Solar Array Mounting

ggunn · October 2013

Re: Solar Array Mounting

Cariboocoot wrote: »

Galvanized = zinc. PT lumber = copper. Put the two together and add a little moisture and guess what happens?

But the copper is not metallic copper, it's part of a copper compound. Is it still a problem? For example, the sodium in sodium chloride is very different from metallic sodium, especially if it comes in contact with water.

Cariboocoot · October 2013

Re: Solar Array Mounting

ggunn wrote: »

But the copper is not metallic copper, it's part of a copper compound. Is it still a problem?

That would depend on exactly what the compound is and its resulting electrolytic characteristics.

As it is you'll find the industry does have standards for connectors used with various types of PT lumber. Any place that sells it should be able to advise you on what's right for use with #1, #2, #3 (most common), #4, and #5 (marine grade). Note I said "should", not "absolutely will". :roll:

Vic · October 2013

Re: Solar Array Mounting

The last PT DF what we bought was heavily treated (for ground contact), and right on the Packing Slip was the advice on the type of fasteners to use, and spec required for HDG connectors, possibly the grade of SS required as well. This was really a Disclaimer.

In my opinion, the common PT compounds are corrosive due because they are "salts" of metals. I am not a Chemist, or much of anything else, other than opinionated, IMHO. Vic

waynefromnscanada · October 2013

Re: Solar Array Mounting

Just in case some may have missed this official alert on PT wood and fasteners etc:
http://www.oaa.on.ca/professional+resources/resources+for+architects+&+practices/pressure+treated+wood+alert

.

jcheil · October 2013

Re: Solar Array Mounting

waynefromnscanada wrote: »

Just in case some may have missed this official alert on PT wood and fasteners etc:
http://www.oaa.on.ca/professional+resources/resources+for+architects+&+practices/pressure+treated+wood+alert

.

This is interesting and may explain some of the things debated in this thread.

http://www.homedepot.com/webapp/catalog/servlet/ContentView?pn=discover_benefit_pressure_treated_wood_HT_BG_LC&storeId=10051&langId=-1&catalogId=10053#

Notice that the new "micro" process states that the lumber is more of a natural color, thus perhaps why it looks like non-PT lumber.

Also note that this new PT process leaves the PT lumber *OK* for direct contact with Aluminum.

Learn something new all the time...

mtdoc · October 2013

Re: Solar Array Mounting

As others have said, I would not use PT wood in direct contact with aluminum.

Cedar -can be a good substitute and I have used it as a bridge between PT posts and aluminum panel frames.

Cedar is softer than PT fir but can be very strong and rot resistant - but with some variation depending on the quality of the cedar. But then again I have found PT fir quality also varies and have removed PT fence posts with rotting bases after only a few years.

Fortunately good quality cedar is easy to come by here in NW WA.

westbranch · October 2013

Re: Solar Array Mounting

Cdn dollar is down

, so here is a cent and a half US more or less...

last summer we built a small external to foundation enclosed mud room.

Carpenter specifically sent me to get PT 2 x 10's that could -touch or be buried -in the ground. These are now CODE needed if the soil is within 8 inches of the bottom of the beam.

Point of note. I transported them on my small trailer, as a secured unit, by screwing on 1x4's top, bottom and sides to stop movement. I used STANDARD deck screws, the gold coloured ones... In just 2 days the coating was gone and replaced with a dark surface (that looked like bronze???) by what ever was used to treat them.

Morale: Use the Green Coloured deck screws if using PT wood... they cost 3 x as much but don't corrode...

hth

waynefromnscanada · October 2013

Re: Solar Array Mounting

westbranch wrote: »

Morale: Use the Green Coloured deck screws if using PT wood... they cost 3 x as much but don't corrode...

They have a special epoxy coating.

Coach Dad · October 2013

Re: Solar Array Mounting

Toonces wrote: »

One more quick question while we're at it. I'm not sure if I should start another thread for this though. But what is the
easiest way to find true south for panel facing?

Toonces- I don't see that anybody answered your question. So here it is...

The best way to find True-South is to use the "Solar Noon Method"
This method uses the fact that the sun is always due south at solar noon. A shadow cast by a vertical object at solar noon runs true north-south.

To determine the local time that corresponds to solar noon, find the LOCAL sunrise and sunset times. You can get the local sunrise and sunset for your location from weather.com...
Most GPS units will also give the times for sunset and sunrise -- just make sure the GPS is set to your time zone.

Solar noon is exactly half way between the sunrise and sunset time. Note that the difference between local time noon and solar noon can be quite a bit, depending on your location in the time zone, and daylight saving time.

Put a straight stick or pipe in the ground, and make sure it is plumb.
The stick will cast a shadow that points TRUE-NORTH at Solar Noon... True-South is the exact opposite of True-North.
Spray the shadow with a can or spray paint or just take a compass reading.
Good luck...

Blackcherry04 · October 2013

Re: Solar Array Mounting

Or you can use the Sun Calculator, drill down to your property on the satellite or map and put in what ever date you want. Move the time bar at the top.

http://suncalc.net/#/38.2527,-85.7585,10/2011.02.27/22:14

vtmaps · October 2013

Re: Solar Array Mounting

Coach Dad wrote: »

To determine the local time that corresponds to solar noon, find the LOCAL sunrise and sunset times. You can get the local sunrise and sunset for your location from weather.com...
Most GPS units will also give the times for sunset and sunrise -- just make sure the GPS is set to your time zone.

Solar noon is exactly half way between the sunrise and sunset time. Note that the difference between local time noon and solar noon can be quite a bit, depending on your location in the time zone, and daylight saving time.

Blackcherry04 wrote: »

Or you can use the Sun Calculator, drill down to your property on the satellite or map and put in what ever date you want. Move the time bar at the top.
http://suncalc.net/#/38.2527,-85.7585,10/2011.02.27/22:14

or try: http://www.solar-noon.com/

--vtMaps

Dave Angelini · October 2013

Re: Solar Array Mounting

One of the best things about a dual axis tracker in winter is that is will go flat during very cloudy winter skies. This will help quite a bit if you can live in that limited amount of harvest. The linear axis tracker that I have been using for folks the last 2 years is kind of the best of dual axis and the lower cost of having the array spread out over 50 feet of ground on 5 poles. The one in the picture below shows a 4,300 watt half way populated on a hill. It tracks 45 degrees on each side of flat,sAttachment not found.
sheds snow well, and does not require a ladder. You do miss out on some of the azimuth tracking of a single axis at the days extremes. With lower solar cost this is not an issue as this design does get you the hours of power a fixed array misses. This the key to running a heat pump offgrid or long well water pumping hours.

niel · October 2013

Re: Solar Array Mounting

actually coach dad i did answer his question on post 11.

Coach Dad · October 2013

Re: Solar Array Mounting

niel wrote: »

actually coach dad i did answer his question on post 11.

Niel.... You are right.. I read through it when I saw "some use a compass"... Sorry about that.

zoneblue · October 2013

Re: Solar Array Mounting

Dave Sparks wrote: »

The one in the picture below shows a 4,300 watt half way populated on a hill. It tracks 45 degrees on each side of flat,sAttachment not found.

Does that main rail faces south, and it tilts seasonally, or east west, and tilts daily? Which gives better output?

ggunn · October 2013

Re: Solar Array Mounting

Dave Sparks wrote: »

One of the best things about a dual axis tracker in winter is that is will go flat during very cloudy winter skies. This will help quite a bit if you can live in that limited amount of harvest. The linear axis tracker that I have been using for folks the last 2 years is kind of the best of dual axis and the lower cost of having the array spread out over 50 feet of ground on 5 poles. The one in the picture below shows a 4,300 watt half way populated on a hill. It tracks 45 degrees on each side of flat,sAttachment not found.
sheds snow well, and does not require a ladder. You do miss out on some of the azimuth tracking of a single axis at the days extremes. With lower solar cost this is not an issue as this design does get you the hours of power a fixed array misses. This the key to running a heat pump offgrid or long well water pumping hours.

That's a single axis tracker. Elevation and azimuth => dual axis, elevation only => single axis.

BB. · October 2013

Re: Solar Array Mounting

I have seen that (or similar) system at a local 2 year college... As I remember, the rail is east/west with the panels facing south.

http://us.sunpowercorp.com/commercial/success-stories/education/?relType=SP_Content_C&relID=1293430121819

As a guess, it looks like the tracker is this unit:

http://us.sunpowercorp.com/commercial/products-services/solar-trackers/T0/

-Bill

I should add that the 1 axis array is at De Anza College (not Foothill--the first link references both).

Dave Angelini · October 2013

Re: Solar Array Mounting

Actually it is not a single axis! It is called horizontal axis tracking. The panels track east to west as you would expect. The difference here is the array goes horizontal for the time that the sun is overhead as a dual axis. This function is great during really cloudy weather (or for full power in the sun) as there is alot of energy in the clouds. To capture it best, you need to be flat. This is why it is a combination of a dual axis, a single axis, and something more and yet something less. About a 25% power gain over a days time and yet the long hours of full power operation that an offgrid application may require. A really usefull tool for snow country and high mountain applications. Nice simple 24Vdc motor and aluminum welding from array technology.

Bill you are mostly right though, it is a utility application that works really well for offgrid. The torque rail is mounted north/south though. This is one that you could homebrew if you had some welding talent. You do not need to be as careful as Array technology is with the engineering of a pole mount.
They once told me their pole mount AZ125 had 3 failures in 800 units. All of them were wheel bearings that they purchased that were marked wrong.

BB. wrote: »

I have seen that (or similar) system at a local 2 year college... As I remember, the rail is east/west with the panels facing south.

http://us.sunpowercorp.com/commercial/success-stories/education/?relType=SP_Content_C&relID=1293430121819

As a guess, it looks like the tracker is this unit:

http://us.sunpowercorp.com/commercial/products-services/solar-trackers/T0/

-Bill

I should add that the 1 axis array is at De Anza College (not Foothill--the first link references both).

ggunn · October 2013

Re: Solar Array Mounting

Dave Sparks wrote: »

Actually it is not a single axis! It is called horizontal axis tracking. The panels track east to west as you would expect. The difference here is the array goes horizontal for the time that the sun is overhead as a dual axis. This function is great during really cloudy weather (or for full power in the sun) as there is alot of energy in the clouds. To capture it best, you need to be flat. This is why it is a combination of a dual axis, a single axis, and something more and yet something less. About a 25% power gain over a days time and yet the long hours of full power operation that an offgrid application may require. A really usefull tool for snow country and high mountain applications. Nice simple 24Vdc motor and aluminum welding from array technology.

I know how it works, but it is a single axis tracker. The geometry of the system is that the modules rotate in a single plane of rotation, i.e. about a single axis; that's what the term means. In this case the plane is vertical (the axis is, as you say, horizontal), but it's a single plane. Go to PVWatts and it's a single axis tracker with a tilt of zero degrees; if you tilt the axis of rotation off horizontal to the south you get even more production, and in general the higher the latitude the more difference it makes.

Dave Angelini · October 2013

Re: Solar Array Mounting

You could use PV watts for a ballpark but it really is not the same. My single axis array will move 250 degrees east/west or so on the summer solstice. it will never point up flat at the noon sky like a dual axis. The horizontal linear axis tracker will point flat. I really like this as it gives you most of the hours of a single axis, and yet really nice noon production for big loads such as water pumping a deep well. You are right about tilting the axis slightly as it gives you the later hours in summer when you may need more cooling. Hours of usable power is more of the way I think about this for offgrid. The term production is more of a grid term that is secondary to an offgrid home as we very rarely use it all.

This is mostly all from the designers by the way, I just did the beta testing a few years back. The one in the picture is the one that Bill here (BB) from the forum helped me find fire code info for the in-house sprinkler system. We put up half of the array to build the house and will add the rest later. That is another nice aspect to this unit as you can add on later. This is not recommended on a pole mount. Really nice US technology.

ggunn wrote: »

I know how it works, but it is a single axis tracker. The geometry of the system is that the modules rotate in a single plane of rotation, i.e. about a single axis; that's what the term means. In this case the plane is vertical (the axis is, as you say, horizontal), but it's a single plane. Go to PVWatts and it's a single axis tracker with a tilt of zero degrees; if you tilt the axis of rotation off horizontal to the south you get even more production, and in general the higher the latitude the more difference it makes.

westbranch · October 2013

Re: Solar Array Mounting

Dave, I like the idea and simplicity. Great when you have somewhat wide open space, and few shadows.
For the one you pictured, does it use the 3 ph 1.5 Hp listed or a smaller motor?
It would work for us in summer but little winter benefit with only 4 hrs of sun contacting the PV's, max .
Spring and Fall would be a try and see as the sun goes behind a 2000 ft ridge to our West at ~5 pm by the fall equinox, after that time of day, it is cloud reflected light.

Toonces · October 2013

Re: Solar Array Mounting

Thanks guys, you gave some great info! I will send some pics of my project when I get a little further. Btw I'm a carpenter/general contractor and I'm not sure if anyone mentioned this but, the Simpson strong-tie company had to change its formula for galvanizing its products to be compatible with the newer copper lumber treatment. Be careful that the hardware you buy hasn't been sitting on shelf somewhere too long or it might be the old galvanizing formula. "zzz" or "triple z" was used to denote the new galv formula last I looked.

waynefromnscanada · October 2013

Re: Solar Array Mounting

Toonces wrote: »

Thanks guys, you gave some great info! I will send some pics of my project when I get a little further. Btw I'm a carpenter/general contractor and I'm not sure if anyone mentioned this but, the Simpson strong-tie company had to change its formula for galvanizing its products to be compatible with the newer copper lumber treatment. Be careful that the hardware you buy hasn't been sitting on shelf somewhere too long or it might be the old galvanizing formula. "zzz" or "triple z" was used to denote the new galv formula last I looked.

More good info! Thanks a lot "Toonces" for sharing. Much appreciated.

ggunn · October 2013

Re: Solar Array Mounting

Dave Sparks wrote: »

You could use PV watts for a ballpark but it really is not the same. My single axis array will move 250 degrees east/west or so on the summer solstice. it will never point up flat at the noon sky like a dual axis. The horizontal linear axis tracker will point flat. I really like this as it gives you most of the hours of a single axis...

It IS a single axis tracker. That the axis is horizontal does not make it something else. PVWatts is mainly for GT systems because GT systems always export the full capacity of the system, but it can model a horizontal single axis tracker just fine.

From a production standpoint there is no advantage to pointing your modules straight up if the sun is not directly overhead.

Dave Angelini · October 2013

Re: Solar Array Mounting

And this would not be the first time that engineers disagree on the basics.

ggunn wrote: »

It IS a single axis tracker. That the axis is horizontal does not make it something else. PVWatts is mainly for GT systems because GT systems always export the full capacity of the system, but it can model a horizontal single axis tracker just fine.

From a production standpoint there is no advantage to pointing your modules straight up if the sun is not directly overhead.

ggunn · October 2013

Re: Solar Array Mounting

Dave Sparks wrote: »

And this would not be the first time that engineers disagree on the basics.

What is there to disagree on? If a line normal to the surface of the modules stays in a plane as the modules move, by definition it's a single axis tracker no matter how that plane is oriented. In the one you showed, that plane is vertical. That's nothing special; a lot of single axis trackers are oriented that way. They would produce more if the axis were tilted, but that would make them more expensive to build.

The highest producing single axis tracker would be one whose axial tilt would change every day to match the apparent changing angle of the ecliptic plane to the horizontal at the point of the array, but then it wouldn't really be a single axis tracker any more, would it?

I do not blame you for putting the best face possible on equipment that you are selling, but if you claim to your customers that this is anything other than a horizontally oriented single axis tracker, you are misleading them.

zoneblue · October 2013

Re: Solar Array Mounting

Yeah id like to see some output curves. It seems to me that if youre at 45 lat, with that NS rotation axis being level, at midday your angle of incidence is going to be 45 deg. How can that help mid day production? Itll help with morning and afternoon production sure which is cool. However whats the payback time? Everyone i talk to says fixed at latitude is the most cost effective, with PV so cheap. But never seen any numbers to verify.

ggunn · October 2013

Re: Solar Array Mounting

zoneblue wrote: »

Yeah id like to see some output curves. It seems to me that if youre at 45 lat, with that NS rotation axis being level, at midday your angle of incidence is going to be 45 deg. How can that help mid day production? Itll help with morning and afternoon production sure which is cool. However whats the payback time? Everyone i talk to says fixed at latitude is the most cost effective, with PV so cheap. But never seen any numbers to verify.

It depends on the time of year, but yes, it will always be less than optimal at solar noon. At the spring and fall equinoxes the angle of incidence will be 45 degrees at solar noon, but on the winter solstice it will be 21.5 degrees. The best it will ever be is on the summer solstice - 68.5 degrees. The higher the latitude, though, the more viable tracking is, generally speaking. In the summer months at high latitude, a fixed array at latitude tilt will be lit from the back for a significant part of the day.

The point I think he was trying to make is that on a cloudy day the array will orient itself flat (pointing straight up), which will maximize the collection of diffuse light. I suppose that could be correct, but the production under those conditions is small compared to the collection from direct sunlight on a sunny day. My quibble with him is over his implication that this makes it something other than a single axis tracker, which it doesn't.

shoalbilly · October 2013

Re: Solar Array Mounting

Weather underground will tell you Solar Noon for your location.
After you choose your location, Click on "More Astronomy" below the Station select and moon label
at the top right. Top right of Astronomy page gives this for the current day and location
Astronomy
Oct. 16, 2013 Rise Solar Noon Set
Actual Time 7:36 AM CDT 1:18 PM CDT 7:00 PM CDT

This is my first post, have been reading here for 11 months and have learned tons !
Found this recently and wanted to share.
Shoalbilly
Mark Mallett

Dave Angelini · October 2013

Re: Solar Array Mounting

Ah Mr Gunn, Why quibble? Life is too short! I will just say that yes it is a single axis tracker. Yes it behaves differently than Array technology single axis trackers which are the only ones I use because of reliability. The algorithm is different and it is better in my testing for what I need offgrid. Harvest of power is second to hours of usable power! The HZLA is a nice blend of a Wattsun dual and single axis. That is my point. Not just engineering theory but tested.

I see that you have changed you opinion on pointing an array up in diffuse light. It is not only the pointing up that helps harvest but the problems a "regular" single axis has with getting lost in low light. This can hurt as the array is not getting the full incident light. The numbers are small compared to full sun but many offgrid folks learn to reduce power consumption on these days.

You could always just use fixed arrays at different orientations and go outside and adjust them. Most of the people I know would rather pay a hundred thousand dollars or more and bring in the utility at that point. There are many power curves on the array technology site, they do not show the hours of power very well. No one really has done that except offgrid folks who know it from experience.

Solar Array Mounting

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