I had a local builder call today and ask about laying out a house. Simple 7~9 point house with some large bulkheads apparently, because it's on a pretty good slope. No problem. But he also wanted to know if I can lay out the house "with a 2° azimuth, because that what the solar panels need to be aligned to". I told him that I'm not set up to do a grid or true North layout because I don't have a solar filter for my robot (Topcon 815A) to do a sunshot, neither do I have a GPS setup. He said he's trying to get someone to "find that 2° azimuth with a Pathfinder (or some other hand-held GPS unit, I assume)". Fine by me.
But, I have a few questions for y'alls...
1: is the 2° azimuth (from 0° South azi, I'm also assuming) THAT important? The sun shifts in the sky depending on the season, so does this orientation need to be within a few arc seconds or minutes of 2°? Or would within a degree and a half (or whatever) be okay? What's the tolerance on those things?
2: I have a transit available. Could I set up a baseline and take a magnetic and then use a current localized isogonic chart and calculate said 2° azmiuth? Would that be close enough?
I'd rather not try to do the azimuth staking, but I don't mind doing the house itself. I'm just more asking IF I could do the staking using a magnetic and the charts and be close enough for some solar panels. I simply don't know, I haven't seen the panel specs.
I'm hoping someone here has done something like this.
TIA
Carl
Just a guess, but charts and a mag. Compass would probably be tighter than a handheld, especially in the hands of an ole Glenville boy.
> Just a guess, but charts and a mag. Compass would probably be tighter than a handheld, especially in the hands of an ole Glenville boy.
Thanks for the vote of confidence. I even tried to suggest another local solo LS that uses GPS, but the guy didn't seem to warm to that. We'll see if he calls back.
Actually a fixed panel should aimed at a zero degree south azimuth.
I'm getting the feeling that the builder is in a magnetic compass mode for whatever reason and the isogonic line in your area is two degrees off of actual south. Does that make sense?
With a transit you can do an equal altitude solar determination but that is more of a science fair project these days as you will probably not get enough billable time in to cover yourself. It will be a lot like observing the transit of Venus today.
> Actually a fixed panel should aimed at a zero degree south azimuth.
>
> I'm getting the feeling that the builder is in a magnetic compass mode for whatever reason and the isogonic line in your area is two degrees off of actual south. Does that make sense?
>
> With a transit you can do an equal altitude solar determination but that is more of a science fair project these days as you will probably not get enough billable time in to cover yourself. It will be a lot like observing the transit of Venus today.
This was all during a phone conversation, so I haven't see a lick of paperwork. I think doing the azimuth and house stakeout could fare fairly well. He talked about an initial stake out for footers, then a return trip for foundation nails.
What about catching another astro observation ?
I'm guessing that 2 +/-2 degrees would give minimal loss of efficiency, but you won't convince the client of that. Note that cosine(2 degrees)=0.9994, and 8 degrees is 0.990 so he's losing almost nothing. I'd check to make sure he knows which side of a north-south line he really wants his 2 degrees.
I would do a Polaris sight for azimuth. You ought to be able to get within minutes of arc using wristwatch time. Check it with the magnetic compass to be sure you didn't add when you were supposed to subtract. You'll have trouble getting confidence to a fraction of a degree magnetically, what with the possibility of local attraction (including eyeglasses or any other iron on your person) or in your tripod.
> What about catching another astro observation ?
I'm so out of practice doing one of those, I'm not sure I could do it in an economically efficient manner. I did one in college and one with my dad in WV about 25 years ago. I don't think it's worth me trying to relearn for a once every other decade sort of thing... no offense intended.
Bill-
I agree with all of that.
But the Polaris observation is up there with my equal-altitude solar observation as a billable non-starter. Client is unlikely to see the azimuth determination as costing that much, when he thinks a couple of minutes with a Pathfinder is all that will be required.
But our OP Carl needs to maintain some credibility with the client, for repeat business, etc. He is, after all, a fine surveyor and the expert to the client. My recommendation is get the old transit out, drop the compass needle, and apply the isogonic correction. It will probably beat the Pathfinder approach and the result, as you point out, will not matter much in the end.
The contractor's installation will probably be far worse.
Thank you both for your input. All of this means naught if he doesn't call back. I'd like to see the solar panel literature before I proceed.
This is at least a start. We ought to be the experts on this.
Very nice.
Thank you!
OP Carl 😉
They are generally pointed astronomic south but a few degrees either way makes no difference.
I do recall some arguments for pointing them in a direction other than true south. They are sometimes pointed south east because the batteries need charging more in the morning; or in areas that have good morning sun and the afternoons are often cloudy.
Here's my two 85 watt panels powering the PA system:
> I had a local builder call today and ask about laying out a house. Simple 7~9 point house with some large bulkheads apparently, because it's on a pretty good slope. No problem. But he also wanted to know if I can lay out the house "with a 2° azimuth, because that what the solar panels need to be aligned to". I told him that I'm not set up to do a grid or true North layout because I don't have a solar filter for my robot (Topcon 815A) to do a sunshot, neither do I have a GPS setup. He said he's trying to get someone to "find that 2° azimuth with a Pathfinder (or some other hand-held GPS unit, I assume)". Fine by me.
>
> But, I have a few questions for y'alls...
>
> 1: is the 2° azimuth (from 0° South azi, I'm also assuming) THAT important? The sun shifts in the sky depending on the season, so does this orientation need to be within a few arc seconds or minutes of 2°? Or would within a degree and a half (or whatever) be okay? What's the tolerance on those things?
>
> 2: I have a transit available. Could I set up a baseline and take a magnetic and then use a current localized isogonic chart and calculate said 2° azmiuth? Would that be close enough?
>
> I'd rather not try to do the azimuth staking, but I don't mind doing the house itself. I'm just more asking IF I could do the staking using a magnetic and the charts and be close enough for some solar panels. I simply don't know, I haven't seen the panel specs.
>
> I'm hoping someone here has done something like this.
>
> TIA
>
> Carl
Carl,
I've been looking for a good excuse to come for a visit. Pay for the gas and buy me lunch and I'll come up and do a solar observation with you. They take maybe 5 minutes. (Ten if we take our time and get 20 angles.)
I know my solar filter works because I used it tonight to view the transit of Venus. Pretty cool stuff.
Larry P
PS: You gonna be in Charleston on Friday? I'll be there doing the WV Mandatory classes.
>
> Carl,
>
> I've been looking for a good excuse to come for a visit. Pay for the gas and buy me lunch and I'll come up and do a solar observation with you. They take maybe 5 minutes. (Ten if we take our time and get 20 angles.)
Thanks Larry, again, still waiting to see if the builder calls back.
>
> I know my solar filter works because I used it tonight to view the transit of Venus. Pretty cool stuff.
Very nice.
>
> Larry P
>
> PS: You gonna be in Charleston on Friday? I'll be there doing the WV Mandatory classes.
No I won't. I need to get some hours, but that is a little tight for me. I didn't know about it. I need to buckle down and look for some. Someone in my local chapter mentioned you doing a class up here for us to get at least 8 hours, and I know you suggested a scenario like that one time. I'll toss it to the chapter officers and see if they'll contact you about arranging. I know you said your day rates were more than reasonable. If you are coming through on Thursday, hit me up, I'm a little out of the way (81 to 460 to 77 rather than 77 to 77/81 to 77 but it doesn't add too much.
Carl
I know my solar filter works because I used it tonight to view the transit of Venus. Pretty cool stuff.
We just projected it on a card tonight. Number one son (Master of Science) came over tonight and found the old first telescope I bought for him many years ago.
I hope that you enjoyed it as much as we did.
VA SPC Ortho Photos Or Google Earth Should Get You Close
Question is why an azimuth of 2°?
Why not 0°?
Paul in PA
VA SPC Ortho Photos Or Google Earth Should Get You Close
> Question is why an azimuth of 2°?
>
> Why not 0°?
>
> Paul in PA
Again, this was an over the phone conversation, straight out of the blue. I only tried to answer his questions as honestly as possible, without having seen any paperwork at all. I know more now than I did 3 hours ago, but nothing more about his reasonings. I'll let you know if my mental telepathy kicks in overnight. 😉
Perry, this is in regards to your setup, apologies to the OP for going totally off track. How big of inverter and how big of amp are you running? I have two 80W panels hooked to a pair of deep cycle marine batteries and a 600W pure sine wave inverter, I am going to attempt to run a bass, acoustic, two vocal mics and two drum mics this weekend for church in the park, plus a laptop. Will be powering through an older Yamaha board, I think it is 12 channel with a peak of 500W output. Looks like you have experience with something similar, any advice?
SHG
Shelby
> Perry, this is in regards to your setup, apologies to the OP for going totally off track. How big of inverter and how big of amp are you running? I have two 80W panels hooked to a pair of deep cycle marine batteries and a 600W pure sine wave inverter, I am going to attempt to run a bass, acoustic, two vocal mics and two drum mics this weekend for church in the park, plus a laptop. Will be powering through an older Yamaha board, I think it is 12 channel with a peak of 500W output. Looks like you have experience with something similar, any advice?
>
> SHG
I was running a behringer 2000 watt two-channel amp, and 8 channel mixer a small bass amp. While the PA amp is rated at 2000 watts, it only produces this through 2 ohm speakers. With my four 8 ohm speakers and cranked up pretty loud at an outdoor venue, the whole system was only drawing 160 watts, so you should be fine with a 600W pure sine inverter; just don't let anyone plug a fryolater into it or something like that.
I was also running a string of 4 60 watt equivalent compact flourescents for a while, but these only draw 12 watts each. Gett a Kill-a-Watt meter to test your load. they are around $25 at the box stores or online.
I'm using two 85 watt PV panels, two Tractor Supply 105 Amp-hr batteries a cheapo 1750 watt / 2500 watt peak modified sine wave inverter from china.
The fat wires at the bottom go to the two 12v batteries. and Yes, I am back-feeding the solar into the house wiring, but the house was not yet connected to the grid.