Post Your Tesla Solar Layout

[pdx_m3s]

I am in the process of getting 12kW system installed with 2 powerwalls... Can someone please advise on the following 2 items:

• after the design was approved and all paperwork completed, now Tesla advised me that it will take another 6 weeks before Utility (ComEd) to approves the install... only after they approve, then Tesla can schedule the installation... currently they are about 30 from scheduling to actual install date... this puts me in the winter territory in Chicago plus with all the turmoil in the country. Does anyone have any experience with expediting these timelines?
• The following was my assumption but I recently started questioning myself: based on my solar system estimated output, I will be at 60% of typical power requirements with the balance of electricity provided by Utility. If my PWs are fully charged and the utility power goes out, my home will be draining PWs. Here is the question: will the power produces by my solar panels will be purely dedicated to charging my PWs (I do not anticipate any excess power produced). Just wanted to make sure I can be somewhat off the grid.

Thank you

To your last point, if the utility power goes out, the gateway will automatically shut off power from being able to go from your solar to the grid, and therefor all of it will go to your PWs. Depending on weather and how you manage your loads, you should be able to go off grid for a little while.

 

[BrettS]

after the design was approved and all paperwork completed, now Tesla advised me that it will take another 6 weeks before Utility (ComEd) to approves the install... only after they approve, then Tesla can schedule the installation... currently they are about 30 from scheduling to actual install date... this puts me in the winter territory in Chicago plus with all the turmoil in the country. Does anyone have any experience with expediting these timelines?

Unfortunately there’s not a lot that can be done here. There are a lot of moving pieces and a lot of different entities are involved. Tesla, your utility, your local city or county for building permits, etc. And to make things worse, each area and each utility has different requirements. For example, my utility didn’t need to approve the project before it was installed. But you’re stuck with your utility and their requirements. About the only advice I can give you is to try to contact your utility and see if you can get an estimate from them on how long it takes to provide their approval. You can also ask them if they have all the info they need from Tesla as we have seen examples in the past where projects get stuck in kind of a limbo state where tesla thinks they are waiting for the utility and the utility thinks they are waiting for tesla.

The following was my assumption but I recently started questioning myself: based on my solar system estimated output, I will be at 60% of typical power requirements with the balance of electricity provided by Utility. If my PWs are fully charged and the utility power goes out, my home will be draining PWs. Here is the question: will the power produces by my solar panels will be purely dedicated to charging my PWs (I do not anticipate any excess power produced). Just wanted to make sure I can be somewhat off the grid.
Thank you

I’m not quite sure what you’re asking here. The powerwalls can only be charged by solar, so depending on how you have your powerwalls configured the system may send your solar power to the powerwalls to charge them first and allow your house to run off the grid. Once the powerwalls have charged then it will power your house with solar power and send the excess to the grid.

During an outage your house will be prioritized and any available solar power will go to powering your house first, with any excess going to charging the powerwalls. You should be able to operate off grid in some capacity during an extended power failure, but because your system will only be able to provide about 60% of your normal usage then you will want to significantly cut back on your power usage during an outage so you don’t run out of power during the night before the sun comes back up.

 

[TC_HTX]

Crew showed up very promptly this morning ta about 7:15 to get start on work. If you guys are on here, I'm so sorry about my cars. The electricians needed me to move my car and of course the locks decided to not work (thanks Chevy for your reliability!). Thankfully the crew is great and everyone is pretty friendly so they are just working around it. Had to make a few changes due to the position of the inverter not being on an exterior wall - my garage only has 2 exterior walls - but they're making it work.

 

[TC_HTX]

Update: The layout from Tesla wasn't spot on and they weren't able to fit all the panels. Down 4 panels so dropping from an 8.16kW system to a 6.8kW system. Definitely made me glad we didn't do powerwalls. 8.16kW would have been right around 100% daily use. 6.8 is still better than nothing, but wouldn't be sufficient to charge the powerwalls with

 

[miimura]

Update: The layout from Tesla wasn't spot on and they weren't able to fit all the panels. Down 4 panels so dropping from an 8.16kW system to a 6.8kW system. Definitely made me glad we didn't do powerwalls. 8.16kW would have been right around 100% daily use. 6.8 is still better than nothing, but wouldn't be sufficient to charge the powerwalls with

The bold part makes no sense to me. I have two PWs and only 4.3kW solar. It works great for me. However, I don't know what your expectations are from the PW system.

 

[TC_HTX]

The bold part makes no sense to me. I have two PWs and only 4.3kW solar. It works great for me. However, I don't know what your expectations are from the PW system.

It is going to depend on your usage, location, etc. Based on my usage history, the 6.8kW system should meet 75-100% of my needs during the day. If we are using all that is generated then there's not much left to go back to PW. Granted, the PW would be just a novelty for me. Net metering, no TOU charges, etc.

 

[BrettS]

It is going to depend on your usage, location, etc. Based on my usage history, the 6.8kW system should meet 75-100% of my needs during the day. If we are using all that is generated then there's not much left to go back to PW. Granted, the PW would be just a novelty for me. Net metering, no TOU charges, etc.

But keep in mind that your house uses power 24 hours a day, but solar is only generated during daylight hours. For example, the other day my house used 50kWh and my solar generated 50kWh, but my house was only able to directly use 20kWh of solar power. The other 30kWh was used by my house during the evening and night.

So with powerwalls my house would use 30kWh from the powerwall overnight, then during the day 20kWh from the solar system would go directly to the house and 30kWh would go to the powerwalls to recharge them. I would still be generating only 100% of my usage, but it’s plenty to keep my powerwalls charged. On days where I only generated 75% of my usage the powerwalls might not fully charge, but the system would draw the extra from the grid to power my house and it would keep the powerwalls above the reserve level so that I would still have some power available in case of an outage.

You don’t need more solar power than your house uses to recharge powerwalls, because your solar will generate more power than your house can use directly during the day.

Edited to add: With no net metering and no TOU rates, then powerwalls definitely won’t make a lot of financial sense. They would be useful for backup power in the event of an outage, but that’s about it. My point was just that you don’t need more solar power than your house uses just to get powerwalls.

 

[miimura]

It is going to depend on your usage, location, etc. Based on my usage history, the 6.8kW system should meet 75-100% of my needs during the day. If we are using all that is generated then there's not much left to go back to PW. Granted, the PW would be just a novelty for me. Net metering, no TOU charges, etc.

This makes sense. If you have full net metering, don't have punitive TOU rates, and don't need the backup power function, then don't get the Powerwalls. It's as simple as that.

 

[zƬesla]

But keep in mind that your house uses power 24 hours a day, but solar is only generated during daylight hours. For example, the other day my house used 50kWh and my solar generated 50kWh, but my house was only able to directly use 20kWh of solar power. The other 30kWh was used by my house during the evening and night.

You need the new panels that PV generate during the day and the other side absorbs heat refraction at night

 

[TC_HTX]

But keep in mind that your house uses power 24 hours a day, but solar is only generated during daylight hours. For example, the other day my house used 50kWh and my solar generated 50kWh, but my house was only able to directly use 20kWh of solar power. The other 30kWh was used by my house during the evening and night.

So with powerwalls my house would use 30kWh from the powerwall overnight, then during the day 20kWh from the solar system would go directly to the house and 30kWh would go to the powerwalls to recharge them. I would still be generating only 100% of my usage, but it’s plenty to keep my powerwalls charged. On days where I only generated 75% of my usage the powerwalls might not fully charge, but the system would draw the extra from the grid to power my house and it would keep the powerwalls above the reserve level so that I would still have some power available in case of an outage.

You don’t need more solar power than your house uses to recharge powerwalls, because your solar will generate more power than your house can use directly during the day.

Edited to add: With no net metering and no TOU rates, then powerwalls definitely won’t make a lot of financial sense. They would be useful for backup power in the event of an outage, but that’s about it. My point was just that you don’t need more solar power than your house uses just to get powerwalls.

I certainly understand that. But running PVWatts and comparing my hourly usage I only lightly overproduce. I looked at August 15th and at noon I used 4.5kWh and the anticipated production from noon to 1PM on a typical August 15th in my area is 4.8kWh. In general, my solar will produce what I use during the day and not much more. This doesn't leave much excess to go to PW or grid which is why I may end up switching to a free nights plan.

For reference, during the summer I use about 75kWh in a 24h period, but will anticipate producing only about 50kWh which matches roughly with my daytime usage. I have to wait and see the data, but more likely than not there wouldn't be much left to charge up powerwalls anyway.

 

[wjgjr]

I certainly understand that. But running PVWatts and comparing my hourly usage I only lightly overproduce. I looked at August 15th and at noon I used 4.5kWh and the anticipated production from noon to 1PM on a typical August 15th in my area is 4.8kWh. In general, my solar will produce what I use during the day and not much more. This doesn't leave much excess to go to PW or grid which is why I may end up switching to a free nights plan.

For reference, during the summer I use about 75kWh in a 24h period, but will anticipate producing only about 50kWh which matches roughly with my daytime usage. I have to wait and see the data, but more likely than not there wouldn't be much left to charge up powerwalls anyway.

The one big point to me is that it is not necessary to compare production to home load to determine whether you can charge PWs - the only thing to look at is production. That is to say, if you wanted, you could choose to get that 4.5 kWh from the grid from noon-one and also increase the level of your PWs by 4.8 kWh during that time - the only limits here are the charging limit per PW and that generally you cannot charge PWs from the grid. But you can charge your PWs from solar while at the same time pulling from the grid for home load (at least in most cases - may be some odd utility rules that exist.)

In your situation, where backup power is not a goal/concern, full net metering, and no TOU pricing, I absolutely agree there is no reason for you to get PWs - just clarifying that they can still be charged even when solar doesn't cover home usage.

As a side note - it may not be as big an issue depending on where you are and how variable your weather is, but where I am, the PVWatts daily/hourly numbers are not a particularly useful data point because each day seems to be modeled independently. As a result, on 9/12, my estimate power is 0.8W from noon-1, and then on 9/13 the estimate is 2.7W. Over the course of the month it mostly averages out, but the data for a given day has huge variation.

 

[BrettS]

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I certainly understand that. But running PVWatts and comparing my hourly usage I only lightly overproduce. I looked at August 15th and at noon I used 4.5kWh and the anticipated production from noon to 1PM on a typical August 15th in my area is 4.8kWh. In general, my solar will produce what I use during the day and not much more. This doesn't leave much excess to go to PW or grid which is why I may end up switching to a free nights plan.

Fair enough, but if you are expecting to be consuming solar power as it is generated you need to use it as it is generated, which isn’t an average. So in your example from noon to 1PM your solar system might produce 4.8kWh. This means that assuming there are no clouds the system will be producing 4.8kW for one hour. However, even though your house may average 4.5kWh, that doesn’t necessarily mean that it will draw 4.5kW for one hour.

Instead your house might draw 2kW for 30 minutes, and then your air conditioner might come on and your house will then draw 7kW for 30 minutes. Over that hour your house would have averaged 4.5kWh and even though your solar system produced 4.8kWh over that same time period you only would have been able to directly use 3.4Wh. You would have sent 1.4kWh to the grid (during the first half hour) and you would have needed to draw 1.1kWh from the grid (during the second half hour)

As long as you have net metering, then this is not a problem, since the net will be .3kWh to the grid, but it’s my understanding that there aren’t a lot of net metering options in TX.

With a powerwall the system could have used that excess 1.4kWh that you would have sent to the grid to charge the powerwall during the first 30 minutes, then pulled back 1.1kWh during the next 30 minutes.

The thing to remember is that (other than minor efficiency losses) the powerwalls aren’t a net consumer or a net generator of power. They won’t allow you to get more power from your solar system and you won’t need to install a bigger solar system just to use powerwalls. They simply allow you to take the power that you are generating and use it at a different time. This is helpful because solar power can only be generated during certain times of the day and often is generated in excess during those times.

Obviously that example is a bit oversimplified, but the point is that your home usage fluctuates a lot when you consider things like air conditioner or refrigerator compressors cycling on and off and other appliances being used. Even things like electric ovens and driers will cycle power to their heating elements when they are running, so you can’t really look at averages if you’re trying to figure out how much solar power you can directly consume. You need to consume that power in the moment that it is produced or use it to charge a powerwall or send it back to the grid.

 

[TC_HTX]

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Fair enough, but if you are expecting to be consuming solar power as it is generated you need to use it as it is generated, which isn’t an average. So in your example from noon to 1PM your solar system might produce 4.8kWh. This means that assuming there are no clouds the system will be producing 4.8kW for one hour. However, even though your house may average 4.5kWh, that doesn’t necessarily mean that it will draw 4.5kW for one hour.

Instead your house might draw 2kW for 30 minutes, and then your air conditioner might come on and your house will then draw 7kW for 30 minutes. Over that hour your house would have averaged 4.5kWh and even though your solar system produced 4.8kWh over that same time period you only would have been able to directly use 3.4Wh. You would have sent 1.4kWh to the grid (during the first half hour) and you would have needed to draw 1.1kWh from the grid (during the second half hour)

As long as you have net metering, then this is not a problem, since the net will be .3kWh to the grid, but it’s my understanding that there aren’t a lot of net metering options in TX.

With a powerwall the system could have used that excess 1.4kWh that you would have sent to the grid to charge the powerwall during the first 30 minutes, then pulled back 1.1kWh during the next 30 minutes.

The thing to remember is that (other than minor efficiency losses) the powerwalls aren’t a net consumer or a net generator of power. They won’t allow you to get more power from your solar system and you won’t need to install a bigger solar system just to use powerwalls. They simply allow you to take the power that you are generating and use it at a different time. This is helpful because solar power can only be generated during certain times of the day and often is generated in excess during those times.

Obviously that example is a bit oversimplified, but the point is that your home usage fluctuates a lot when you consider things like air conditioner or refrigerator compressors cycling on and off and other appliances being used. Even things like electric ovens and driers will cycle power to their heating elements when they are running, so you can’t really look at averages if you’re trying to figure out how much solar power you can directly consume. You need to consume that power in the moment that it is produced or use it to charge a powerwall or send it back to the grid.

Very good points, once I ditched the idea of the powerwall for my usage I didn't think about it this much.

Thankfully I'm in Houston where our energy market is deregulated. I have net metering available, and will run it for a few months to see what ends up making the most sense between net metering or a free nights plan.

 

[AnotherMike]

So I just received my roof layout, only 2 days after placing my order for an 8.16kw system. My roof layout is pretty simple, but I do have some concerns about shading. Here is the layout they put together:



There are 2 large trees on the west corner of my property, here is a picture of shading from them on my roof at 5:20pm:



So a couple things:

1) Does shading later in the afternoon/ early evening matter that much or is this mostly past peak production times?

2) Does it make sense to move, say, half of the panels to the NE roof where there is no shade? Running numbers through PVWatts a 50/50 split would produce around 11000kWh vs around 12500 putting it all on the SW roof. Note that does not account for any shade on the SW roof

3) Tesla's proposal was for a Delta string inverter, which I thought they were not using anymore. Does anyone prefer those, or should I ask them to change to SolarEdge especially given the shading?

Another option would be to get the tree nearest my house removed - it is crazy overgrown right now and I'm not sure it's even safe - need to get an arborist out. Maybe I just need to do this first then decide on the layout. Here's a picture of the trees in question:



Thanks in advance for any input!

 

[BrettS]

So I just received my roof layout, only 2 days after placing my order for an 8.16kw system. My roof layout is pretty simple, but I do have some concerns about shading. Here is the layout they put together:

The layout certainly looks good

There are 2 large trees on the west corner of my property, here is a picture of shading from them on my roof at 5:20pm:

So a couple things:

1) Does shading later in the afternoon/ early evening matter that much or is this mostly past peak production times?

The shading definitely looks like it would be an issue. At the point in the picture I suspect you would be getting very little, if any production due to the shading. It would also start cutting into your production well before that as the shade started moving across the roof. Late afternoon will be past peak production time, but 4:00-5:00 will still be a decent hour for production and 5:00-6:00 should have some production as well

2) Does it make sense to move, say, half of the panels to the NE roof where there is no shade? Running numbers through PVWatts a 50/50 split would produce around 11000kWh vs around 12500 putting it all on the SW roof. Note that does not account for any shade on the SW roof

NE is really not a great orientation for panels and by moving half your panels you lose 12% of your annual production. That’s pretty significant. But that said, I’m not sure how much production you would lose with your shading either. It definitely could be in the 12% range or maybe even more.

3) Tesla's proposal was for a Delta string inverter, which I thought they were not using anymore. Does anyone prefer those, or should I ask them to change to SolarEdge especially given the shading?

It’s weird. It seems like almost all the quotes we see are solaredge inverters, but every once in a while there’s a delta thrown in. It seems like they use delta much more often with the solar roof, but even with panels we see one once in a while. I don’t know why they decide to go delta occasionally.

Another option would be to get the tree nearest my house removed - it is crazy overgrown right now and I'm not sure it's even safe - need to get an arborist out. Maybe I just need to do this first then decide on the layout. Here's a picture of the trees in question:

Honestly that’s probably the best option in terms of production, but I hate to see a tree come down. I’m not sure you have a lot of great options though.

 

[zƬesla]

1) Does shading later in the afternoon/ early evening matter that much or is this mostly past peak production times?

The shading definitely looks like it would be an issue. At the point in the picture I suspect you would be getting very little, if any production due to the shading. It would also start cutting into your production well before that as the shade started moving across the roof. Late afternoon will be past peak production time, but 4:00-5:00 will still be a decent hour for production and 5:00-6:00 should have some production as well

Do you also need to be concerned with earlier shading in winter?

 

[Dave EV]

Honestly that’s probably the best option in terms of production, but I hate to see a tree come down. I’m not sure you have a lot of great options though.

Yeah, I agree that the tree appears to be way too big to be that close to the house. It's likely to be causing other issues - foundation, etc. No one likes to see trees go, but I would closely inspect for other issues that the tree may be causing.

BrettS did a great job of laying out the pros and cons - the NE roof may be just as productive given the shade issues. I see a garage in the picture - can that roof be used? Maybe use the SW roof on the garage and the NE roof on the house. Getting power to the garage may be more expensive, though.

 

[CrazyRabbit]

56 enphase iq7+ q-cell 320 watt panels. Right side of image is north.

 

[wjgjr]

Yeah, I agree that the tree appears to be way too big to be that close to the house. It's likely to be causing other issues - foundation, etc. No one likes to see trees go, but I would closely inspect for other issues that the tree may be causing.

This is why I would say get rid of the tree, even without solar. The proximity of the trunk to the house and the number of branches directly overhanging the roof would concern me. Perhaps look to plant a tree somewhere else on the property to compensate, if possible.

 

[SMAlset]

@AnotherMike, Looks to be a California Pepper Tree (Schinus molle). Get rid of it. We had a number of them in our condo complex and apart from the heavy debris they produce (so think about this on roof and in gutters) their roots lifted and destroyed walkway stairs that had to be ripped up and repoured after they pulled out all the pepper trees. Our current HOA removed the ones that the developer planted that were affecting our walkways already. Some species grow up to 5 stories tall. Really more a "park" tree anyway.

The tree is also listed as invasive in California and with "high root damage". You'll find it under "Trees not Recommended by TreePeople but on the Street Tree List" for the City of Los Angeles. https://www.marvista.org/productphotos/LA-City-Approve-Street-Trees.pdf