Panel tilt

pda1

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I'm trying to figure out optimal fixed panel tilt for my latitude and need some help.

I'm at North 40° West 75° (about)

The panels will be in a fixed position facing True South.

What angle would you suggest?

Thanks,

Peter
 

LB3

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About 40 degrees would be ideal year round, but usually you would lean towards better production in the summer when there is more daylight hours, so something around 30 degrees?

Consider this:
That’s only true for grid tied installations when optimizing for maximum annual power production. If this is an off grid application, it should be optimized for the worst stretch of cloudy winter days.
 

pda1

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About 40 degrees would be ideal year round, but usually you would lean towards better production in the summer when there is more daylight hours, so something around 30 degrees?

Consider this:
So if I'm at North 40° then I should tilt my panels to 40° up from the horizontal?
 

chrisski

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Look at the calculator in my signature block and play with some numbers And see what the best tilt is.

Not counting AC, my power production is by far the most on winter nights because of the propane heater blowing and the electric it uses. So, I may tilt higher for that December shortest day of the year. If I do get my AC working on solar, panels will be flatter because I use the AC in the summer months. AC takes so much more than everything else, I would not worry about winter production because there’s be so many panels that in the reduced need in the winter months, any angle would work.

Kind of comes down to an energy audit based off low production verse high production to include at different times of year.
 

pda1

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Look at the calculator in my signature block and play with some numbers And see what the best tilt is.

Not counting AC, my power production is by far the most on winter nights because of the propane heater blowing and the electric it uses. So, I may tilt higher for that December shortest day of the year. If I do get my AC working on solar, panels will be flatter because I use the AC in the summer months. AC takes so much more than everything else, I would not worry about winter production because there’s be so many panels that in the reduced need in the winter months, any angle would work.

Kind of comes down to an energy audit based off low production verse high production to include at different times of year.
Great calculator but I'm confused about the Installed peak PV power [Wp] *

I read the explanation but it's beyond me...
 

sunshine

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Tilt for winter.
Better for the snow probably? We don't get that cold but the greater winter tilt in summer should keep the panels cooler and cleaner!
 

RV10flyer

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At 38 deg north latitude, I use more kWh in the winter with my heat pump systems, so I’m going with somewhere between my “Optimal year around” angle of 38 deg to 53 deg “Best Winter Performance” angle. Measured from horizontal.
 

Horsefly

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Here's a site that has been around for quite a while. I think it is a little to nerdy, and probably overkill for trying to figure out the tilt, but it is hard to argue with the logic: https://www.solarpaneltilt.com/

My place is at about 38°N latitude, and we pretty much only use it in the Summer. We went for about a 40° angle, and it has been fine.
 

pda1

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Now I'm progressively getting confused.

Tried some android apps which were just nag-advertisement types. They do give you an angle but there's a discrepancy in results between what fixed angle is best in Northern latitudes.

So....I still have no solid answer.

At North 40° at the Summer solstice the Sun's declination at LAN (Local Apprent Noon) is North 23° 26.2' and the corresponding angle of the Sun above the horizon is 73°. So, simply, the panels should be tilted to 73°. This would only be true for the Summer Solstice. At the Winter Solstice the Sun's angle would be 27°.
 

pda1

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Here's a site that has been around for quite a while. I think it is a little to nerdy, and probably overkill for trying to figure out the tilt, but it is hard to argue with the logic: https://www.solarpaneltilt.com/

My place is at about 38°N latitude, and we pretty much only use it in the Summer. We went for about a 40° angle, and it has been fine.
Well, according that guy it's something like 38° x .76 + 3.1° = 32°

This is probably being "over-thought" by me.
 

Hedges

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That’s only true for grid tied installations when optimizing for maximum annual power production. If this is an off grid application, it should be optimized for the worst stretch of cloudy winter days.

That would be straight up.
Light comes from the glowing clouds.
(Or so I hear, I'm not the horse's mouth.)
 

wattmatters

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I'm trying to figure out optimal fixed panel tilt
What angle would you suggest?
It depends on what you are trying to achieve and the sort of system you have.

Optimal for what exactly?

There is a panel orientation which, provided there is no barrier to loads, will provide the highest annual output. That fine for grid tied sets ups with good feed in tariffs. But off-grid it may well be sub-optimal as it's more important to have power when you need it.

Without knowing what your needs are and the sort of system you have or propose then the answer is "it depends".

It may be more important to sacrifice overall production total to have better output in the Winter. Or to have a more even spread of production across the day. Or be able to recharge batteries earlier in the day, or cover aircon use in the late afternoon. Perhaps your location experiences morning fogs a lot at times of year you really need to extract the most, and it's better to face panels a bit more West rather than waste the end of the day with clear sky. etc etc
 

pda1

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It depends on what you are trying to achieve and the sort of system you have.

Optimal for what exactly?

There is a panel orientation which, provided there is no barrier to loads, will provide the highest annual output. That fine for grid tied sets ups with good feed in tariffs. But off-grid it may well be sub-optimal as it's more important to have power when you need it.

Without knowing what your needs are and the sort of system you have or propose then the answer is "it depends".

It may be more important to sacrifice overall production total to have better output in the Winter. Or to have a more even spread of production across the day. Or be able to recharge batteries earlier in the day, or cover aircon use in the late afternoon. Perhaps your location experiences morning fogs a lot at times of year you really need to extract the most, and it's better to face panels a bit more West rather than waste the end of the day with clear sky. etc etc
A very good point concerning the usual better part of the day for weather- more westerly orientation.
 

pda1

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Edited- I'm thinking making a ground mounted tilting array- not a pole mounted system.

Here's the simplest site so far- Solar Panel Tilt
 
Last edited:

svetz

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It really depends.

For example, I live in Florida and use almost no power in winter and a ton of power in summer. So, set the tilt for summer right?
Nope. Summer is also when we get a lot of rain.

But I live in Florida which has a great net-metering agreement. So, I should optimize for year round, right?

Well no, turns out what was most important to me was wind pressure on the roof (hurricanes <sigh>). So, I minimized those forces by having them flat on the roof.

But, I'd recommend SAM. It'll take into account where you live, your typical weather patterns, you can input your power consumption my month, add in any shade trees, and then you can play with the tilt to see what gives you the best for you. It's a beast, so watch the video tutorials if you go that way.
 

Hedges

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It depends on what you are trying to achieve and the sort of system you have.

... Or to have a more even spread of production across the day.

For that, multiple orientations.

A single orientation will have a curve of production that falls off when sun is at an angle.
Two PV arrays oriented at 10:00 AM and 4:00 PM will present 0.7x as much area toward the sun but have a more broad curve, flatter on top. It can deliver 1.4x as many kWh/day for a given peak power. These arrays could have separate SCC (or MPPT input), but can be paralleled into a single one for better utilization of the electronics.

Delivering more power early and late in the day means battery kept fully charged longer, starts recharging sooner. Smaller battery is sufficient to get through the night.

PV panels are cheaper than batteries, so good to over-panel and buy less battery. But limit max charge current to what battery can handle.
 

Wellbuilt

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It dosent really matter to much , today at 900am I’m getting 2800 watts my full power noon is 3700watts
at 10am I was getting 3200watts and absorb is lowering the charge rate ?
I’m at 42o at this time of year the panel are lined up 👍
in the winter I get about 2200watts on a good day at noon so about half .
Mid Summer time I get lots of power .
Things start dropping off now .
 
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