rating they will perform exactly the same.

Poly is wining because is a 250W panel but it will be a marginal win over the 245W mono. If you see any significant difference they you have shade or other problems affecting one of the panels.

They should perform with no more than 5% difference between them in all conditions.

[Paul Barrette]

100 watts panels but this is a poly vs mono showdown

https://www.youtube.com/watch?v=dZ_jrSAk-DU