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Solar Panel Tilt Test. What are your angles for 38 Degrees North Latitude?

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Onehand

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For June and December?

I have used 5 different calculators and no 2 agree. Only reason I ask is I have devised a tilting rack where I can change the angle on 8 groups of 4 panels to anything needed.

So far, June ranges from 11 to 18 degrees, December from 46 to 66 degrees, with autumn/spring ranging from 31 to 42.

I am trying to find the winter/summer stop points.

Curious to see what everyone has to say?

ETA; Even using the latitude formula where you multiply your latitude by .9 and add/subtract for summer/winter comes out to 11 summer and 62 winter.
 
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I don't know how to determine quantitatively, but for a while now my thinking is to go a few degrees less than perpendicular to the sun at noon. The reason being, not every day is sunny. When you have cloudy days it may be better to have your panels at a less steep angle in order to catch light from more of the cloud-diffused sky. Think about the extreme case - if you live at the North Pole and have your panel mounted vertically at 90 degrees at the summer solstice, on a cloudy day your panel cannot "see" the other half of the lit sky, so your production is approximately half of what it would be had it been lying horizontally.
 
I use the following and adjust once a month.
  • January: 43.4°
  • February: 38.4°
  • March: 33.4°
  • April: 28.4°
  • May: 23.4°
  • June: 18.4°
  • July: 23.4°
  • August: 28.4°
  • September: 33.4°
  • October: 38.4°
  • November: 43.4°
  • December: 48.4°
I get it from this site

footprinthero.com

Peak Sun Hours Calculator (with Map) - Footprint Hero

Calculate peak sunlight hours for your location (city, address, or zip code) with our free peak sun hours calculator.
footprinthero.com footprinthero.com

I am at this map coordinates


44° 36′ 59″ N, 70° 14′ 37″ W
44.616389, -70.243611
 
I am at 41 N , and I purposely set up to optimize my winter tilt at 36 degrees (off vertical, 54 degrees off horizontal), as I get more than enough in the summer.
 
Why not just place a speed square on the face of the solar panel, then adjust the angle of the panel until there is no shadow? Now you are perpendicular to the sun. How can you get any better then that? If your panel only moves on 1 axis then you will have to perform this at the appropriate time of day.
 
At 38.7 latitude, I do 15 in summer, 30 in spring/fall, and 45 in winter (from horizontal) because it is easy to remember.
and it’s close enough.
 
green mountain boys said:
Why not just place a speed square on the face of the solar panel, then adjust the angle of the panel until there is no shadow? Now you are perpendicular to the sun. How can you get any better then that? If your panel only moves on 1 axis then you will have to perform this at the appropriate time of day.
Click to expand...
Ya, I have more accurate tools than that. I was just looking for a hard stop on the racks for summer/winter and was wondering how many different answers I would get from all these obviously flawed, or variable calculators out there.
 
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Onehand said:
Ya, I have more accurate tools than that. I was just looking for a hard stop on the racks for summer/winter and was wondering how many different answers I would get from all these obviously flawed, or variable calculators out there.
Click to expand...
The calculators work to an extent, the programs used to develop them may have had some flaws. While they say they used real data, I have yet to determine if they actually used different angles to collect data at the same time/location or if the calculator is based upon data from a fixed array, then computed off that set of data. Most likely it is computed off a single set of data. One thing I have noticed is how quickly in the morning I can get close to full output with panels tilted to 60 degrees in winter. If the calculation is based upon a fixed array, then it could explain why some of us see greater daily yield than what was projected by a calculator.
 
I was just looking for a hard stops for summer and winter for this rack design. I need to machine material and wanted to keep material removal to a minimum for strength.

After taking averages from all the calculators, guess I will just cut it for the extremes of 12 and 66 degrees and find out where the happy spots are after it's up and running. Have a feeling it would be best between 16 and 60 for 38deg N lat.
 
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Angle and orientation are a lot more involved than just picking one angle (although often that is all we have to play with).

It is fairly easy to lookup the elevation of the noon time sun for the various months at your location. But that only optimizes for noon on a sunny day. If your weather patterns include AM clouds or PM clouds most days, or other such factors you may well do best aiming your panels a bit off due South (if that is an option) where you are. Similarly, significant amounts of energy can be gained pre and post noon elevation in many locations; that is to say aiming for noon sun may not give the best cumulative totals.

I found the following site to have a good discussion of the factors involved (no connection to the site other than as a visitor)

 
Onehand said:
Ya, I have more accurate tools than that. I was just looking for a hard stop on the racks for summer/winter and was wondering how many different answers I would get from all these obviously flawed, or variable calculators out there.
Click to expand...
How about a 24" or 48" square? That would increase the accuracy. Why wouldn't this get you to less than 1 degree of accuracy? How accurate do you want to be? What will you gain? I am not trying to argue. I just don't see why this solution is not just as good as sitting down with a pencil and paper, assuming you have an array already built you can easily adjust. If you have not yet built the array then sure, do the math.
I once took a class in college in which we used aerial photographs taken so they were partially overlapping and perpendicular to the ground. When viewed from directly above with a stereoscope we could calculate the height of any object based on the length of the shadow on the ground. This technology was used extensively in WWII and in the post war years. I would have to refresh my memory if I had to do it all these years later. I just fail to see the value in it when there are simple solutions.
 
I am building the adjustable racking for these 32 panels for around 1500. The mounts are aiming due south, not the perfect 10 degrees west of due south but the best I can get without additional calamity.

The quarterly/monthly tilting adjustments will be made using angle gauges. I was just looking for dead winter/summer stops for the manufacturing process, so I could tilt and lock and be good so I wouldn't have to drag a speed square into it to align.

Thanks for your input.
 
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Here is an equation from a study of Stanford University for best solar panel tilt angle:

Best angle（North hemisphere）=1.3793 + Φ(1.2011 + Φ(-0.014404 + Φ0.000080509))
Best angle（South hemisphere）=-0.41657 + Φ(1.4216 + Φ(0.024051 + Φ0.00021828))
（Φ = latitude of where you live）

Looks complicated but easy to calculate ? you could have a try for reference.

Here is the link: https://web.stanford.edu/group/efmh/jacobson/Articles/I/TiltAngles.pdf
 
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