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Post Your Tesla Solar Layout

pdx_m3s

Active Member
May 18, 2019
1,563
1,411
Portland, OR
This is my proposed plan from tesla. All south facing roofs are shaded. Main house panels are on the 2nd story with zero shade. Does anyone know how many panels tesla will be able to add to this design using only the surfaces currently utilized? I count maybe 6? Two on main house four on garage?

You'll have to get up there and take a measurement to see if a third row will fit. It will be very tight, and there are usually array-to-ridge and array-to-gutter clearance/set-back requirements. Tesla isn't going to change the layout unless they know for certain if it can be done.

It looks like another row of panels (westward) on the west-facing plane will fit.
 
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h2ofun

Active Member
Aug 11, 2020
3,864
947
auburn, ca
You'll have to get up there and take a measurement to see if a third row will fit. It will be very tight, and there are usually array-to-ridge and array-to-gutter clearance/set-back requirements. Tesla isn't going to change the layout unless they know for certain if it can be done.

It looks like another row of panels (westward) on the west-facing plane will fit.
I have been told array to ridge can go to the top as long as there is 6 feet on the other side of the ridge. That is what I have now
 
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Hi everyone. I have learned so much from this forum. It really is a fantastic resource!

Until recently I didn’t seriously consider solar as an option because we suffer from the triple whammy of being in MA, no south-facing roof, and large maple trees along our southern property line that shade most of the afternoon sun. On the bright side (pun intended), MA has decent incentives, full net metering, and high electricity costs that help justify solar.

So, long story short, here is our 8.16kW 24 panel layout, which Tesla predicts will generate ~6.9kWhr/yr. (I am SO jealous of folks living in AZ & SoCal… :)

1619409988333.png


Tesla could only fit 20 panels on our east-facing roof, with the remaining 4 going on the west-facing roof. But from what I’ve read in this forum, Tesla is no longer offering SolarEdge inverters & optimizers, preferring instead to use their own string inverter. If I understand how MPPTs work, shaded panels on a string get 'deleted' electrically via bypass diodes in the panels, just so long as the string has sufficient voltage from the remaining unshaded panels to reach the minimum voltage of the inverter.

My concern with this layout is that the 4 west-facing panels would need to be on their own string given the different orientation from the 20 east-facing panels. But I've read that there is a minimum of five panels on a string. So, it would seem that the layout proposed by Tesla wouldn’t really work; the 4 west-facing panels would essentially be off almost all the time.

As I see it, I have two options. Either I press Tesla to remove the 4 west-facing panels and go with a 20 panel system, or I add more panels to the west-facing array so there is a better chance of reaching the minimum inverter voltage more often. I’d be OK adding another couple of panels, assuming I’d be adding some amount of power generation, especially in the winter months when the leaves are off the trees. But I wonder if I would just be throwing good money after bad…
 
Here's my layout that I hope to get installed this Summer. I actually did this layout myself after a few Tesla layouts. This allows them to use two or three strings, and places most of the panels on the West face and still pulls solar from the East. One Tesla layout placed all the panels on the West face, which I quickly rejected.

Panel Layout 2.jpg
 
Here's ours. It's not ideal, since there are panels facing all directions, and the twelve panels facing east-ish at the front of the house are pretty heavily shaded by trees for most of the day. But Tesla was conservative in estimating how much it would produce (just over 17 MWh annually from a 16.32kW system), and if it produces that much we'll be happy.

Screen Shot 2021-04-26 at 11.41.07 AM.png
 

pdx_m3s

Active Member
May 18, 2019
1,563
1,411
Portland, OR
12.24kW with and estimated annual production of 16,545. I had asked about shifting more panels to the back of the house, but they forgot to change the design. It's probably for the best bc there is 0 shading on the front. View attachment 658135

I would shift 2 of the west-facing panels to the front of the house and drop the third, or shift all 3 to the front. Tesla uses string inverters now without optimizers, so having only 3 panels on a plane is less than ideal. It means they will probably string them with the south-facing panels, which will lower efficiency.

Or try and push them to try and fit the 3 panels on the south-facing plane. Looks like there's enough room if you shift the array left.
 
I would shift 2 of the west-facing panels to the front of the house and drop the third, or shift all 3 to the front. Tesla uses string inverters now without optimizers, so having only 3 panels on a plane is less than ideal. It means they will probably string them with the south-facing panels, which will lower efficiency.

Or try and push them to try and fit the 3 panels on the south-facing plane. Looks like there's enough room if you shift the array left.
Yeah. West and South are on the same 3.8 inverter. I did a time lapse of the area and both sections seemed evenly lit throughout the afternoon. Project sunroof likes the West side of my roof (3 panels) and pvwatts agrees with Tesla's estimate.
 

pdx_m3s

Active Member
May 18, 2019
1,563
1,411
Portland, OR
Yeah. West and South are on the same 3.8 inverter. I did a time lapse of the area and both sections seemed evenly lit throughout the afternoon. Project sunroof likes the West side of my roof (3 panels) and pvwatts agrees with Tesla's estimate.

If the west and south facing panels are on the same string, I believe the south facing panels will be operating less efficient until the west panels get more sun later in the day. This is because Tesla no longer uses panel optimizers. PVWatts does not take this into account. Shade is no problem with panels having bypass diodes, but I believe different orientations on the same string is suboptimal. Maybe @nwdiver can chime in.
 
Hi all, I'm looking for some feedback on the solar design we just received from Tesla.

We received our system design from Tesla today. Overall it looks pretty standard with a few exceptions that I was hoping to get some feedback on.

Our system is a 8.16kW system (Tesla’s medium size) consisting of 24 Hanwa Q-Cell panels, one Powerwall+ integrated battery & string inverter, and a Gateway2. As shown below, 20 of the 24 panels are in a 4x5 array on the east facing roof, and 4 panels form a 2x2 array on the west facing roof. We have a little shade on the east facing roof, mostly from two chimneys. The west facing roof, on the other hand, is almost completely shaded by trees from about noon onwards during the summer months.

Tesla Solar 1.JPG


So if I'm reading the schematics below correctly, the panels will be connected in two strings:
  • Two parallel strings of 10 panels each going into one MPPT (MP 1); these are on the front (east) roof of our house.
  • A single string of 4 panels going into a second MPPT (MP 2); this is on the rear (west) roof.
Tesla Solar 2.JPG


So here are my questions/concerns.
  1. I am concerned that the 4 panels on MP 2 won’t reach the minimum voltage of the inverter very often due to the shade. To address this, my thinking was to either (1) add TWO more panels to this array, bringing the total to six. Then at least the string should get above V_min more often; mostly in the winter months when the leaves are off the trees. Or (2), get rid of the 4 panels and just go with the 20 on the east roof. I’m leaning towards (1) because this will give us some more power, especially in winter months. I also know it is difficult to try to add panels later on.
  2. I’m wondering why the 20 panels are strung into two parallel strings of 10 panels each on MP 1, instead of the two strings each being on a separate MPPT? I believe the string inverter supports 4 MPPTs. So the only reason I can think of is to reduce the number of conductors coming off the roof to the inverter in the basement. Would there be any other reason for doing this?
I’ve asked the above questions to my advisor at Tesla, but in the meantime I was hoping for some unbiased feedbac from this group.

Thanks in advance for any advice.
 
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nwdiver

Well-Known Member
Feb 17, 2013
9,033
13,480
United States
Hi all, I'm looking for some feedback on the solar design we just received from Tesla.

We received our system design from Tesla today. Overall it looks pretty standard with a few exceptions that I was hoping to get some feedback on.

Our system is a 8.16kW system (Tesla’s medium size) consisting of 24 Hanwa Q-Cell panels, one Powerwall+ integrated battery & string inverter, and a Gateway2. As shown below, 20 of the 24 panels are in a 4x5 array on the east facing roof, and 4 panels form a 2x2 array on the west facing roof. We have a little shade on the east facing roof, mostly from two chimneys. The west facing roof, on the other hand, is almost completely shaded by trees from about noon onwards during the summer months.

View attachment 660407

So if I'm reading the schematics below correctly, the panels will be connected in two strings:
  • Two parallel strings of 10 panels each going into one MPPT (MP 1); these are on the front (east) roof of our house.
  • A single string of 4 panels going into a second MPPT (MP 2); this is on the rear (west) roof.
View attachment 660408

So here are my questions/concerns.
  1. I am concerned that the 4 panels on MP 2 won’t reach the minimum voltage of the inverter very often due to the shade. To address this, my thinking was to either (1) add TWO more panels to this array, bringing the total to six. Then at least the string should get above V_min more often; mostly in the winter months when the leaves are off the trees. Or (2), get rid of the 4 panels and just go with the 20 on the east roof. I’m leaning towards (1) because this will give us some more power, especially in winter months. I also know it is difficult to try to add panels later on.
  2. I’m wondering why the 20 panels are strung into two parallel strings of 10 panels each on MP 1, instead of the two strings each being on a separate MPPT? I believe the string inverter supports 4 MPPTs. So the only reason I can think of is to reduce the number of conductors coming off the roof to the inverter in the basement. Would there be any other reason for doing this?
I’ve asked the above questions to my advisor at Tesla, but in the meantime I was hoping for some unbiased feedbac from this group.

Thanks in advance for any advice.

It's unfortunate that you have shade on the West side... that's generally preferred to East. Well... it is what it is.

  1. Should be ok. I think the minimum startup voltage is ~60v
  2. That is dumb. I would request they run them separately. The extra wire is worth the cost.
 
I’m wondering why the 20 panels are strung into two parallel strings of 10 panels each on MP 1, instead of the two strings each being on a separate MPPT? I believe the string inverter supports 4 MPPTs. So the only reason I can think of is to reduce the number of conductors coming off the roof to the inverter in the basement. Would there be any other reason for doing this?
Basically saving wire.

I have a project in progress with a similar setup - 7 panels per string x 2 strings, put in parallel on the roof, then two wires running down and two MPPT channels put in parallel. I have asked that four wires be run down to the inverter so each string is on it's own MPPT channel and the advisor on the phone said that they only do that for panels on different roof planes. I plan on asking the install crew to run the 4 wires...
 
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