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Does this system design make sense?

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I just received my system design and I'm a little surprised but I'm no expert. Can I get a look over by the group here?

It looks like they are doing 30 panels, 30 microinverters and 2 Powerwalls to create a 12kW system size, estimating 16,536kWh annual consumption. I don't know why they are setting a goal of 24,500kWH seeing that my consumption from September 1, 2021 to July 31, 2022 was 7,312kWh. I've oversized my system knowing I'm going to use more energy and add a EV in the future, but don't know where 24,500kWh is coming from.

Few questions I had on initial design

1. I was surprised that they are having all the equipment outside. I was thinking they were going to have it inside the garage along the same wall they are diagrammed. They told me they couldn't do that?
2. In the bottom left corner, you can see they have one of my batteries not behind the fence (left side of fence is open to front of house, right side of fence is backyard). Can't they stack both batteries to keep the hardware behind the fence and not accessible from someone just walking along the street?
3. I have my main panel and then a sub panel inside the garage. It looks like they are installing another sub panel outside (100A ESS Sub Panel). Is that typical? They said they are doing this because the batteries will be tied to that and back up everything in there?
4. You will see in the Critical Loads Panel Schedule, they are saying customer needs to install soft started on all AC units and needs to turn off all loads above 40A during outage. Doesn't this defeat the purpose of having the battery running AC during outage or do most people don't back up their AC?

The contract system was shy of $60K before tax credit. They are charging now an additional $2000 for whole home transfer and $1500 for equipment location.

Maybe I'm dumb, but does anything stand out as "strange" here?
 

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1. There are fights with putting systems in garages (and a lot more red tape). Its much easier for an installer to put them outside. If you want it inside you may have to fight for it (if its even possible, im not a plans expert so not looking at your plan / attachment.

2. I dont know if stacking powerwalls is allowed under new code. I am thinking "no" but as I said I am not a code expert. They likely need to be 36 inches apart.

since you are talking micro inverters, this isnt tesla quoting this. The higher pricing is supposed to come with more customer service, so they should be available to answer some of these questions for you as well.
 
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They are charging now an additional $2000 for whole home transfer and $1500 for equipment location.
The installer/provider cannot make unilateral changes. This is only valid if the buyer also agrees to the change order or addendum. Going to a non-Tesla vendor should come with a greater level of support and communication. I’d say it’s their job to educate you and make sure your concerns are addressed. Good luck with your system!
 
I just received my system design and I'm a little surprised but I'm no expert. Can I get a look over by the group here?

It looks like they are doing 30 panels, 30 microinverters and 2 Powerwalls to create a 12kW system size, estimating 16,536kWh annual consumption. I don't know why they are setting a goal of 24,500kWH seeing that my consumption from September 1, 2021 to July 31, 2022 was 7,312kWh. I've oversized my system knowing I'm going to use more energy and add a EV in the future, but don't know where 24,500kWh is coming from.

Few questions I had on initial design

1. I was surprised that they are having all the equipment outside. I was thinking they were going to have it inside the garage along the same wall they are diagrammed. They told me they couldn't do that?
2. In the bottom left corner, you can see they have one of my batteries not behind the fence (left side of fence is open to front of house, right side of fence is backyard). Can't they stack both batteries to keep the hardware behind the fence and not accessible from someone just walking along the street?
3. I have my main panel and then a sub panel inside the garage. It looks like they are installing another sub panel outside (100A ESS Sub Panel). Is that typical? They said they are doing this because the batteries will be tied to that and back up everything in there?
4. You will see in the Critical Loads Panel Schedule, they are saying customer needs to install soft started on all AC units and needs to turn off all loads above 40A during outage. Doesn't this defeat the purpose of having the battery running AC during outage or do most people don't back up their AC?

The contract system was shy of $60K before tax credit. They are charging now an additional $2000 for whole home transfer and $1500 for equipment location.

Maybe I'm dumb, but does anything stand out as "strange" here?
If your consumption for the last 11 months was only 7,312 kWh then PG&E is going to have some concerns without justification for increased usage. You should ask the installer when they are using 24,500 kWh especially since they want you to note that the design is only 67% of the expectation. I'm surprised that they didn't split the panels so that there were some on the NW side to better catch the late afternoon soon when you need it for the AC, but there is a not about shading so that might be the reason.

You have two Powerwalls and each can handle 5kW or 10kW in total. At 240V that is 41.6A which is why they are noting that you can't draw more than 40A @ 240V. AC units when they start up have a high draw when it starts and then reduces. I also have two Powerwalls and my smaller AC is backed up, but the larger AC is not.
 
I just received my system design and I'm a little surprised but I'm no expert. Can I get a look over by the group here?

It looks like they are doing 30 panels, 30 microinverters and 2 Powerwalls to create a 12kW system size, estimating 16,536kWh annual consumption. I don't know why they are setting a goal of 24,500kWH seeing that my consumption from September 1, 2021 to July 31, 2022 was 7,312kWh. I've oversized my system knowing I'm going to use more energy and add a EV in the future, but don't know where 24,500kWh is coming from.

Few questions I had on initial design

1. I was surprised that they are having all the equipment outside. I was thinking they were going to have it inside the garage along the same wall they are diagrammed. They told me they couldn't do that?
2. In the bottom left corner, you can see they have one of my batteries not behind the fence (left side of fence is open to front of house, right side of fence is backyard). Can't they stack both batteries to keep the hardware behind the fence and not accessible from someone just walking along the street?
3. I have my main panel and then a sub panel inside the garage. It looks like they are installing another sub panel outside (100A ESS Sub Panel). Is that typical? They said they are doing this because the batteries will be tied to that and back up everything in there?
4. You will see in the Critical Loads Panel Schedule, they are saying customer needs to install soft started on all AC units and needs to turn off all loads above 40A during outage. Doesn't this defeat the purpose of having the battery running AC during outage or do most people don't back up their AC?

The contract system was shy of $60K before tax credit. They are charging now an additional $2000 for whole home transfer and $1500 for equipment location.

Maybe I'm dumb, but does anything stand out as "strange" here?
I'm not a solar expert; there are others here who have way more experience than I do who actually work in the field.

According to the plan that you posted, the PV production is actually estimated to be 16,500kWh/yr. Your first year average demand would be projected to be just under 8,000kWh, given your observed usage over the last 11 months. As you plan to buy an EV, with the "extra" 8,500 kWh per you would have (8500/25)*100 miles of capacity, or about 34,000 miles of charging per year. (Model 3 at 25kWh/100miles) It isn't clear from the plans where your installer got 24,500kWh of projected demand. Did you suggest a switch to heat pumps, a new electric dryer, ovens, more than one EV, or a pool...?

However, the plans also indicate shading issues with trees, chimney and roof obstructions, so your actual production is likely to be lower than the 16,500kWh/yr, especially as your roof is a southeast exposure, which will have more impact from morning overcast than a southwest facing roof.

Your AC unit (units?) is (are) likely to draw a huge amount at startup that could or will overwhelm two Powerwalls without a way to reduce the initial surge like a "soft start", and quite a bit while running. Not every AC can use "soft start" technology, so double check what your initial draw is (LRA on the nameplate), and whether your particular model can use a "soft start", which is not the same as a "hard start". If you want to keep your AC on, you will probably want more than two Powerwalls. Air conditioning is a huge energy sink, unless your home is exceptionally well insulated and sealed. Huge sink. There are folks here whose AC can drain a Powerwall in two and half hours.

I would enquire what the whole home transfer is. The power walls come with a Gateway that is a whole home transfer switch.

Given the disruptions in solar panels at the moment, the price doesn't seem that far out to me, but others who have gotten recent quotes may differ.

All the best,

BG
 
If your consumption for the last 11 months was only 7,312 kWh then PG&E is going to have some concerns without justification for increased usage. You should ask the installer when they are using 24,500 kWh especially since they want you to note that the design is only 67% of the expectation. I'm surprised that they didn't split the panels so that there were some on the NW side to better catch the late afternoon soon when you need it for the AC, but there is a not about shading so that might be the reason.

You have two Powerwalls and each can handle 5kW or 10kW in total. At 240V that is 41.6A which is why they are noting that you can't draw more than 40A @ 240V. AC units when they start up have a high draw when it starts and then reduces. I also have two Powerwalls and my smaller AC is backed up, but the larger AC is not.
The calculations come from estimated 8,300kWh for the year. Then added an additional 2,500 kWh once I get solar (I explained to them that my 8,300kWh usage was conservative as I rarely ran AC to be cautious of costs, etc. Then added an additional 3,000kWh for 2nd EV. That brought total future consumption to be ~13,900kWh or a 10.2kW system. I rather be "safe than sorry" so I went with the bigger 12kW system to future proof myself from anything else.

I'm also going to ask why the design has everything on the back side of the roof and not the NW (considering cosmetic > maximum efficiency?) They made a note about "shading issues" but here is a picture at 8 AM. I don't know what "shading issue" they are speaking of?

The whole purpose of my to get the batteries was to run solely off the batteries during PEAK power times. It gets the hottest here around 4 PM so AC was one of the key items I wanted to be able to run off the batteries. If I can't do that, then I should consider scrapping the batteries or reducing down to one?

IMG_6411.jpg
 
I'm also going to ask why the design has everything on the back side of the roof and not the NW (considering cosmetic > maximum efficiency?)
Best facing directions (in addition to azimuth angle and other factors) are: South, East-West, and North (least desirable).

Did you have a site visit in order for the installer to design your system? If not, it’s likely they used something like HelioScope to remotely design your system.
 
I'm surprised that they didn't split the panels so that there were some on the NW side to better catch the late afternoon sun when you need it for the AC, but there is a note about shading so that might be the reason.
If I did the calculation correctly, moving 6 panels to the NW side would increase summer time production after 4PM by 2kWh on sunny days without losing any total daily production. On the other hand, in December/January there is negligible late afternoon effect, but total daily production is reduced by around 4kWh (about 10% of the whole roof's production), again during sunny weather. Actual reduction in output during the winter will not be as severe, since some days don't have much sun.
 
I took some time to create my follow-up questions on their design. Anything else I'm missing?

  1. Why is the goal set for 24,500 kWh?
  2. Why is there a note saying shading issue due to roof, obstructions, trees and chimney when its a 2 story house with no tree obstruction.
  3. How many electrical panels are being installed? Currently existing, I have the main panel outside and a sub panel inside the garage. It looks like you are adding two more panels? What is the purpose and how does this impact my other panels?
  4. The diagram shows the Tesla Backup Gateway 2 and 200A Backup Panel inside the garage. Where in the garage is this located?
  5. The top left diagram shows a 125A Backup Panel inside the garage. What is this as I thought it was a 200A Backup Panel?
  6. I've seen many installs with the hardware inside the garage along the side wall. Why can we not do the same?
  7. I do not like how one of the batteries is exposed beyond the fence line, why can't we double stack the batteries so that both batteries are behind the fence line?
  8. Any reason why some panels were not split to be on NW roofline to capture later afternoon sun setting?
  9. Will usage be monitored through Enphase or Tesla app or both?
  10. The primary purpose of the batteries was to run off solar during the day and then draw from the batteries during PEAK time. This would include wanting to run AC. There is a note saying I cannot run any 40A loads from batteries, so does this defeat my goal of using batteries during PEAK time to prevent pulling from grid at PEAK time?
  11. Can you explain why there is an additional $2,000 whole home transfer cost and what that entails compared to the original quote?
  12. Can you explain why there is an additional $1,500 equipment location cost when all equipment is all based at the power meter?
 
I would probably stick with minimum 2 batteries vs. 1. I use AC during peak and can get through the on-peak hours, but don't crank the A/C to maximum low temps.

Can't predict how much you will need since that depends on other usage, but 1 battery seems costly by itself since all the work still has to be done whether 1 or 2 (or more batteries) and most install quotes I've seen isn't 'that' much more when adding an extra battery (or more panels, etc).

You will definitely have chimney shading looking at your diagram and the real picture throughout the day. I have 1 panel like that and it ALWAYS produces less daily.

As for why some can have it inside and some can't, that seems really random and depends on local jurisdictions. Laws are changing everywhere I've noticed and installers have more hassles/problems it seems getting them installed inside the garage now so like others have said, you might have to fight hard and understand your local laws if you really want them in the garage.
 
I'm also going to ask why the design has everything on the back side of the roof and not the NW (considering cosmetic > maximum efficiency?) They made a note about "shading issues" but here is a picture at 8 AM. I don't know what "shading issue" they are speaking of?
A lot of people who consider cosmetic > efficiency prefer not to put the panels on the front of the house. If they put panels on NW, isn't it visible by all your neighbors as well as cars coming down at least one street, maybe two? Vs being only visible standing near the back of your rear yard?

Plus it's not more efficient on NW anyways, less annual production. More peak period production sure, but with Powerwalls you can arbitrage TOU anyways, so why not go for more total production? And the SE orientation might allow you to fill the Powerwalls more (for more backup reserve) during winter than you would otherwise, whereas NW the Powerwalls could be getting full mid-day and you're just pushing the excess out to the grid for credits...

If aesthetics matter the most, I would remove 3-5 panels that are horizontally oriented or by themselves, rather than putting them on the street side. We had a 19-panel Enphase proposal when we installed, and ultimately cut 3 panels that were awkwardly oriented; sure I wish I had that extra production, but I'm sure the half of my neighbors that have to see mine every day appreciate it better...
 
Do we know if the IQ8 inverters will allow charging of the batteries from the solar system when there is an outage of the grid? It looks as though with IQ7, when the grid was down, the solar system was down too and wouldn't generate anything even if sun was up?
 
Wanted to add we have some panels on the West side angled to the late afternoon sun and those tend to generate as much as the South facing ones so if you don't care about looks, having them there vs. NW would be a lot better. Even a few seems to help us.
 
Do we know if the IQ8 inverters will allow charging of the batteries from the solar system when there is an outage of the grid? It looks as though with IQ7, when the grid was down, the solar system was down too and wouldn't generate anything even if sun was up?
Kind of; IQ8 are capable of grid formation and power absent the grid. This only matters if you don't have Powerwalls. The Gateway and Powerwalls will form a grid in the absence of the IOU grid, allowing the PV to charge the batteries, and when full taper the solar charge to zero.
 
Kind of; IQ8 are capable of grid formation and power absent the grid. This only matters if you don't have Powerwalls. The Gateway and Powerwalls will form a grid in the absence of the IOU grid, allowing the PV to charge the batteries, and when full taper the solar charge to zero.
I think it's a bit more accurate to say the Gateway is capable of grid formation, in this case it's the Tesla Gateway, but also true for Enphase's gateway. With either gateway, I think any older Enphase micro can also produce power with the simulated grid (differences are more how limited in curtailment options).

Of course the gateway is there because there are batteries in this installation. I think IQ8 is not capable of grid formation by itself in a solar-only install. But Enphase gateway can be added without batteries to allow IQ8 to generate power, though it sounds like it doesn't work well - and anecdotal quote by my friend a few months ago, $10K+ just to add the gateway without batteries....

But anyways, no issues with HardHitter's installation.
 
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