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Author Topic: Blasphemy..... Solar power.  (Read 120177 times)

BruceM

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Re: Blasphemy..... Solar power.
« Reply #120 on: March 17, 2017, 06:07:13 PM »
Panel angle depends on your latitude, and you would normally optimize panel angle for the sun angle at your month with the greatest heating degree days.
Close counts.  If you are using polycarbonate glazing, you should also be trying to minimize stagnation time through the summer.

Casey, you are further north than I thought at 21 degrees of latitude.  If your goal is water heating alone,  your optimum panel angle varies between 45 degrees in on 1 January, to 27 degrees (from flat) at the end of June. 

For those farther north, you have to consider that winter optimum angle is steeper than the noon angle; take a look at your mid morning to mid afternoon optimum angles too.  Vertical isn't bad for winter gain in the mainland US, and can easily be in shade during most of the day in summer.

You can play around yourself using the calculator here:
https://www.esrl.noaa.gov/gmd/grad/solcalc/azel.html

LowGear

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Re: Blasphemy..... Solar power.
« Reply #121 on: March 18, 2017, 05:03:14 PM »
Easy site.  Seattle is at 47.5 degrees latitude.  Then I tried this site.  http://aa.usno.navy.mil/data/docs/AltAz.php which reports that the Sun is about 65 degrees to the surface of the earth at the Summer solstice.

The 65 degrees to the surface is what I find interesting.  This tells me that the optimal angle of the collectors would be 25 degrees as the complement for 90 degrees or perpendicular to the Sun.  Of course this is optimal for one day and starts to decay as the days accumulate before or after solstice.  On equinox the Sun is about 43 degrees so 47 degrees would provide the perpendicular relationship to the Sun.  I've decided to not worry about collection very much during the Fall and Winter months of the year.  Hence optimal collection angle for the Spring and Summer, without adjusting the angle, would be about 35 - 36 degrees.  http://learnframing.com/angle-calculator-slope-degrees/  suggests a 9/12 slope to achieve this attitude.

I feel like I'm missing something?

Casey

NPR Tipper/Dump Truck
Kubota BX 2230
Witte BD Generator
SunnyBoy 6000 + SolarWorld 245

BruceM

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Re: Blasphemy..... Solar power.
« Reply #122 on: March 18, 2017, 07:35:19 PM »
I think you got it well sorted out for your intended use.  Think about the middle angle for the  morning to afternoon for all the months.  Check the boundary months as well.  For winter, more vertical helps full day collection, for summer, more horizontal.  Close counts.

buickanddeere

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Re: Blasphemy..... Solar power.
« Reply #123 on: March 19, 2017, 06:37:24 PM »
  I kept track of the output of two sets of 10Kw grid tied systems on my road. One is a tracker and the other is fixed. approx 44.5 degree latitude.  Almost exactly  the tracker made 18,000Kw hr per year and the fixed 12,000Kw hr.

BruceM

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Re: Blasphemy..... Solar power.
« Reply #124 on: March 19, 2017, 08:36:49 PM »
That seems about right, B&D.  Now that PV panels are pretty cheap no one in the right mind would do a PV tracker except as a fun hobby project.  The cost of the tracer exceeds the cost of adding more fixed panels, which then don't have any ongoing maintenance cost.   

In the winter in the northern hemisphere off grid homes need energy the most,  tracking is pointless, since the total useful range in azimuth is so small.




LowGear

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Re: Blasphemy..... Solar power.
« Reply #125 on: March 20, 2017, 08:51:23 AM »
Wow.  A 10 KW system that tracks.  That's around 40 panels isn't it?  Can you get any photos?

Casey
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buickanddeere

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Re: Blasphemy..... Solar power.
« Reply #126 on: March 20, 2017, 03:36:49 PM »
Wow.  A 10 KW system that tracks.  That's around 40 panels isn't it?  Can you get any photos?

Casey

I suppose, dozens of the buggers around here getting paid 80.2 cents per Kwh while hydro electric can generate at 5 cents but is spilling water past the turbines due to production surplus. Makes Ontario  power the most expensive in North America .
  I'll post a few images one of these days .

LowGear

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Re: Blasphemy..... Solar power.
« Reply #127 on: March 20, 2017, 04:46:48 PM »
Well if I were one of the buggers I'd call myself a very luck bugger.  They have a similar program here in Washington state, USA but it's coming to an end in 2020. 

Don't you worry big oil will raise her pretty head pretty soon.  Too bad they're sloshing water rather than reducing fossil fuel consumption.

I'm still hoping to see a 10 KW array that moves.

Casey
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Kubota BX 2230
Witte BD Generator
SunnyBoy 6000 + SolarWorld 245

buickanddeere

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Re: Blasphemy..... Solar power.
« Reply #128 on: March 21, 2017, 07:06:52 PM »
Burning natural gas for 17cents instead or using hydro electric for 5-6 cents

mike90045

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Re: Blasphemy..... Solar power.
« Reply #129 on: March 22, 2017, 11:15:45 AM »
Panel angle depends on your latitude, and you would normally optimize panel angle for the sun angle at your month with the greatest heating degree days.
Close counts.  If you are using polycarbonate glazing, you should also be trying to minimize stagnation time through the summer........

For my PV array, I set it for the optimum winter angle, to reduce the generator run time and enhance self-cleaning via rain, summer, worse angle, but much better weather and more hours to recharge the batteries.
 
For my rooftop water heater, I was stuck with the angle of the roof, good for summer, nearly useless in winter, it reflects instead of harvests.  But in winter the Masonry Heater has a hydronic coil and preheats my water in a 80 gal tank in a 2nd floor closet.

BruceM

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Re: Blasphemy..... Solar power.
« Reply #130 on: October 22, 2017, 04:00:38 AM »
I'll try and get some pictures of my tilt rack design for my neighbors soon, Glort.  Possibly tomorrow if my leg is better.

I'm in AZ so steel racks hold up just fine here.  We just bolt the angle iron frame directly to the PV panel aluminum channel. I laugh when I see the prices for store bought mounting racks and hardware. 

We are in a very remote, rural area so we are concerned about function, not appearance.  Your area is very different.  We have no "councils" meeting unless the natives are angry ;).   Seriously, the Apaches are to the south, Zuni to the East, Navajo to the north just past the Petrified Forest, Hopi NE.  My land has much worked stone from the Pueblo related people who lived here 1000 years ago and is covered by both marine fossils and softball to basketball sized volcanic rocks as well as some large petrified logs.



 

Samo

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Re: Blasphemy..... Solar power.
« Reply #131 on: October 22, 2017, 04:42:57 AM »
Nice laboratory Glort very smart use of waste reflected sun to help dry the clothes :D  I think the only thing you're missing is a treadmill generator for your Border-collie...  if it's anything like mine she'd power your whole suburb :D

Lister CS 12/2 & JKSON 10/1 Listeroid

BruceM

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Re: Blasphemy..... Solar power.
« Reply #132 on: October 22, 2017, 09:24:21 PM »
Here's my neighbor's racks; each as 3 panels (5 for 120V and one 12V which powers his engine room/120VDC power controller/wireless phone and internet.  They are partially cantilevered and one man can easily change the tilt supports, which are 3/4" EMT with smashed flat ends.   The uprights are 3"x3 x3/16 angle.  Each rack is 10 feet long. I split these to make them easier to tilt as the total length is 20 feet.  There is no visible movement or flexing with gusts of 100 MPH.  The panels go all the way to vertical and fully horizontal.  My neighbor and I both do just 2 tilts- one for the summer months and one for winter.  Our priority is for winter gain, we have excess power all other months.

On the next iteration we will go a bit over 16 foot in length for a single 5 PV panel rack with 3 vertical supports, probably 3" round pipe instead of angle depending on steel prices.  I will raise these vertical posts about 6 inches and put the pivot point just above the center of the panel.  The steel above the panel will continue to make it somewhat underbalanced.  We'd like it to be a one man job to tilt the single 5 panel rack. The seasonal angle support vertical posts will be only 12" above ground and perhaps 2x2x1/8 angle.

We need to keep the bottom edge of the panels about 1 foot above ground in winter mode due to snow. It is extremely rare that we would have that much standing snow in winter.

If you look at the commercial rack$, you will quickly see why it makes more sense to have your own custom racks welded up from a local steel source.









BruceM

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Re: Blasphemy..... Solar power.
« Reply #133 on: October 22, 2017, 09:43:47 PM »
Here's my original racks which are a two man job to tilt. When they were built 10 years ago my local steel supplier built them for $150 for steel and welding.  These are smaller 175 watt panels-  in larger panels it would take 3 men.  Thus the change to the split cantilevered design.

My next solar project will be to add an additional 1200-1500 watts of PV. This will provide additional power for my 120VDC inverter for well pumping and washing machine is a 5 panel rack with just 3 supports, and even better balanced.  The inverter will only be used on sunny days (plenty of those here in AZ), as we want to keep our bargain battery banks lightly discharged. The 10 - 110AH  Walmart Marine batteries cost about $1000 to replace, and are lasting  4.5 years. This is a minimalist 120VDC off grid system but it has served me and now my neighbor and our special disability needs very well.

 



BruceM

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Re: Blasphemy..... Solar power.
« Reply #134 on: October 23, 2017, 01:06:26 AM »
 I also was surprised at fairly good performance of PV on partly cloudy days.  So good, in fact that I abandoned my plans for a DIY windmill.  PV is easier and cheaper.

I have never seen tilting racks on a home's roof.  That certainly adds a serious new twist to the design.  I have 20 acres so ground racks seemed best to me.  I do have a single fixed 12v panel on each on my outbuildings...for those I only make steel brackets.  The largest is on my shop, and powers my one 110ah AGM BATTERY for solar hot water and house heating pumps.  It gets left in winter tilt all year.  That battery lasts more than 8 years. 

Your access to the big fork lift batteries for bargain prices makes them very appealing.  Tesla batteries are presently not competitive for stationary power by my calculations either, even with new wet lead-acid batteries.