Installing a ground mounted array behind an existing array

Sterling9250 · Apr 22, 2024

I have an existing ground mounted, south facing solar array designed for four panels (I used a flat roof mount because it was easier and cheaper, bolted to concrete). I want to make another array and put it directly behind it. Is there a general rule of thumb like how far away it should be behind an existing array? Also is there a general rule of thumb how high it should be if it’s sitting behind an existing array? I could add some height to it quite easily if I wanted to.

I have 2 of the 4 mounted so far (waiting for another inverter to handle the more power).

wpns · Apr 22, 2024

Not sure what you have or what you want to do, maybe post some pictures? Go out in the daytime and see where the shadows are from the original array?

MichaelK · Apr 22, 2024

Yes, please post pics. A mount holding only four panels is not very big, so it might be worthwhile to simply remove it.

How high off the ground is the top edge of the panels? A higher mount in the back would need to clear the sun in December when the sun is at it's lowest angle.

Might be worthwhile to go out in the evening with a flashlight, and shine it at approximately the angle you think the sun will be at in December.

Here is pic of a ground-mount I myself made that holds up to 6 large residential panels, 1500W total. Remove the existing ground mount and install one or two of these. 3000W of solar might be all you need to live a very comfortable lifestyle.

Supervstech · Apr 22, 2024

Rule of thum is keep the new array out of the existing array's shadow.

Ampster · Apr 22, 2024

Supervstech said:
Rule of thum is keep the new array out of the existing array's shadow.

And to add to that, the shadow will be longer, the further North you are. Here is an online calculator:

Online calculator: Shadow length

Gives a vertical object shadow length for given coordinates and time. Also calculates shadow growth during whole day.

planetcalc.com

ricardocello · Apr 22, 2024

Supervstech said:
keep the new array out of the existing array's shadow.

Which can be really challenging at high latitudes in the winter (northern hemisphere).
More moderate latitudes are easier. I ended up with about 24 feet between arrays (but I have the room).

Sterling9250 · Apr 22, 2024

MichaelK said:
Yes, please post pics. A mount holding only four panels is not very big, so it might be worthwhile to simply remove it.

How high off the ground is the top edge of the panels? A higher mount in the back would need to clear the sun in December when the sun is at it's lowest angle.

Might be worthwhile to go out in the evening with a flashlight, and shine it at approximately the angle you think the sun will be at in December.

Here is pic of a ground-mount I myself made that holds up to 6 large residential panels, 1500W total. Remove the existing ground mount and install one or two of these. 3000W of solar might be all you need to live a very comfortable lifestyle.

Sterling9250 · Apr 22, 2024

MichaelK said:
Yes, please post pics. A mount holding only four panels is not very big, so it might be worthwhile to simply remove it.

How high off the ground is the top edge of the panels? A higher mount in the back would need to clear the sun in December when the sun is at it's lowest angle.

Might be worthwhile to go out in the evening with a flashlight, and shine it at approximately the angle you think the sun will be at in December.

Here is pic of a ground-mount I myself made that holds up to 6 large residential panels, 1500W total. Remove the existing ground mount and install one or two of these. 3000W of solar might be all you need to live a very comfortable lifestyle.

skyking1 · Apr 22, 2024

While the ideal condition is no shadow ever, if you are net metering those deep winter days have little relative value.

Sterling9250 · Apr 22, 2024

wpns said:
Not sure what you have or what you want to do, maybe post some pictures? Go out in the daytime and see where the shadows are from the original array?

Sterling9250 · Apr 22, 2024

wpns said:
Not sure what you have or what you want to do, maybe post some pictures? Go out in the daytime and see where the shadows are from the original array?

hwy17 · Apr 22, 2024

The shadows will be longer in winter too.

wpns · Apr 22, 2024

Can you just make that array wider?

Sterling9250 · Apr 23, 2024

wpns said:
Can you just make that array wider?

Considering it

MichaelK · Apr 23, 2024

Couple of options. Looking at the shadows from your loquat at 11:43am, it appears that you have your array facing East, is that correct? Take out the first array, and put in two of mine, that would hold 3000W. I think I could squeeze two in the space you have shown? What is that big bush in the far-right of the pic? Is that another food plant, or just a bush? It appears you have quite a bit of expansion space if you are willing to devote most of it to solar?

With the shade the arrays will provide, you might have a great spot to plant heat-sensitive herbs, rather than other garden plants.

Another option would be to turn your panels in the landscape orientation, with a higher array in back of it.

Installing a ground mounted array behind an existing array

Sterling9250

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wpns

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Ampster

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ricardocello

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