Solar Orientation

hot_rod

mounting is another option. Many of the solar controls, like the Caleffi I-solar have a function to run east and west facing panels.

Being off true solar south up to 15 degrees has a fairly small performance penality. Same for the mounting angle.

Download the free RET Screen software to run some what- if options for mounting.

hr

klaus

South orientation...

I really want to add solar to my house. After much study I'm still not exactly how I'm going to do my piping configuration to tie into my existing geo-radiant system, but that's not even my question!

My house runs NW - SE and the attached garage roof runs opposite, SW - NE. I would like to go with roof mounted panels but how do I get them facing South? Is there special mounting hardware available, or do you just have to go with what ever roof section faces closest to true South? The garage roof faces closest to South and would be most convenient for piping.

Thanks, Rich L

Jim_47

Solar Info

If your going to be doing a DIY installation, spend the time on a text book that will give all the information you will require. The one I have is "Photovoltaic Systems"
isbn978-0-8269-1287-9 . the directions you indicate of your roof, is that magnetic south or SOLAR south? I could mean a difference by up to 15 degrees!! Also you never asked about the angle from flat to elevated? The book will aid you in determining the most optimum angle. I am taking a college course this semester at the college I graduated 30 yrs ago. The course Photovoltaics!!! My intention is not to be an expert at this but to atleast be able to DIY.

Brad White_194

Oatey

had a guide pamphlet (I think it was Oatey, the folks that make flashing boots and other plumbing specialties).

Basically, from your base mounting points which Oatey among others, make. These attachment points allow a number of strut systems to be installed. From them you can angle the panels with struts to any angle you choose. Chevron patterns result sometimes and historic districts shudder, oh well...


There is also a solar pathfinder device I once had use of and may yet buy it. You can Google it (did we really need that verb??!), or Real Goods has it too. Runs about $300 so it is an investment to share. What it does, is plot your actual daily sun exposure, all day, from a given point. It identifies shadow spots and the ideal azimuth. I had to use that word today and I am done.

CC.Rob_10

racks, azimuth and elevation

An example set of racks that allow wracking:

http://sunearthinc.com/mounting_rack.htm

I'm sure there are many, many others, better and worse, but I'm familiar with these because the Empire version is on my roof. The mounting feet have two holes to lag into the rafters. If you wrack the racks to face more south, you can sister the necessary rafters so you still have two lag points. I'm sure there are other mounting systems out there that have a simpler, more elegant solution (I did not need to wrack, so didn't sister, but it is an option.)

There are some good resources for looking at the effects of orientation and elevation, such as the NREL PVWATTS system (http://rredc.nrel.gov/solar/codes_algs/PVWATTS/version2/). Granted this is for PV not thermal, but it seems like the thermal estimation software is not as far along yet. At least the freebies. But it will still give you a monthly, location-specific solar resource estimate.

As I understand it, true south is the preferred orientation, but there's a fair amount of leeway. As pointed out above, due to magnetic declination, true south is (in the NE US) ~12-15 degrees west of magnetic south. Here's a good, zip-code based declination calculator: http://www.ngdc.noaa.gov/geomagmodels/struts/calcDeclination

If you can't get true south, then facing west of south is better than east of south (as it was related to me, specifically for thermal systems). There's apparently not a huge performance hit if you are within 25 degrees or so of true south.

The elevation (tilt-up) of the panels is generally your latitude in degrees. Go more vertical for better winter performance, flatter for better summer performance.

Not comprehensive by any means, but just a few thoughts.

klaus

Thanks

Thank you for the responses.

I'm out in the country on a farm so I don't have to worry about how my neighbors like my array. However I do have a much more important person to satisfy with the finished look! My dear sweet wife's not so sure about the garage roof location (SW) as it's visible from the front of the house. We'll see how that plays out.

In my location True south and magnetic south run very close. I'll check out the info and sites given. I've checked out the solar pathfinder on their website Brad. It looks very interesting. Maybe I can talk work into buying it for future solar jobs!

Thanks again for taking the time to respond. It's all sincerely appreciated. Rich L