Does it matter if my solar panels face South or "True South"?

Deep Patel

Good information here, lets just hope when pointing the panels 194 degrees (true south) there are nothing shading the area.

-Deep Patel
http://www.gogreensolar.com

doug Whillans

Good Morning my magnetic declination in the Toronto,Ontario Canada area is 10 degrees 20′ west if magnetic south is 180 which way and how far do I move to find true south

David Llorens

So you would subtract about 10 degrees from your compass so that true south is around 170 Doug.

http://geomag.nrcan.gc.ca/apps/mdcal_e.php?Year=2008&Month=9&Day=11&Lat=43&Min=39&LatSign=1&Long=79&Min2=23&LongSign=-1&Submit=Calculate+magnetic+declination&CityIndex=247

Charlie

The answers are a bit misleading. For Example #1 in California, You would point the compass at 194 degrees but orient your panels at the S that is still fixed on the compass.
Or you could point the needle North-South and face the panels at 166 degrees on the compass.

Kevin

Hey Guys, You are all technically correct in the abstract yet more considerations must be made. If your area is typically foggy or cloudy in the morning, you are better off facing the panels slightly W of S to maximize gain during the afternoon. Likewise with shading, which you want to avoid at all costs, but if you have some WxSW trees and clear skies in the morning, you are better off facing the panels E of S. Get an experienced local installer to properly evaluate your particular site.

Mike Wilhoit

Gentlemen,

Are there any figures on power loss as you move away from true south. My house is about 12 degrees west of true south. How bad does this hurt me.

Thanks,
Mike

Tor a.k.a. "Solar Fred"

Hey, Mike.

It’s not going to hurt you all that much. You’re going to lose a little bit of power production, but that’s not a big deal. Your roof does NOT have to face exactly South, true or not. Plenty of systems get installed on Western systems and Eastern and South Eastern etc. North, now that’s a problem.

Assuming you’ve got good subsidies, net metering, and good sun, it’s still going to be very cost effective for you. Being a few degrees off South will just mean that it will take you slightly longer for payback. Perhaps 10 years and two months, for example, instead of 10 years. It will be minor.

Hope that helps.

John E Lavender

Dave,
I know it is a bit late but I have only come across your method of finding south (or North) by the sun casting a shadow of a perpendicular pole or stick. You do know that the earths axial tilt is 32.26 degrees and if you were to pick out a nice tall perpendicular (‘Vertical’ to you) pole and every day, at high noon, place a stone (or some other suitable object) at the end of the poles shadow, at the end of a year you would have enscribed an oval of stones (or some other suitable objects) on the ground.
This is because twice a year (once in late March and another in late September)
the axial tilt would make the shadow towards the west in march and to the east in September. These are the Equinox, Vernal in March and Autumnal in September. So the right(and only)time to use your pole to align your solar panels
is when the Earths axis is perpendicular to to the Earths orbit around the Sun
and this only happens twice every year
on either 21st of June or December the 21st. These are the only time the shadows point North

RassleD

Guys, I just checked the NOAA site

http://www.ngdc.noaa.gov/geomagmodels/struts/calcDeclination

and found
Declination = 14° 16′ E changing by 0° 6′ W/year W/year for San Francisco.
It would appear to me that you subtract
this number from the magnetic north reading
to get true north because the needle is
pointing to the right of what they are calling
MN or magnetic north.

Lets say we were looking for 150 degrees.
Well, would we not really be looking for
150 – 14° 16′ or about 136 degrees?