Bi-Facials, installation height matters just as much as the angle of the dangle

eXodus

Solar Addict
Maybe I'm an optimist, but it was interesting to see they were getting gains at only 7cm. With the prices we are seeing for the et solar 410w panels, I thinks it's still worth it for 5-10%.
depends where you put them. Ground mount also has the disadvantage of dirt getting on the panels - which reduces yield pretty fast. The higher you are up the cleaner the panels stay. I think ground mount solar farms on bare undisturbed land should be outlawed as long not every parking lot has solar carport on them. Digging up natural land to place solar panel is not very sustainable.

use already disturbed land - don't use more land.
 

NwCali

Solar Addict
or just use them as regular panels, I got them OOOOOOOOOBER cheap.... and it's not worth the hassle or the risk of damage to mess around with them...
Well, from what I have read the degradation is much less on Bifacials... So, if price point is close and longevity is something you value.

I live in a Unique place where I have steep terrain, lots of sun (compared to being more west/towards the ocean), but Coastal influence keeps the temps down (Any further East and the Temps go up fast in the summer).

Hopefully in the next month I'll finally have 10 panels up and running and can post how it all turns out here.
 

NwCali

Solar Addict
If anyone reads this I'd like some input on this....

If I decrease the angle to raise the lower edge height will I gain or loose output?

During summer I expect to have more solar that I'll need by a good bit. In the winter time the sun will be at a low angle, which in my mind would increase the amount of sun reflected. So I am planning on going with a higher angle for better winter output, which will decrease my height above the ground....to what I suspect will be around 2 feet.

Maybe in the next week I'll have enough completed where I can play around with it all to see the effects in real time, but winter (low sun angle) would tell me more.

Any thoughts/input?
 

Jennifer

Electricity kills, think twice before acting.
Ok booooyes n goyles... I think I decided where to put my bi-facials....... I'm in the process of building a 12' x 24' shed... and was just going to use the fancy new roof for rainwater catchment, which I still can.... and every morning when I get the laser shot of reflection in the back of my head through the window I kept debating it... but finally gave in.... the 1st shot below shows me looking west at the shed roof, all brand spanky new shiny corrugated...... ALL MORNING this roof gets an absolute flogging from the sun... the second shot shows me looking east, ALL AFTERNOON till the burning ball of hell fire goes down this west exposure gets a flogging as well....

I just checked my bi's.... I can easily put a 2 high by 3 long = 6 on each side in a landscape config, into a separate charge controller for each side, and while my lower edge won't be the meter above the ground/surface, I think having these mirrors behind them should light them up pretty good and make up for it..... and the run up to my toy hauler in the background wont' be far at all. It'll all happen in this shed, by run I mean split phase, (not solar PV voltage) this will be the power center for the lower part of the property where I plan to put in some cabins/rv spots maybe at some point. Then on the roof of the toy hauler I'll load it up with flat non bi's, putting these on there would be a waste, putting them on this mirror finish should kick donkey and give me crack of dawn till dusk generation... The compass shot shows the N/S layout of the shed, not ideal but pretty good none the less.

370 watts each, X 6 per side... and I'll still have a few left for another shed.... YAY

I'll probably go S-5 rib mounts and some Iron Ridge rails, (unless all you wiser than I have suggestions, I'm totally open). They won’t be flat,I’ll throw some tilt on them to get as much reflectivity on the back side as I can.


Note, directions of the white arrows means nothing, I was just over excited and drew too many white arrows... it's not indicative of the rays from the burning ball of hell in the sky.

What'ya'all reckon?

Jen
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Jennifer

Electricity kills, think twice before acting.
If I decrease the angle to raise the lower edge height will I gain or loose output?
Unless you have them mounted on a pivot point in the middle on both sides, lowering the angle isn't going to automatically raise the lower edge or am I missing something about physics?
 

NwCali

Solar Addict
I now have my panels up where they go and realize the hill/terrain/trees are pretty varied and I'm not really worried about the output on the backside/versus angle. I'll get what I get.

In choosing my panels locations I choose the area that will get the most sunlight. Its not flat or easy access. We had to rig a pulley/cable (think zip line in reverse) system up to get them in over many obstacles. But there ALL in and none were broken!
 

HRTKD

Boondocker
Ok booooyes n goyles... I think I decided where to put my bi-facials....... I'm in the process of building a 12' x 24' shed... and was just going to use the fancy new roof for rainwater catchment, which I still can....

I didn't realize you got enough rain in that area to justify a catchment system. My buddy that lives in Dolan Springs gets almost no rain.
 

Jennifer

Electricity kills, think twice before acting.
I didn't realize you got enough rain in that area to justify a catchment system. My buddy that lives in Dolan Springs gets almost no rain.
Yea we do... problem is it all comes in about 10 minutes, the entire years worth.. .LOL... I built a HUGE ground based rain roof and then signed a contract for a well as this trommel drinks water like nobody's business.

A8826DBC-A779-41DD-85BA-A6F0FA867346_1_105_c.jpeg
 

NwCali

Solar Addict
I moved to the coast to avoid the water problems, even in our "drought" year we had over 80 inches of rain. :)
 

Jennifer

Electricity kills, think twice before acting.
I moved to the coast to avoid the water problems, even in our "drought" year we had over 80 inches of rain. :)
I hear ya, I'm from British Columbia and Washington State, living in AZ has given me an entirely new appreciation for water.

PS: I'm ok hijacking the thread to talk about water.. I started the thread... LOL... open discussion....
 

Jennifer

Electricity kills, think twice before acting.
For those interested... my idea for the rain roof came from another Canadian now living in Arizona, Darren...... check out his videos.... (difference is, he's not running a water thirsty trommel processing 30 yards an hour)
 

svetz

Works in theory! Practice? That's something else
...I'm ok hijacking the thread to talk about water.. I started the thread... LOL... open discussion....
You don't have to hijack your own thread, you can start a new one... and folks interested in water might participate whereas they might not visit for a thread saying it's about bifacials. Just saying, hate to see that whole sub-audience lose out ;-) (a moderator can split it for you if you like, just indicate what you want for the new thread title, what forum, and which posts you want moved by "reporting" the first post to move).
 

NwCali

Solar Addict
PS: I'm ok hijacking the thread to talk about water.. I started the thread... LOL... open discussion....
I suspect many of us doing DIY solar also have rain catchment systems..... I do. I even plan on including the panel runnoff going to a water tank to water a garden during the dry/grow season. Why spend the Juice to pump when nature does it for you (if you plan it properly)?
 

Tuckles

Solar Enthusiast
depends where you put them. Ground mount also has the disadvantage of dirt getting on the panels - which reduces yield pretty fast. The higher you are up the cleaner the panels stay. I think ground mount solar farms on bare undisturbed land should be outlawed as long not every parking lot has solar carport on them. Digging up natural land to place solar panel is not very sustainable.

use already disturbed land - don't use more land.
I agree! Here in Florida FP&L is tearing out entire citrus groves and covering them with solar fields wasting some of the best farm land in the country. One of their people I was working with told me they really don't care about solar, the Fed's forced them to do it before they would allow them to do some other things they wanted to do, buying the electric company in Hawaii was one of them.
 

svetz

Works in theory! Practice? That's something else
So what's your current thinking regarding bifacial panels? I didn't really get what you doing in #24:
...my lower edge won't be the meter above the ground/surface, I think having these mirrors behind them should light them up pretty good...

Using the bi's as the roof of a carport/patio, or something totally different? Where are the mirrors?
Can you sketch what you're envisioning for us?

Sounds like you're going non-bi for the toy hauler roof. But not sure what you're doing with the bi panels. Doubt you're mounting them "less than a meter" above the shed roof (from the other thread the hurricane-like winds would blow the shed over)?

It'll be interesting to see how mirrors do compared to something like crushed white rock or white painted ground.
Ordinary mirrors don't reflect as much light (~80-90%) as some aluminum/mylar coatings (~95%) - mylar is probably cheaper, lighter, and less durable. They might also be hard to keep clean.
 
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Jennifer

Electricity kills, think twice before acting.
I didn't really get what you doing in #24:
Forgive my lack of artistic ability, am on a conference call and pretending to contribute.... when I said mirrors, I was referring to the brand new sheets of corrugated roof tin that reflect the sun.... ala "The 1st shot below shows me looking west at the shed roof, all brand spanky new shiny corrugated...... ALL MORNING this roof gets an absolute flogging from the sun... the second shot shows me looking east, ALL AFTERNOON till the burning ball of hell fire goes down this west exposure gets a flogging as well...."

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svetz

Works in theory! Practice? That's something else
Oh duh!
300px-Paris_Tuileries_Garden_Facepalm_statue.jpg

Perfect sense now that you've spelled it out for me ;-)

How high are you thinking you'll put the panels above the roof and what's going above the S-5s (i.e., what are using to get the elevation above the S5)?
I'll probably go S-5 rib mounts and some Iron Ridge rails, (unless all you wiser than I have suggestions, I'm totally open). They won’t be flat,I’ll throw some tilt on them to get as much reflectivity on the back side as I can.
The S-5 Rib mounts you linked look tough, but the metal gauge of the roof usually isn't all that thick, you might also want something like we use here for "hurricane strapping" to help keep the roof on.

Wind forces on elevated sources are huge. My panels are flat and I take a fairly big hit from hit from it. But the wind forces with even a few inches elevation would be the equivalent of a herd of elephants on my roof (several tons). But, codes here are for 180 mph winds.

I started from the basics document, but if you look at example 2 it's for 90 mph winds with panels parallel to the roof which is the best case to minimize wind forces:

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When you work through the math they come up with:

1625698677179.png
So, for 90 mph, that's an uplift pressure of about 23 psf and downward pressure of about 15 psf for zone 2 (explanation of zones), as you can see they get a whole lot worse near the top and corners.

The LG Neon2 bifacials are 18.44 ft², so 12 of them would be ~222 ft² (if my calculator is right). so 222 x 15 = 3320 lbs downward force and 5110 lbs uplift. Have a steeper roof? More force. Add tilt, more force.

Hope that helps!
 

Jennifer

Electricity kills, think twice before acting.
Oh duh!
300px-Paris_Tuileries_Garden_Facepalm_statue.jpg

Perfect sense now that you've spelled it out for me ;-)
Thaaaaaat's ok... it's a good thing you're cute... LOL...

Thanks for the comments, will read and reply tomorrow, my Malinois is about to take my arm off if I don't give her some play time, she's not a fan of the extra marital affair I'm having with Victron.

Jen
 
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