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Does Solar Panel Placement Really Matter?

 
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We all know solar panels harness the sun's energy, but have you ever stopped to think about whether WHERE they're placed truly impacts their efficiency?

I recently came across some information suggesting that the angle and direction of solar panels might not be as crucial as we've been led to believe. This challenges the common notion that rooftop installations are inherently less efficient than ground-mounted systems due to limitations in positioning.

And the reason why I am interested in this is soon I will move to another city and I want to purchase some solar panels for my house, but I just do not know where to start.

So, I am now wondering:

Is the obsession with optimal solar panel placement overblown?
Do advancements in solar technology minimize the impact of placement?
Are we overlooking the potential of rooftop solar in favor of ground-mounted systems?

Do any of you guys could help me out with that, thanks in advance?
 
rocket scientist
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Hi Leo;
High voltage panels and MPPT controllers allow you to create maximum power in less-than-ideal conditions.
Low voltage panels rely on optimum position to gather as much energy as they can.
 
pollinator
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The money it cost to installing a ground based solar tracking system that moves on 2 axixes could install "2x" the amount of solar panels on a less than ideal roof.
So the question now becomes is the tracking system 200% as productive the answer is usually no, instead it might be 19% more productive.  

There is also the fact that solar panels last 25years but a tracking system propably doesn't. It has moving parts and isn't as hands-off and needs maintainace.

While it is awesome to produce an extra 10KWH/day, it's even better to use less KWH/day.  So think of some way on how to do that, usually it doesn't just help your energy/C02 footprint, it probably helps your mental health and physical health.

I am also a fan of installing an extra solar panel covered carport/garage/makerspace structure. I would be getting double the usuage for almost the same money.

 
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As someone who has been actively living with solar power for 15+ years I think I can contribute a little here. For myself I like having panels arranged in a pattern starting out here in Virginia at facing about 160 on the compass with one bank of panels. Then another at say 180 another at 200 and another at 220 and finally the last set at 240. These are rough numbers not exact. But here where I live we often have cloudy mornings and sunny afternoons. But the real reason for my crazy scheme is because WE and most people use more power in the afternoons and evenings than in the mornings. The more of the power you can use as it's made versus storing it gets you a better return on your investment because less power is lost in all the charging and discharging. Every single time power changes form, voltage, amperage etc. a little power is lost in the process.  

Also panels run hotter when the sun is directly on them and while I have NO ACTUAL PROOF it seems to me that the angle being less than optimal for power production is also less hot. Panels lose a LOT of ability to make power as they heat up.  So again without any proof it seems to me the less hot panels often make more power with less direct face on sun than much hotter panels in direct face on sun.  

Sadly most of my system is NOT setup this way as it was already done by the time I figured this out. BUT I have been slowly making changes in this direction and they appear to be paying off.

NOTE When I say a set or bank of panels what I referring to is a string wired in series to the limit or up near / kinda close to the limit of your equipment. I never like pushing electronics to the limit! These strings are then wired in parallel to the charge controller.
 
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Absolutely.  I built my solar arrays on rotating ground mounts, adjustable for both azimuth and declination, and I can change to positioning of the panels in real-time and measure the differences.  I can basically double my total solar output throughout the day by rotating my panels East to West.

A tracking array does NOT have to have a complicated motorized mechanism.  I simply walk out and rotate my arrays by hand to face East in the morning, South around noon, and Westward in the afternoon.  I make three adjustments per day to get these benefits.

I have to say it is almost endlessly entertaining to fiddle with my array angles to squeeze out those extra 100W.  I'm outside in the utility room monitoring the system output with my morning coffee to watch the watts raise as the sun comes up.  I call it "watching the solar channel".

If I was not on the land each day, but rather at a day job in town, then this manual system would not work as well.  But, for an on-site homesteader, it's perfect.  It starts with a 10' long piece of 3.5" schedule 40 pipe that I sink 3' in concrete.  I slip a 4' long piece of 4.0" schedule 40 pipe on top of that with a flat cap welded on the top.  A double unistrut beam with truss supports then gets welded onto that cap.  I call the whole assembly the "T-post".

I then bolt the solar array frame onto the T-post via heavy duty steel door hinges.  The azimuth is controlled by rotating the array to a certain position, and then tightening down locking bolts to keep it in place.  I rock the frame to the correct angle to the sun and hold it in place by 3/4" steel struts.  The whole thing, that can hold as many as six 250W residential panels, cost about 400$ in terms of steel and concrete mix.  I rented a two-man auger to drill the 18" holes 36" deep in the ground.

My system is primarily designed around supplying power to my 240VAC well-pump, which needs ~2100W to run.  By rotating my panels East to West, I can pump water continously from 8am till 4pm.
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I think it’s called the “cosine effect”.  Basically there’s not much power loss if there’s only a small angle between the panel’s orientation and the sun.  A large misalignment will have a more significant loss.

To see this, image search “cosine wave”, or take a calculator, set it to degrees, type in the offset angle, press “cos”, and this will be a number between 0 and 1 representing the fraction of peak power you’re getting.
 
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I don't have solar, but I have installed it on a commercial and industrial level.
Those systems were on flat ground or flat roofs, with static racks.
When considering solar for my own home, I quickly realized that a two story pitched roof with north/south facing gable ends would make  professional instalation expensive and diy instalation difficult and terrifying.

I have instead built a "deck" with a south facing pitched roof.
For now,  it just offers shade and a place for the chicken coop, but it's situated with solar panels in mind.


 
pollinator
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Leo Breydon wrote:We all know solar panels harness the sun's energy, but have you ever stopped to think about whether WHERE they're placed truly impacts their efficiency?

I recently came across some information suggesting that the angle and direction of solar panels might not be as crucial as we've been led to believe. This challenges the common notion that rooftop installations are inherently less efficient than ground-mounted systems due to limitations in positioning.

And the reason why I am interested in this is soon I will move to another city and I want to purchase some solar panels for my house, but I just do not know where to start.

So, I am now wondering:

Is the obsession with optimal solar panel placement overblown?
Do advancements in solar technology minimize the impact of placement?
Are we overlooking the potential of rooftop solar in favor of ground-mounted systems?

Do any of you guys could help me out with that, thanks in advance?


Well it depends on how important that power is to you and how much array you have. I am attaching a small theoretical array I put together with my software in my location is shows an array at 270 degrees, 225 degrees and 180 degrees. I have found with an Mppt charge controller within 15 degrees of true south the difference is insignificant. the same applies to within 15 degrees of ideal angle. the bellow charts assume a 1kW solar array for easy calculation. As I would assume it affects you far more in the winter when the sun is lower then the summer.  Hope this helps visualize things. The bar graph is daily production the chart is monthly.
Cheers,  David Baillie
daily-production.jpg
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monthly-production.jpg
[Thumbnail for monthly-production.jpg]
 
pollinator
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One thing to keep in mind is snow covering the panels.

My panels are nearly vertical.  Snow and ice rarely stick to them and when it does it has fallen off by the afternoon of the first sunny day after the ice storm.  I see lots of roof top systems that are a at a low angle and they have snow covered panels most of the winter.

My panels may get less power than they should because of the wrong angle but they are still making power quickly after a snow fall because they don't get covered in snow.

The self shedding of snow is important because I plow snow for a living.  So I usually leave the house in the dark while it is still snowing and get home in the dark.  If my panels were covered in snow all day I would be coming home to dead batteries.  But by shedding snow the panels usually make at least some power even when it is cloudy.

I think a better option is a ground mount where the angle can be adjusted easily by hand.  That way when the weather is good the panels can be adjusted monthly for best production, but when there is a chance of snow they can be set vertical.
 
J Hillman
pollinator
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Another important thing to consider is WHEN do you want the power.  If  there is a certain time of year or day where your power needs are higher it may be best to point your panels for best power a that time and accept less power the rest of the time.

Our autumns tend to be over cast and we still want to run a fridge and loads for preserving the harvest.  The panels production can easily fall short or our needs at that time so it may be helpful to angle our array so that is the time the panels are most efficiently harvesting sunlight.

If you are in an area known for its cloudy mornings and sunny afternoons you should point your slightly west.  Or if you have sunny mornings but shaded in the afternoon you should point your panels more east.
 
pollinator
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To add on to what has already been said, there are now not only much cheaper solar panels, but you can find bifacial solar panels for not much more money. These panels are designed to produce some amount of energy from light hitting the back side of the panel. This makes them useful for projects where they aren't flat close to a surface like a roof. It's particularly beneficial for any situation where you have a few feet or more behind the panels. It also can make more power for installations facing more towards the east or west.

While my current PV solar plans can't make good use of the bifacial panels, I can certainly see one good use in my situation. Here it is incredibly hot, and very humid largely due to the extreme amount of evaporation that occurs. I've noticed a large difference in vegetation when it has a good amount of shade through part of the day. You can often find a lot more growth along walls and fences than out in the open with no shade. Planting my sweet potato plants so the root zone stays in the shade as the sun gets higher in the sky and letting the roots grow out to the sunny areas seems to keep them very happy.

I could potentially do some sort of agrivoltaic system with either panels facing east and/or west and providing a bit of shade to the ground while making power, or put them higher up off the ground to cast a shadow behind them and plant vine plants like watermelon or sweet potato so the root zone is shaded during the worst part of the day, all while making more power than I would with standard panels. This is particular to my area, but any situation that has you using panels with space behind them to capture either direct or reflected light can increase the total power output using bifacial panels.
 
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