Summer vs winter

[metalheaddoc]

I am going into my first winter with my solar setup. I have 400W of panels. In the summer, I was getting 300-325 W in good midday sun. What can I expect for output on sunshiny winter days? To generalize the question, how much worse is winter solar production vs summer? I am in the Midwest about 39 degrees latitude.

Jason

 

[42OhmsPA]

Pvwatts.gov and suncalc.org are great resources. Have fun.

 

[Don B. Cilly]

You can probably get more due to cooler temperatures - depending on the panels' angle obviously - but for a lot less hours.
Even though, a mitigating factor of that can also be the sun's azimuth morning and evenings, if you have a south-facing array.
The sun rises and sets quite a bit to the north of east and west in summer, the opposite in winter.
-

 

[OffGridInTheCity]

I'm in Southern Oregon where we have rainy (cloudy) winters but pretty clear spring/fall and 100% clear summers. My panels are fixed at 25deg and 18deg.

In general I get 25% in dead winter (Dec/Jan) compared to spring/summer (May/Jun/July/Aug) power. However - weather (clouds) can vary. Last winter, in my 3rd December of solar I was shocked that I only got 12% of summer power (instead of 25%) due to a severe rainy month of storm after storm - couldn't believe it was so low. Some days it was <3kwh on a 13kw PV array. Overall PV production balanced out because Jan was higher than previous years but it finally got thru my rose colored glasses that solar alone can be difficult - backup plans (or 8x the number of

In any case, agree that PVWatts is a good source for estimation but remember it's based on past weather at you're location.

 

[metalheaddoc]

I’ll try those websites. Thanks.

My panels point straight south. I have them propped up about 30 degrees I think.

 

[Repro]

I am a little late to the game, but my solar array does better in winter than in summer. There are a two main reason for this I think. If I am wrong, please chime in.

My array is facing southwest. I live in the city limits, and my space constraints do not give me much freedom for panel placement. I have twelve 320W panels. The way the sun rises and sets in the summer, then winter have the biggest affect. My panels do not get good sunlight in summer until about 10:45 am due to the lay ot the land. They get good sunlight until about 4:30pm, then the angle of the sun after that gets me very low performance until the sun gets behind house tops at 7:30pm. In the winter the sun is lower in the sky and my panels get sunlight about 7:30am, and then the sun is blocked by a tree at 4:30pm.

The next factor is temperature. My panels seem to like cold temperatures a lot. I know that the colder the better to a point for solar panels. We were hit by a polar front in Pennsyvania last week with temps plumeting to 16 degrees at night and not going over 25 during the day. My panels were cranking out the juice. My panel array in its configuration does about 120V peak in summer. When it is really cold, it does 147V peak.

So it is all dependent on the setup and conditions. My array does better in winter. Go figure.

 

[Scoutmaster]

I’m running 400w of panels at my cabin and pulling in 5Watts on a cloudy day for a few hours.