Solar Panels Design

[KHYE]

Hello, after 5 weeks of constantly bugging Tesla, they have finally sent me the design

I'm located in SoCal and with SCE, I ordered a 8.5kW + 1 PW. I was expecting that they will provide ore detailed design with location of PW ,wiring and conduit placement. They didn't mention if I need to upgrade my main panel (100 Amp), But all I got is this diagram with front of the house labeled incorrectly. Am I'm supposed to get more detailed design at permit stage?

It seems to me this is the best solar panel placement on my roof due to the rooftop ac and vents. Do you think it's worthwhile ($ Wise) to ask them to add another panel to the North roof? Or ask them to max out my roof? My annual usage is 7560 kwh, Tesla estimated the 20 panels would generate 12,737 kwh annually. I hope I can be self power throughout the day with the 1 power wall.

Thanks.

 

[CrazyNavi]

I hope you have better luck adding panels. Tesla refused to do that, as their system are pre-defined.

 

[SaveOurPlanet]

Hello, after 5 weeks of constantly bugging Tesla, they have finally sent me the design

I'm located in SoCal and with SCE, I ordered a 8.5kW + 1 PW. I was expecting that they will provide ore detailed design with location of PW ,wiring and conduit placement. They didn't mention if I need to upgrade my main panel (100 Amp), But all I got is this diagram with front of the house labeled incorrectly. Am I'm supposed to get more detailed design at permit stage?

It seems to me this is the best solar panel placement on my roof due to the rooftop ac and vents. Do you think it's worthwhile ($ Wise) to ask them to add another panel to the North roof? Or ask them to max out my roof? My annual usage is 7560 kwh, Tesla estimated the 20 panels would generate 12,737 kwh annually. I hope I can be self power throughout the day with the 1 power wall.

Thanks.



View attachment 721097

Being in SoCal your North facing roof is still quite productive in Spring and Summer but they may not be as good as the West facing pane, can you not add 3 more panels on the remaining West pane which looks empty now? The West facing helps the late afternoon and early evening hours. Didn't you send your main panels photos to Tesla? They should be able to do the load calc to determine if you need any panel upgrade, also ask if they would do a site survey before actual permit application. My biggest concern was my 125A service and Tesla never said a thing about upgrading, the site survey person took more photos of my main panel and sub-panel. He even went over all possible PW location with me and told me that I can tell the install crew where I want them. Our daily consumption is around 18-20 kWh when we are home and I found 1 PW would generally cover our self-powered mode 99% of the days so with 2 PWs and use no more than 50% of capacity everyday. I am close to the coast so sometimes we would not see the sun of 2 or 3 days straight, thus the 2 PWs.

 

[KHYE]

Being in SoCal your North facing roof is still quite productive in Spring and Summer but they may not be as good as the West facing pane, can you not add 3 more panels on the remaining West pane which looks empty now? The West facing helps the late afternoon and early evening hours. Didn't you send your main panels photos to Tesla? They should be able to do the load calc to determine if you need any panel upgrade, also ask if they would do a site survey before actual permit application. My biggest concern was my 125A service and Tesla never said a thing about upgrading, the site survey person took more photos of my main panel and sub-panel. He even went over all possible PW location with me and told me that I can tell the install crew where I want them. Our daily consumption is around 18-20 kWh when we are home and I found 1 PW would generally cover our self-powered mode 99% of the days so with 2 PWs and use no more than 50% of capacity everyday. I am close to the coast so sometimes we would not see the sun of 2 or 3 days straight, thus the 2 PWs.

Thanks for your feedback. Yea, I can ask them to move the 2 north panels to the west pane if they refuse to add additional panels. I sent pictures of my main panels and subpanels to them. They never say anything. My avg daily usage is 18.23 kWh, really hope that 1 PW will cover it.

I've asked for site survey several times before getting the initial design, they said no need.

 

[CrazyNavi]

Thanks for your feedback. Yea, I can ask them to move the 2 north panels to the west pane if they refuse to add additional panels. I sent pictures of my main panels and subpanels to them. They never say anything. My avg daily usage is 18.23 kWh, really hope that 1 PW will cover it.

I've asked for site survey several times before getting the initial design, they said no need.

You Probably want another PW. don't look only your average but check on your peak-days. In the summer when your AC is running and you are at home cooking or running the dryer, also having a little extra store for backup isn't a bad thing. Adding another PW later will be a lot more expensive and time consuming. With the 26% tax credit and already including in the installation isn't a bad idea. I regret not going with 3

 

[SaveOurPlanet]

Thanks for your feedback. Yea, I can ask them to move the 2 north panels to the west pane if they refuse to add additional panels. I sent pictures of my main panels and subpanels to them. They never say anything. My avg daily usage is 18.23 kWh, really hope that 1 PW will cover it.

I've asked for site survey several times before getting the initial design, they said no need.

You may want to do a more accurate projection of how much you need during non-production hours, download your utility usage for 1 year and add up how much you use daily, you need to pick a few highest usage days. When I did mine, I estimated that I get the most usable sunlight in May and June when I will get energy production from 7:00am to 6:30pm, so I added up how many kWh I use from 6:00pm to 7:30am the next day and that was baseline for least demand from the PW. My lowest usable sunlight will give me energy production from 8:30am to 3:00pm thus I calculated how many kWh I use from 2:30pm to 9:00am the next day and that gives me the baseline for the most demand from the PW. Your most likely won't be self-powered for more than 60% during the Winter months but you can always count on NEM credits to even things out. I do agree 2 PWs is best for you but that is only if you are comfortable with the finance, don't think in terms of ROI, but you will feel a lot better if energy independence is what you want.

One thing though, I'm wondering why Tesla would not fill out all your West facing panes, do you have tall trees in that direction or are you in a valley where sunset comes earlier for you? I remember during my design phase I went back and forth with Tesla but we did not talk in terms of orientation, panels or solar cells (I ended up with solar roof) but the bottom line was how many kWh annual production I want and their final design was based on that.

 

[KHYE]

You Probably want another PW. don't look only your average but check on your peak-days. In the summer when your AC is running and you are at home cooking or running the dryer, also having a little extra store for backup isn't a bad thing. Adding another PW later will be a lot more expensive and time consuming. With the 26% tax credit and already including in the installation isn't a bad idea. I regret not going with 3

Another PW would be nice and ideal but everything is out of my pocket since I can't get the SGIP rebate. The only thing I have to run is AC but I will try to minimize its usage. Stove, oven, dryer, furnace and water heater are all gas. I have also installed a wholehouse fan myself and my AC usage is way less now in the evenings unless it's very humid outside.

 

[yblaser]

There might be an issue with the small west facing roof area and setback requirements. It looks like a panel would just fit in there, but may violate the setback requirement.

You can request the detailed design from Tesla once it is ready to submit for permits. They will not provide it to you automatically.

 

[KHYE]

I hope you have better luck adding panels. Tesla refused to do that, as their system are pre-defined.

I actually called them to check about adding one more panel to the north pane, they said it's possible but will take another several weeks to update the design in my account Due to fire set back and their mounting system, they said they can't add anymore panels to the west pane.

 

[KHYE]

There might be an issue with the small west facing roof area and setback requirements. It looks like a panel would just fit in there, but may violate the setback requirement.

You can request the detailed design from Tesla once it is ready to submit for permits. They will not provide it to you automatically.

You are correct, they won't add panels to west pane due to the setback. They said they will send schematics after I approve the initial design.

 

[KHYE]

You may want to do a more accurate projection of how much you need during non-production hours, download your utility usage for 1 year and add up how much you use daily, you need to pick a few highest usage days. When I did mine, I estimated that I get the most usable sunlight in May and June when I will get energy production from 7:00am to 6:30pm, so I added up how many kWh I use from 6:00pm to 7:30am the next day and that was baseline for least demand from the PW. My lowest usable sunlight will give me energy production from 8:30am to 3:00pm thus I calculated how many kWh I use from 2:30pm to 9:00am the next day and that gives me the baseline for the most demand from the PW. Your most likely won't be self-powered for more than 60% during the Winter months but you can always count on NEM credits to even things out. I do agree 2 PWs is best for you but that is only if you are comfortable with the finance, don't think in terms of ROI, but you will feel a lot better if energy independence is what you want.

One thing though, I'm wondering why Tesla would not fill out all your West facing panes, do you have tall trees in that direction or are you in a valley where sunset comes earlier for you? I remember during my design phase I went back and forth with Tesla but we did not talk in terms of orientation, panels or solar cells (I ended up with solar roof) but the bottom line was how many kWh annual production I want and their final design was based on that.

They won't add panels to west pane due to the setback. Adding one more panel to the North pane is ok but they will need several more weeks to update the design in my account I was able to get them to agree to a site survey, which they scheduled for this Fri.

Wondering if it's better to approve the design and move on or wait a few more weeks to get the design updated with one additional panel in the north pane. Sure want to get PTO before NEM 3.0 kicks in (supposedly in Jan 2022?).

 

[SaveOurPlanet]

I think you will be fine with the current design if your annual consumption is 7560 kwh and Tesla estimate is 12,737 kWh. Their engineers are not as stupid as some people make them out to be. The only thing is the PW but if you are flexible to manage your consumption then you are fine. I also have to pay for my own PWs but totally out of feeling good about energy independence especially I do not want to hear my wife complaining why she cannot bake for 3 hours when the sun is setting.

Since you have a wide margin between what you use and what Tesla estimates I would not bother with that one extra panel. Not sure when NEM 3 would actually happen but why wait?

During the site survey do discuss possible PW and inverter location, at least you know what is possible or not. You are a bit warmer than us so I would try to keep the PW inside the garage and inverter off the South, keep it indoor is even better if possible.

 

[jboy210]

I would not bother adding another panel to the North. You will find a North-facing panel does not have that much of an impact on your annual production and also only produces much around the solar peak of June 21.

You might be better adding another Powerwall to extend the amount of kWh you can store so you can use more of your solar power instead of buying power in the peak. Also, with one Powerwall they may need to create a critical loads-only panel that would exclude backing up big power using items like A/C and ovens, etc.

Regarding a more detailed layout including conduit placement, etc. we never received anything like that. We were home when they installed the system and worked with them to define that in real-time. Same with the precise placement of the Powerwalls. I think this works best since we are picky about how things look and wanted to see where things would look before they are installed.

 

[h2ofun]

I would not bother adding another panel to the North. You will find a North-facing panel does not have that much of an impact on your annual production and also only produces much around the solar peak of June 21.

You might be better adding another Powerwall to extend the amount of kWh you can store so you can use more of your solar power instead of buying power in the peak. Also, with one Powerwall they may need to create a critical loads-only panel that would exclude backing up big power using items like A/C and ovens, etc.

Regarding a more detailed layout including conduit placement, etc. we never received anything like that. We were home when they installed the system and worked with them to define that in real-time. Same with the precise placement of the Powerwalls. I think this works best since we are picky about how things look and wanted to see where things would look before they are installed.

Powerwall, if you have money to burn. Panels, get as many as you can fit, since adding later is just about impossible

 

[KHYE]

So, Tesla just finished the site survey. I was surprised that the surveyor came with a panels max out design. They have added 4 additional panels, this brings 20 panels to 24 panels and 8.5kw to 10.2 kw.

I was told by the advisor that placing additional panels in area B is not possible, somehow now it's possible Now I have to decide if I should proceed with the new design.

Here is the design that he just showed me:

I checked with him whether a service panel upgrade (100 amp) is needed, he doesn't think so but it's up to the engineering team. Then I asked if I need to install EV charger later, he said in that case, it might be needed to be upgraded.

 

[CrazyNavi]

So, Tesla just finished the site survey. I was surprised that the surveyor came with a panels max out design. They have added 4 additional panels, this brings 20 panels to 24 panels and 8.5kw to 10.2 kw.

I was told by the advisor that placing additional panels in area B is not possible, somehow now it's possible Now I have to decide if I should proceed with the new design.

Here is the design that he just showed me:

View attachment 721896
I checked with him whether a service panel upgrade (100 amp) is needed, he doesn't think so but it's up to the engineering team. Then I asked if I need to install EV charger later, he said in that case, it might be needed to be upgraded.

well you are freaking lucky! Make sure they share the panel spec, and they didn't switch to old panels which were 24 for 8.16kWh

 

[KHYE]

well you are freaking lucky! Make sure they share the panel spec, and they didn't switch to old panels which were 24 for 8.16kWh

Yea, i was surprised as well. These are the new and bigger panels. Now, I also need to find out if SCE can limit the amount of power they buy back since I will be generating way more than I will use. Some people have reported that has happened.

 

[SaveOurPlanet]

You should figure how many amps you plan to install for EV charging and let them know so they would include it in their load calc. You probably would need at least 30A 240V at the minimum. Also they may slap big red "do not add loads" stickers in all the load centers or panels so make sure you can add something after the fact (even though the Tesla tech told me anyone that knows what they are doing should be able to do so).

 

[KHYE]

You should figure how many amps you plan to install for EV charging and let them know so they would include it in their load calc. You probably would need at least 30A 240V at the minimum. Also they may slap big red "do not add loads" stickers in all the load centers or panels so make sure you can add something after the fact (even though the Tesla tech told me anyone that knows what they are doing should be able to do so).

Thanks for the tips, I have no idea what is needed. I don't have an EV yet but might get one down the road,

 

[wwhitney]

You will find a North-facing panel does not have that much of an impact on your annual production and also only produces much around the solar peak of June 21.

The extent to which that is true depends heavily on the roof pitch. For comparison, here are the geometric factors (cosine of angle) for a due north facing roof at 34 degrees latitude (LA), on the equinox and on the summer solstice, for a few slopes:

1 in 12: arctan(1/12) = 5 degrees; equinox angle = 39 degrees, 78%; summer solstice angle = 15 degrees, 97%
4 in 12: arctan(4/12) = 18 degrees; equinox angle = 52 degrees, 62%; summer solstice angle = 28 degrees, 88%
8 in 12: arctan(4/12) = 34 degrees; equinox angle = 68 degrees, 53%; summer solstice angle = 44 degrees, 72%
12 in 12: arctan(12/12) = 45 degrees; equinox angle = 79 degrees, 19%; summer solstice angle = 55 degrees, 57%

Of course, that's for solar noon, things will be worse the rest of the day. And the above has compounded rounding errors.

Cheers, Wayne