Solar Panel Winter Performance

[FresnoBound]

Hi there, just a quick question on how your RV solar panels are holding up during the winter.  I've been reading online how they continue to work during the winter months.  Albeit at a reduced capacity. 

It's not the panels that change, it's the insolation.  Using Fresno, CA as an example, 200w of flatmounted panel on MPPT will average:


Solar wattage 200

Month Daily Wh Avg
Jan  369
Feb  595
Mar  860
Apr 1114
May 1278
Jun 1426 <- party in the USA
Jul 1394
Aug 1267
Sep 1037
Oct  746
Nov  534
Dec  355 <- austerity
Average 915
The above projection based on PVwatts

Is it true the continue to generate power if the daylight is permanently overcast?  

Yes, the figures above include 30 years of weather and irradience data.

Do you have to cut back on an appliance or two during winter months??

I oversized my array to ensure sufficient harvest for necessities year 'round.   In December I have to back off all-electric cooking and burn some propane.  Not a bad thing since it helps warm the van.

Wow, thanks for this frater secessus.  This is exactly what I’ve been looking for.  Excellent data.  Did you gather it yourself? 

And, your clear markation of ‘party in the USA’ and  ‘austerity’ months are classic.  I got a giggle from that one.  It’s great to get some numbers and clear data on winter performance.  Most of the info out there is pretty non-descript. Like this one - using rv solar panels in winter.

I figured there’d be some scaling back in the winter.  To be expected to be fair.  But as you’ve pointed out, no harm burning a little gas to help keep the cabin warm.  This way you can kill two birds with one stone.

@rvpopeye, yes I have a pretty basic setup at the minute.  But with seasons starting to change I’ve noticed a dip already.  Looks like there will be significantly less power as the days shorten and blue skies give way to overcast.  I’ll see how it goes over the winter and make some adjustments as necessary.  Fridge and cooker will most likely be dropped.