Highest Production generated on cold Sunny days

[mgdean]

I have noticed my system puts outs some serious Kilowatts on cold sunny days. The most I have ever seen was yesterday, 7.7kw on a 6.24kw system. it was 16F with 20mph SW wind (-1 wind chill) with a handful of clouds. That's 123% of capacity, just wanted to see if others see this increase in capacity when you have below zero wind chill.

 

[Zapper77]

I'm lucky to see 90%

 

[Zapper77]

What panels and SCC are you using? Tilt, elevation (above sea level)?

 

[robby]

9,65Kw today from 10kw of panels.
That was with temps in the 70s.

 

[StuartV]

I've got 2 x JA panels. They're rated at 385W each, but I have seen them produce as much as 848W on a good day! Was well chuffed with that ?

My other 2 panels however, Trina, 340W each, max I've seen out of them was about 640W.

 

[Finca Life]

We often get 100% capacity from our 4.2kw panels but never more.

 

[timselectric]

Perfect solar production weather.
Cold and sunny.

 

[DougfromdaUP]

Here in the snowy far north of Michigan, my 10,140 watts (26 390 watt jolywood bifacials) put out 11,972 a couple of days ago. I have them vertical now to shed snow and they get quite a boost from reflections off the snow in front of them.
I regularly exceed the rated capacity in the winter, but never in the summer.

 

[peakbagger]

My 14 year old Evergreen panels will still exceed the panels ratings on my pole mount with adjustable angle in winter. The combination needs to be fresh snow on ground, no clouds, some wind and the colder the better. I also gain some early morning and late afternoon generation as I do have hardwoods to my southeast and southwest that are not leafed out yet. Generally, I get the highest production with a dome of high pressure over the area . The bummer is that up in northern NH, even though it is the Solstice today, I need to leave my panel angle at winter angle as I could still get snowstorms for a month or so and want to avoid excess snow loading. I still have snow pack so the angle is not a major issue but once it burns off in few weeks I notice the drop. I usually do not raise the panel angle until mid April.

I have one of the DC solar trailers that I modified to fixed panels that are oriented for maximum summer production and its definitely cranking out the watts despite a high angle as the sun angle rises. I do need to rake the snow off on occasion and run my snowblower in front of the panels so that the snow sliding off does not build up too high. Note the solar hot water panels on the roof definitely have some issues with snow build up sliding off. I burn wood to heat the hot water in winter so it is not a major issue.

 

[RCinFLA]

Spring is a good time for maximum solar production. Sun is getting higher in sky (welcome to Spring equinox today), and temp is still low so PV panel voltage will be higher.

Air mass index is how much atmosphere the sunlight has to go through. The lower the peak solar noon sun angle above horizon the more atmospheric attenuation. Air mass index of '1' is sun directly overhead. At silicon PV wavelengths, there is about 1300 watts per square meter above atmosphere and you get about 300 watts per square meter loss for every one thickness of atmosphere (air mass index = 1) the sunlight has to go through. Further north you are, the more atmosphere the sunlight has to go through due to low sun angle above horizon.

Humidity in the air causes more attenuation.

At lower angles, the air mass index is greater, with greater attenuation. Winter in N. hemisphere is greater attenuation due to sun being low to horizon. You also get less daylight time for each winter day.

 

[MiSh]

My pv regularly pump out 10% or more on cold, winter days too. It's fairly common. I believe that's why you're supposed to size your mppt controller to your pv using worst case scenario of coldest days you may experience at your location.

Victron's MPPT Calculator Excel Sheet

Victron provides this downloadable Excel spreadsheet tool for determining compatible MPPTs for your solar panels. You can customize it to match your situation by: Adding the specifications for your panels Exploring different panel configurations...

diysolarforum.com

 

[kid744]

5.925 kw system. Saw spikes past 6.5 kw Outside temp was ~ 30 F. Around 6 kw sustained. (spikes are only a minute or two.)
My panels are mounted on carport roof, but are bi facial, so a combination of low temperature and cloud lensing + small bifacial gain.
Kid

 

[Ekard]

I often get full rated capacity from 2x cheesy Harbor Freight panels. Clean panels, no clouds, and proper angle seem to be the ticket.

 

[Mike 134]

I see that to. 7.2KW system gets clipped at 7.6KW from the inverter when 30F or below and especially if it's partly cloudy so the panels don't get warmed from constant sunshine. Those higher numbers will last almost 2 hours either side of "solar noon"

 

[mgdean]

What panels and SCC are you using? Tilt, elevation (above sea level)?

I have 16 390w Heliene 72 Cell panels, A Sol Ark 12k, Panels are mounted on a 8/12 roof and around 1200 feet.

 

[MichaelK]

There could be a second effect besides temperature that is also boosting output. It's called "cloud lensing". I've seen this myself. Thin, wispy cirrus clouds somehow focus the light differently, resulting in short-term boosts in output. I've seen a 980W array put out 1300W once. I rushed outside to look at the clouds, and by the time I walked back, the clouds blew away and output dropped back down to about 90%, which I was used to seeing.

This happened to me once three years ago, and I haven't seen it happen again since.

 

[WindWizard]

Note the solar hot water panels on the roof definitely have some issues with snow build up sliding off. I burn wood to heat the hot water in winter so it is not a major issue.

I think you should consider a metal roof. The snow just slides off our roof in Maine.

 

[DougfromdaUP]

There could be a second effect besides temperature that is also boosting output. It's called "cloud lensing". I've seen this myself. Thin, wispy cirrus clouds somehow focus the light differently, resulting in short-term boosts in output. I've seen a 980W array put out 1300W once. I rushed outside to look at the clouds, and by the time I walked back, the clouds blew away and output dropped back down to about 90%, which I was used to seeing.

This happened to me once three years ago, and I haven't seen it happen again since.

It definitely isn't cloud lensing in my case. It's a long lasting effect, and only under super clear skies.

 

[peakbagger]

I think you should consider a metal roof. The snow just slides off our roof in Maine.

Maybe on the next house.

 

[upnorthandpersonal]

Yep - solar panel performance increases with lower temperature. That's why cooling panels is something sought after:

Review of cooling techniques used to enhance the efficiency of photovoltaic power systems - Environmental Science and Pollution Research

Photovoltaic (PV) panels are one of the most important solar energy sources used to convert the sun’s radiation falling on them into electrical power directly. Many factors affect the functioning of photovoltaic panels, including external factors and internal factors. External factors such as...

link.springer.com