# Determining angle to put solar panels at.



## canfossi (Sep 18, 2005)

How do you know what angle to put your solar panels at when changing them throughout the year? Is there some formula or what do you do to determine the correct angle? I am at 44 deg N, Eastern Ontario. Thanks Chris


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## wy_white_wolf (Oct 14, 2004)

Our homestead (central Montana) is at 46d N. I use 3 settings 30, 45 and 60 and change on the 5ths about 45 days after the change of season. No real hard and fast rule.

I didn't realize any part of Canada was that far south.


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## greg273 (Aug 5, 2003)

According to the book "The Solar Electric House", its latitude PLUS 15deg. This sacrifices some summer gain, in exchange for winter gain. 
Most roofs with fairly good pitches, say over a 6/12, are pretty well suited for gathering solar energy. My roof, at 33degress, is my latitude MINUS 6deg, and I still get plenty of solar power.


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## SolarGary (Sep 8, 2005)

Hi,
I think that White Wolf has the normal rule of thumb -- tilt = latitude +15 for best winter collection, tilt = latitude -15 for best summer, and I suppose tilt = latitude for around the equinoxes.
All of these end up with the sun pointing nearly perpendicular to the panel in the area around noon. 

If the panels are near the ground, and they have a snow field in front of them, vertical will actually do best in the winter because you pick up the reflection off the snow.

If you want to see the numbers, you can either:
Download this calculator:
http://www.builditsolar.com/Tools/RadOnCol/radoncol.htm
and calculate for your state, and look at the table for a town near you.

Or, download the NREL Redbook, which has the numbers for the three tilts mentioned above:
http://rredc.nrel.gov/solar/pubs/redbook/
Just download the one for the nearest town.

If you want to get a good gut feel for why the angles turn out this way, download a sunchart for your area here:
http://solardat.uoregon.edu/SunChartProgram.html

One thing you are going to find is that radiation on the panel does not change fast with tilt, so you don't need to be right on.

Gary


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## canfossi (Sep 18, 2005)

I am just north of lake Ontario by about 50 kms, other parts of Ontario are even further south than 44 deg N. My solar panel is on a pole, thanks for advice. Chris


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## gimpy (Sep 18, 2007)

If there is any feasible way of making them adjustable it will help considerably, if not, then set them for when you are going to need the electric the most, which will likely be either winter or summer depending upon if you need more help with cooling or heating, using electric. The big mistake that a lot of people do is gauging the panels for average use, whereas if you are off grid you need to gauge them for maximal use or else you will have blackouts at peak usage


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## Ole Man Legrand (Nov 15, 2003)

My solar panels are set for max heat in the summer because in the winter I heat the water with wood. In the summer I don't fire the wood water stove,the solar takes care of it in the summer..


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## offGridNorthern (Jan 1, 2006)

wy_white_wolf said:


> I didn't realize any part of Canada was that far south.


The most sothern part of Ontario (just east of Windsor, across from Detroit) is in line with northern California. It is a very large country -- both east/west and north/south.


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