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diy solar

diy solar

Complete Off-Grid House - 3000 sqft Ranch - Michigan

I think the near vertical angle on the solar panels will help to maximize your critical winter production.
In my area, I roughly use a 3X height of object for shadow length on the shortest day of the year so your calculations look OK to me.

I was just looking at this from another perspective. If I can adjust the tilt from 85deg more towards 0 (or in between) during the late spring / summer months, I have way less shadow.

Check it:

1000022219.jpg
 
If your sketch is to scale, the shadow from each row of panels is falling on next row at about 90 degrees.
If that would put a shadow on cells, it greatly affects production.

I have been thinking any shadow should only be allowed when sun is at 45 degree or shallower angle, because production drops off more rapidly beyond that.

Also, if some cells are under full shadow when others are under full sun, maximum current of panel flows through bypass diode around shaded cells.
Some manufacturers say "don't do that". The diodes can overheat and melt/crack the panel.
Bypass diodes only intended for when current is significantly lower.
 
I was just looking at this from another perspective. If I can adjust the tilt from 85deg more towards 0 (or in between) during the late spring / summer months, I have way less shadow.

Check it:

View attachment 288527
If you are designing for the worst month, December, then every other month should exceed your needs. I see no reason or benefit to try to improve production in the other months unless your consumption requires it.
 
If your sketch is to scale, the shadow from each row of panels is falling on next row at about 90 degrees.
If that would put a shadow on cells, it greatly affects production.

I have been thinking any shadow should only be allowed when sun is at 45 degree or shallower angle, because production drops off more rapidly beyond that.

Also, if some cells are under full shadow when others are under full sun, maximum current of panel flows through bypass diode around shaded cells.
Some manufacturers say "don't do that". The diodes can overheat and melt/crack the panel.
Bypass diodes only intended for when current is significantly lower.
Drawing is not necessarily to scale, but the shadows shouldn't be significant in the winter (< 15 feet per row) and in the summer will not be large either once I adjust the tilt more towards 0 degrees.
 
If you are designing for the worst month, December, then every other month should exceed your needs. I see no reason or benefit to try to improve production in the other months unless your consumption requires it.
Exactly. That's what I'm showing in my drawing
 
The big boy here uses 8" SCH 40 poles buried 9.5 feet in the ground with 40 plus inches of concrete around each pole. The cost per pole and concrete isn't cheap. I spent more than what I paid for the used mounts on the poles and concrete. The shadow is quite large in winter at 60°. Around winter solstice, trees to the west don't have any leaves but just the shadow from the branches is enough to kill production by over 50% by 3 PM, you can just barely see any of that shadow on the panels but it is there.

1743335636053.png

This one uses 6" SCH 80 poles and about 34" of concrete 7.5 feet deep. I paid $900 per pole during 2021 and concrete was around $1200. This array will produce all day year round as there is no shadows. I would have liked to install some panels behind it but the shadow in winter is long.

1743335792158.png


As the angle is increased, the amount of force placed upon the foundation and the pole base increases exponentially. The smaller array has around 72,000 lbs of force at the base of each pole in 105 mph winds at 60° tilt. The uplift is substantial in 60 mph winds, you need plenty of ballast underground with high tilt angles.
 
Drawing is not necessarily to scale, but the shadows shouldn't be significant in the winter (< 15 feet per row) and in the summer will not be large either once I adjust the tilt more towards 0 degrees.
While the shadow is short mid day, you will lose some production the rest of the day when the sun is lower in the sky and to the sides. Take the above post, each array is on each side of that shed and morning/afternoon cast a shadow on the shed wall above the overhead door opening. I plan on installing panels above the door openings but have to space in about 10 feet to help with that shading.

You will lose at least 25% of yield most likely due to this effect.
 
While the shadow is short mid day, you will lose some production the rest of the day when the sun is lower in the sky and to the sides. Take the above post, each array is on each side of that shed and morning/afternoon cast a shadow on the shed wall above the overhead door opening. I plan on installing panels above the door openings but have to space in about 10 feet to help with that shading.

You will lose at least 25% of yield most likely due to this effect.

I think I'll be okay with my design and separating the panels by ~10' in between rows. Just as a recap:
  • (132) Panels = (22) Panels x 2 (Double Stacked in Portrait Orientation) x 3 Rows
  • = 85.14 kW STC or 67.3 kW NMOT
Using PV Watts, I set the Loss Breakdown as follows:
  • Soiling = 2% (Default)
  • Shading = 3% (Default)
  • Snow = 3% (Especially at 85deg Tilt)
  • Mismatch = 2% (Default)
  • Wiring = 2% (Default)
  • Connections = 0.5% (Default)
  • Light-Induced Degradation = 1.5% (Default)
  • Nameplate Rating = 1.0% (Default)
  • Age = 15% (The worst case "Long Term Efficiency" panel I'm looking at is 85%)
  • Availability = 3% (Default)
With Tilt set to 85%, Azimuth at 180 degrees, Inverter Efficiency set to 90%, and Bifacial set to no, I get the results below, of which each month exceeds my requirement of 3714 kWh by a decent margin.

1743363147293.png

If I increased the shading to 10%, the worst-case number is 3711 (vs. my requirement of 3714).

Do we all concur that this setup should be okay?
 
I think I'll be okay with my design and separating the panels by ~10' in between rows. Just as a recap:
  • (132) Panels = (22) Panels x 2 (Double Stacked in Portrait Orientation) x 3 Rows
  • = 85.14 kW STC or 67.3 kW NMOT
Using PV Watts, I set the Loss Breakdown as follows:
  • Soiling = 2% (Default)
  • Shading = 3% (Default)
  • Snow = 3% (Especially at 85deg Tilt)
  • Mismatch = 2% (Default)
  • Wiring = 2% (Default)
  • Connections = 0.5% (Default)
  • Light-Induced Degradation = 1.5% (Default)
  • Nameplate Rating = 1.0% (Default)
  • Age = 15% (The worst case "Long Term Efficiency" panel I'm looking at is 85%)
  • Availability = 3% (Default)
With Tilt set to 85%, Azimuth at 180 degrees, Inverter Efficiency set to 90%, and Bifacial set to no, I get the results below, of which each month exceeds my requirement of 3714 kWh by a decent margin.

View attachment 288785

If I increased the shading to 10%, the worst-case number is 3711 (vs. my requirement of 3714).

Do we all concur that this setup should be okay?
You have backup generator? Or some other way to heat house without electricity? I mean those calculations are only averages and at least here up north fluctuate a lot monthly while yearly production is much more accurate.

"Bifacial set to no", but still going to use bifacials I hope? They work quite nicely with high tilt angles and like white surroundings, especially snow. They are heavier though and can be more expensive but also less expensive like in my case.
 
You have backup generator? Or some other way to heat house without electricity? I mean those calculations are only averages and at least here up north fluctuate a lot monthly while yearly production is much more accurate.

"Bifacial set to no", but still going to use bifacials I hope? They work quite nicely with high tilt angles and like white surroundings, especially snow. They are heavier though and can be more expensive but also less expensive like in my case.

I will have a diesel generator which will provide electricity for running the geothermal field.

I will be running bifacial panels for sure, I just wanted to be turbo conservative.

I think the calculations are good though and now I need to figure out the mounting racks, batteries, exact panels, inverters, and other equipment.
 
I will have a diesel generator which will provide electricity for running the geothermal field.

I will be running bifacial panels for sure, I just wanted to be turbo conservative.

I think the calculations are good though and now I need to figure out the mounting racks, batteries, exact panels, inverters, and other equipment.
With backup generator I think you be just fine. My predicted (PVWatts) estimate were 42MWh for my 44,1kWp vertical array and it actually did 44,6MWh first year. Your calculation parameters are much more conservative so I bet it'll work nicely.
 
Anyone have any thoughts regarding racks? I'm going to need (3) rows that are 100' long and can hold double stacked panels in portrait orientation.
 
Anyone have any thoughts regarding racks? I'm going to need (3) rows that are 100' long and can hold double stacked panels in portrait orientation.
The usual suspects would be mt solar on pole mounts (big bucks) or something like these Sinclairs (not recommending shop just a link that came up). There's also Tamarack and Integra amongst others.

 
The usual suspects would be mt solar on pole mounts (big bucks) or something like these Sinclairs (not recommending shop just a link that came up). There's also Tamarack and Integra amongst others.


Sounds good! What about panels? I listed several in my post above and could use some input on if one of those is a better fit than the others, or if there are other ones I should consider.
 
Sounds good! What about panels? I listed several in my post above and could use some input on if one of those is a better fit than the others, or if there are other ones I should consider.
I've just gone with whatevers cheapest cost per Watt at the time. First ten was Hyundai 300W, then 370W Aptos and 375W Vikram bifacials. Main goal for me is trying to have Voc around 37V if possible allows me to have more on a string. Thr Hyundai have that but the others are closer to 41V.
 
Anyone have any thoughts regarding racks? I'm going to need (3) rows that are 100' long and can hold double stacked panels in portrait orientation.
85° adjustable tilt would have to be custom made, if you can find someone will to do it. Sinclair only goes 55° max and they will limit pole height after it is run thru engineering. They do portrait but don't offer what you want. MT Solar is landscape only.

What are you considering for an adjuster? At 100 feet long, you will have to have a helper for adjustment or spend time walking from one end to the other, adjusting each adjuster slightly. I can turn about 3 turns before I have to go to the other adjuster, then turn that one the 3 plus another 3 and keep working back and forth. The cornish rocker does not have this aspect but it is about 60° tilt max and landscape pattern. It would take some engineering to get rows farther back at a higher elevation plus access for the tilt.

 
85° adjustable tilt would have to be custom made, if you can find someone will to do it. Sinclair only goes 55° max and they will limit pole height after it is run thru engineering. They do portrait but don't offer what you want. MT Solar is landscape only.

What are you considering for an adjuster? At 100 feet long, you will have to have a helper for adjustment or spend time walking from one end to the other, adjusting each adjuster slightly. I can turn about 3 turns before I have to go to the other adjuster, then turn that one the 3 plus another 3 and keep working back and forth. The cornish rocker does not have this aspect but it is about 60° tilt max and landscape pattern. It would take some engineering to get rows farther back at a higher elevation plus access for the tilt.


The beauty of the design is that I shouldn't ever have to adjust it - ever - because even with extreme shadows (25%) in the summer, I still would produce a crapton of energy. See below @ 25% shading (which shouldn't happen based on the height staggering of my design). Even IF they had this shading, the lowest amount in the summer months is 3293 vs. 3714 of my requirement, but I won't be using my electric heating like I will in the winter.

1743435645978.png
 
Since they are probably not that far away from you, you could save ~$2,500 in shipping with Sinclair if you can pickup yourself.

Sinclair Designs & Engineering
1104 Industrial Blvd
Albion, MI 49224
 
I'm good with that! I just need 100' worth of panels.
Decide what AIOs or charge controllers you're going with, determine the best VOC needed to get series string with high VOC, but low enough for cold weather increases, shop for panels in that VOC range and width you need to fill 100' span. I'm guessing you'll fit max of 27 panels in a row, 9S strings would work nice if that's the case.
 
Decide what AIOs or charge controllers you're going with, determine the best VOC needed to get series string with high VOC, but low enough for cold weather increases, shop for panels in that VOC range and width you need to fill 100' span. I'm guessing you'll fit max of 27 panels in a row, 9S strings would work nice if that's the case.

I'm open to all recommendations for equipment! I listed several brands a few posts ago (regarding panels) and I'd love to get people's thoughts.

By the way, Sinclair told me that 85deg won't happen unless I DIY, so I need to design for 60 degrees and not go vertically staggered.
 
I'm open to all recommendations for equipment! I listed several brands a few posts ago (regarding panels) and I'd love to get people's thoughts.

By the way, Sinclair told me that 85deg won't happen unless I DIY, so I need to design for 60 degrees and not go vertically staggered.
I've given my advice on what equipment has been working for me many times. It's all I have experience with so I can't really comment on anything else.

I think others mentioned 85 degrees would be to steep for those mounts.
I can't help you there. I built my mounts using inspiration from this thread.
 
Which panels should I really be considering? The best ones I found are:
  • Risen / Mono / RSM132-8-720-740BHDG
  • Hanerson / Bifacial / HN21H-66HT 730W
  • Seraphim / Mono / SRP-720-BHC-BG
  • Trina Solar / Bifacial / TSM-NEG21C.20 720W
  • Thornova / Bifacial / TS-BGT66-G12 720W (or BW-series)
  • Canadian Solar / Bifacial / CS7N-720TB-AG
From those choices I'd go with Hanerson (never heard before) because of it's specs. It has annual power decline of 0,3% (exellent), 23,5% efficiency (excellent), 90%+-5% bifaciality (excellent) and -0,24%/C Tc Pmax which is better than excellent. I mean I haven't seen Tc that low.

Of course it depends $/W too.
 
I'm open to all recommendations for equipment! I listed several brands a few posts ago (regarding panels) and I'd love to get people's thoughts.

By the way, Sinclair told me that 85deg won't happen unless I DIY, so I need to design for 60 degrees and not go vertically staggered.
 

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