Why are all the panels facing east or west

MarkSolar

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Drove home from a vacation yesterday, passed a large solar farm probably 5-10 acres. All the panels were facing either east or west, none facing south although the terrain was pretty flat so they could have faced the panels any direction without a change in mounting cost. So why would they mount them east and west? Is it possible the utility has so many homeowners with south facing panels that they get more economic advantage by harvesting more power in the mornings and evening?
 

newbostonconst

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They need power in the morning and afternoon more then during the day. There might already be a lot of south facing solar in the area.
 

sunshine

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Drove home from a vacation yesterday, passed a large solar farm probably 5-10 acres. All the panels were facing either east or west, none facing south
Possibly a similar amount of power produced throughout the day.
The midday sun striking both east and west sides and at a higher angle to compensate for no southern aspect.
 

740GLE

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Morning peak and after noon peak have higher prices $/kwhr. With all solar facing south system load mid day is actually becoming lowest part of the day and negative kWhr prices hurt the bottom line for non dispatchable power.

Look up “duck curve”.
 

FilterGuy

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Drove home from a vacation yesterday, passed a large solar farm probably 5-10 acres. All the panels were facing either east or west, none facing south although the terrain was pretty flat so they could have faced the panels any direction without a change in mounting cost. So why would they mount them east and west? Is it possible the utility has so many homeowners with south facing panels that they get more economic advantage by harvesting more power in the mornings and evening?
That does seem odd, but as others have noted it may be an attempt to add 'morning' solar to balance out an over-abundance of afternoon solar.

Intermittent renewable power is turning into a real problem for utility companies. In the past the variance between peak and off-peak demand was lower, much more predictable and changed at a slower rate. This meant that they could use their base-load generators to manage the load. Now with solar and wind so prevalent, some areas have the swings from negative demand to very high demand that happen in a relative short period of time. It is very hard (or impossible) to adjust their base load generators quickly enough to manage it.

In some states like CA and TX, More renewable will create more and more problems till they figure out how to have more storage to manage the intermittent nature of renewable power. Sadly the polititions don't seem to understand or care so they are pushing more renewable power before they have these problems sorted out.

BTW: where do you live?
 

MarkSolar

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BTW: where do you live?
Far west fringes of Chicago metro, but the array I saw was north of Rice Lake, Wisconsin on my way home. I found this info about the array, it was just built last year. It does belong to the utility company, and it's 3.75MW
 
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FilterGuy

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Far west fringes of Chicago metro, but the array I saw was north of Rice Lake, Wisconsin on my way home.
Interesting, I would not have guessed that. I did not think Wisconsin had enough renewables for it to be a problem yet so I would think they would have optimized for maximum power, not for balanced power. However, to be honest, I have no idea what the power mix in Wisconsin is like.

Also, that far north it becomes more important to have a more southerly angle to the panels.... I would have thought facing them SE and SW would have maximized the power *and* ballanced the morning/afternoon production.

It would be fun to talk to the operator of the solar farm to get an explanation of what they are doing.
 

100 Proof

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What time of day was it? Most utility scale projects where I live have singe axis trackers that will reset from west to east at the end/beginning of the daily cycle. Could you have caught them in the midst of a daily tracking reset?
 

FilterGuy

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What time of day was it? Most utility scale projects where I live have singe axis trackers that will reset from west to east at the end/beginning of the daily cycle. Could you have caught them in the midst of a daily tracking reset?
I thought of that too.... but tracking systems have become less common as the panel prices have dropped. (It is cheaper to add panels than it is to add trackers)

As I think about it now, it could be that there is a mix of older panels that have trackers that have reset to face east and newer panels that don't have trackers and are 'fixed' facing west. (Now I am getting into pure speculation based on very little information... 🙂 )
 

FilterGuy

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I found this info about the array, it was just built last year. It does belong to the utility company, and it's 3.75MW
I just noticed the link. The tiny picture seems to show the mounts without the panels..... but I can't tell if they are tracking mounts. Also, it sounds like an all-new install so that puts a lie to my old/new speculation.
 

MarkSolar

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If they're tracking mounts it seems to make even less sense. I went through there about 1pm and they were all pointed east or west, none pointed south.
 

740GLE

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Maybe they are still commissioning the facility or ran into supply issue with long lead time parts.
 

FilterGuy

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If they're tracking mounts it seems to make even less sense. I went through there about 1pm and they were all pointed east or west, none pointed south.
The tracking may swing them from east to west only.

The article about them is dated May 11, 2021 (Updated Aug 17, 2021) and talks about the solar farm being under construction. It says it will be operational in July. However there is a fundamental law of nature the requires construction projects to run late :) . My *guess* is the farm is not operational and the panels are not yet tracking. They are just sitting at whatever location they were after the install. They may not even have their final angle on the mount. I am guessing that once complete and operational, they will have a southerly tilt and track east to west.....but that is just a guess.
 

MarkSolar

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My *guess* is the farm is not operational and the panels are not yet tracking. They are just sitting at whatever location they were after the install. They may not even have their final angle on the mount. I am guessing that once complete and operational, they will have a southerly tilt and track east to west.....but that is just a guess.
That makes sense, I wasn't paying attention to the dates.
 
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