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Arizona Powerwall Installs

Dec 2, 2017
358
339
Arizona
I did a follow up question with my installer, and I agree I should use EER. But I still disagree with your statement. The reason high efficiency units drop out rapidly at higher temperatures (Arizona especially) is because the system cannot maintain an easy 1 deg F change. So it has to use the larger compressor or both compressors, which brings them back to EER 13'ish. (Likely along with my unit as well but nowhere "neer" as much EER.) If you want to compare specs, be my guest. I'm sure this has a gradient effect and may be just a curve function of 2nd stage compressor duty cycle.
All things being equal, I imagine if the best single stage A/C unit (~16 SEER) were pitted against the best variable speed unit (~26 SEER) and both were set to full blast all the time, they would roughly match efficiency. Variable speed units gain efficiency over single stage units because they don’t have to start/stop as much. Granted, in high temperatures there is more time spent “on” and less start/stop. But even in Arizona heat, A/C doesn’t run full blast all the time. They may take a hit, but variable speed units will still gain a lot of efficiency over single stage units in the heat and may even respond to sub-degree variations.

The XC20 units we have can run from 35-100% in 1% increments, and I haven’t seen them max out for long. In our hot Arizona September they used ~30% less power than the 13 SEER units we replaced.
 

SOULPEDL

Supporting Member
Jul 25, 2016
3,006
11,370
Arizona
All things being equal, I imagine if the best single stage A/C unit (~16 SEER) were pitted against the best variable speed unit (~26 SEER) and both were set to full blast all the time, they would roughly match efficiency. Variable speed units gain efficiency over single stage units because they don’t have to start/stop as much. Granted, in high temperatures there is more time spent “on” and less start/stop. But even in Arizona heat, A/C doesn’t run full blast all the time. They may take a hit, but variable speed units will still gain a lot of efficiency over single stage units in the heat and may even respond to sub-degree variations.

The XC20 units we have can run from 35-100% in 1% increments, and I haven’t seen them max out for long. In our hot Arizona September they used ~30% less power than the 13 SEER units we replaced.

Nice unit. Cost on a couple of those and 2 new heater units so it all matches, with install, would kill the bank. Maybe next time around, these are done, $5K everything, now able to backup whole home ;)

FYI, my AC can run solid for hours when it's baking here, but I could use more attic insulation. Adding 8kW PV panels on the west roof could help a bit there too from the shade.

20191007_133256.jpg
 
Dec 2, 2017
358
339
Arizona
Nice unit. Cost on a couple of those and 2 new heater units so it all matches, with install, would kill the bank. Maybe next time around, these are done, $5K everything, now able to backup whole home ;)

FYI, my AC can run solid for hours when it's baking here, but I could use more attic insulation. Adding 8kW PV panels on the west roof could help a bit there too from the shade.

View attachment 463735
Thanks - I didn’t mean to sound like I was bragging about our units. What you did at $5k is impressive and I have to hand it to you there and I’m glad it worked out. I was just using our units as a data point about effectiveness of high SEER units here in AZ. Far as I can tell the efficiency gain is still there at least in our case.
 
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SOULPEDL

Supporting Member
Jul 25, 2016
3,006
11,370
Arizona
After another SRP/Tesla meeting at my house, SRP finally approved use of my existing conduit (connecting panel to garage). I'm saving $2K and no ugly pipe at my entrance. I knew they'd understand the absurdity of digging another trench.

Install set for Tuesday! Tree is cut back, painting garage this weekend. Light grey wall, dark grey lettering, red logo and trim. Basically matching the PW colors. Dark grey maybe too dark for the whole wall and red is not my thing.
11-1-2019 9-38-04 AM.png


Logo colors.png
 

oldpueblo

Member
Apr 4, 2016
82
40
Gilbert
So I just docusigned the SRP interconnection agreement and my Tesla page says install coming soon, scheduling in 1-3 days. Anyone have any ideas roughly how long it was from that point till install day?
 

Chancellor32

Member
May 10, 2018
711
479
Queen Creek, AZ
So I just docusigned the SRP interconnection agreement and my Tesla page says install coming soon, scheduling in 1-3 days. Anyone have any ideas roughly how long it was from that point till install day?
Tesla has been working about 2-3 weeks out for installs. I would imagine you get scheduled around mid to end of Nov.
 

SOULPEDL

Supporting Member
Jul 25, 2016
3,006
11,370
Arizona
So I just docusigned the SRP interconnection agreement and my Tesla page says install coming soon, scheduling in 1-3 days. Anyone have any ideas roughly how long it was from that point till install day?

My SRP interconnect was sent to SRP approval Oct 29th, then sales sent me this letter Oct 30.

Updated documentation was sent to SRP yesterday for design approval. I saw the application approval come across yesterday – ETA is approximately 2 weeks.

On Thurs Oct 31st, I was given the OK to set an install date. My install is set for Nov 5th, so that should be a record. However, SRP was pulled in last month to solve a layout issue and I met everyone in person, twice. It was basically pre-approved.

I bought garage paint and NOT doing a red wall. I'm doing dark gray with white lettering (opposite powerwall colors). Red stripe in there somewhere. I'll post when done after install.
 
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SOULPEDL

Supporting Member
Jul 25, 2016
3,006
11,370
Arizona
Hey anyone have recommended App settings given the dual peak scenario in the Winter with SRP?

I picked up from another thread that they just set one huge peak spanning both. Remaining off-peak is the 6 hrs during EV charging 11Pm-5AM. Trying to only use grid at that time for pool pump, EV charging, and not use the batteries at all then to maximize savings. Seems a logical goal... anyone tried it?
 

SOULPEDL

Supporting Member
Jul 25, 2016
3,006
11,370
Arizona
Hey anyone have recommended App settings given the dual peak scenario in the Winter with SRP?

I picked up from another thread that they just set one huge peak spanning both. Remaining off-peak is the 6 hrs during EV charging 11Pm-5AM. Trying to only use grid at that time for pool pump, EV charging, and not use the batteries at all then to maximize savings. Seems a logical goal... anyone tried it?

Oh cool, it just switch to grid (11PM). Seems this works, so at 5AM, the batteries should kick back on and take me to sun o'clock. We'll see.
 
Dec 2, 2017
358
339
Arizona
Oh cool, it just switch to grid (11PM). Seems this works, so at 5AM, the batteries should kick back on and take me to sun o'clock. We'll see.
I do 5pm-9pm peak, 5am-5pm shoulder, 9pm-5am off peak. I figure this makes it so it will try not to use the battery during the morning peak, but try harder during the evening peak. Since there is usually plenty of solar in the middle of the day, the shoulder there doesn’t really seem to matter.
 

SOULPEDL

Supporting Member
Jul 25, 2016
3,006
11,370
Arizona
I do 5pm-9pm peak, 5am-5pm shoulder, 9pm-5am off peak. I figure this makes it so it will try not to use the battery during the morning peak, but try harder during the evening peak. Since there is usually plenty of solar in the middle of the day, the shoulder there doesn’t really seem to matter.
Interesting.... So, is it doing what you want it to do? Are you pulling anything from the grid in the morning peak time?
 
Dec 2, 2017
358
339
Arizona
Interesting.... So, is it doing what you want it to do? Are you pulling anything from the grid in the morning peak time?
It generally does what I want - typically not much from the grid in the morning peak and when I charge the Tesla at night it usually uses grid unless there is a surplus of battery. Having two “real” peak periods might be slightly better in some cases.
 

tmoz

S85D, Prius PiP
Aug 16, 2015
867
474
Gilbert, Arizona
How much are you guys saving off your normal electric bill.
For me with SRP, an 8 kW system would have costed $16 K after rebates, but only save me $500 per year. I don't use that much electricity to begin with, so maybe it's just me. SRP is not solar friendly. The Tesla people told me that the power packs weren't going to help save money as they were mainly for backup power. Their on-line calculator was not sophisticated enough to factor load shifting into the equation. Even their solar calculator had serious bugs - no wonder the unit is struggling. With $2/W installed, they should be doing a lot better.
 

dhskiracer71

Member
May 28, 2019
17
14
Fountain Hills, AZ
How much are you guys saving off your normal electric bill.
For me with SRP, an 8 kW system would have costed $16 K after rebates, but only save me $500 per year. I don't use that much electricity to begin with, so maybe it's just me. SRP is not solar friendly. The Tesla people told me that the power packs weren't going to help save money as they were mainly for backup power. Their on-line calculator was not sophisticated enough to factor load shifting into the equation. Even their solar calculator had serious bugs - no wonder the unit is struggling. With $2/W installed, they should be doing a lot better.

My summer bills peaked out at nearly $500 before and now under $150 due to solar, demand manager and PWs. Winter bills cut in half. Get a quote from a reputable local installer even if you go with Tesla for price. They will give you a good estimate of saving/ROI. I used Sun Valley Solar Systems and their calculations were actually VERY conservative. I’m doing much better than forecasted this year.
 

dhskiracer71

Member
May 28, 2019
17
14
Fountain Hills, AZ
My summer bills peaked out at nearly $500 before and now under $150 due to solar, demand manager and PWs. Winter bills cut in half. Get a quote from a reputable local installer even if you go with Tesla for price. They will give you a good estimate of saving/ROI. I used Sun Valley Solar Systems and their calculations were actually VERY conservative. I’m doing much better than forecasted this year.

Also, I’m in SRP, 8k system and had one PW but adding a second to fully squash peak usage and demand charges. I have 3 a/c units and pool with as large family always home so we use a good chunk of electricity. Solar plan rates are dirt cheap so it’s all about managing TOU and demand charges in the SRP territory.
 

dhskiracer71

Member
May 28, 2019
17
14
Fountain Hills, AZ
Hey anyone have recommended App settings given the dual peak scenario in the Winter with SRP?

I picked up from another thread that they just set one huge peak spanning both. Remaining off-peak is the 6 hrs during EV charging 11Pm-5AM. Trying to only use grid at that time for pool pump, EV charging, and not use the batteries at all then to maximize savings. Seems a logical goal... anyone tried it?

In the SRP you’ll do best with one large shoulder period covering both peak periods (no peak period setting). This is from many hours of studying the PW behavior and trial and error. Or better yet use Darwin’s SmartThings app to automate schedules.
 
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