Solar Panel "Tilt" site, Which one is Correct?

[Onehand]

Maybe I am just burned out with all this but I cant see how 40 degrees from horizontal and 35 degrees from vertical come out to the same angle for winter in my area.

Way I see it, in my area, a 40 degree tilt down from horizontal for January, doesn't line up with a 35 degree tilt up from vertical for the same month. Looks like a 5 degree difference. Splitting hairs here? Or am I missing something

Check out your area and tell me if I am messed up here?

Solar Panel Tilt Angle Calculator - Footprint Hero

Calculate the best tilt angle for your solar panels based on your location (address, city, or zip code) with our free solar panel tilt angle calculator.

footprinthero.com

Solar Angle Calculator

The solar angle calculator tells you by location the optimum angle to get the best out of your system.

www.solarelectricityhandbook.com

 

[Culchee]

Maybe I am just burned out with all this but I cant see how 40 degrees from horizontal and 35 degrees from vertical come out to the same angle for winter in my area.

Way I see it, in my area, a 40 degree tilt down from horizontal for January, doesn't line up with a 35 degree tilt up from vertical for the same month. Looks like a 5 degree difference. Splitting hairs here? Or am I missing something

Check out your area and tell me if I am messed up here?

Solar Panel Tilt Angle Calculator - Footprint Hero

Calculate the best tilt angle for your solar panels based on your location (address, city, or zip code) with our free solar panel tilt angle calculator.

footprinthero.com

Solar Angle Calculator

The solar angle calculator tells you by location the optimum angle to get the best out of your system.

www.solarelectricityhandbook.com

I’m not understanding the vertical tilt...

 

[Onehand]

Starting with a panel vertical and tilting the bottom up. Ck the sites out, read instructions.

 

[Culchee]

Starting with a panel vertical and tilting the bottom up. Ck the sites out, read instructions.

Thanks...

 

[Culchee]

I’m not sure why they can’t stick with either the vertical or the horizontal as the base line...I get the summer v winter thing .. but why not just one base line..

 

[justgary]

The first site agrees with my calculations for my location. The second one does not. It should be 90 degrees minus the first one.

 

[Hogheavenfarm]

Sadly, there is no "standard" for tilt angle, you need to know whether the basis is "tilt from horizontal" or "tilt from vertical". Most calculators I see are based on tilt from horizontal, I think because solar "began" being used in more southern latitudes first, where panels often just lay flay on the ground or on a roof, now up in the far north, panel tilts are almost always much steeper, so it makes sense to measure the tilt from vertical in those cases.

 

[justgary]

But the second site doesn't agree with the first, and the first looks correct to me.

 

[timselectric]

All adjustments should be measured from vertizontal.