Surviving the PG&E test?

[Boatguy]

I've been considering the the Tesla PVs and PW, but my experience with Tesla cars has made me very cautious. Tesla as a company over promises and under delivers. Tesla service frequently blames any problem on "software" as though Tesla had no control over the software.

In typical Tesla fashion the PVs and PW are promised to be a painless installation experience with efficient and reliable operation.

Various threads have referred to some real deal breakers:

- Neurio module failure bringing down the entire system with service personnel not available for 1-2 weeks.

- Over six months from order to install.

- PW output not compatible with LED lighting (my entire house has LED lighting)

PG&E has just had two monster shut downs which seems like a good test. I know most participants on this forum have already made their purchase which introduces a significant amount of "confirmation bias", but please give me your unvarnished experience.

1) Installation? Timely? Professional? Aesthetically acceptable?

2) Roof penetrations? Leaks. Stability over time in big wind, earthquakes, etc?

3) Actual output within the range that was expected when you made the commitment?

4) PW working reliably when PG&E shuts things down?

Thank you.

 

[patrick40363]

I have 2 powerwalls and they are working great. They re-charged off my solar panels today. Power has been off since 755pm Saturday. My panels were installed long ago.

 

[Zythryn]

PW output not compatible with LED lighting (my entire house has LED lighting)

Just wanted to throw in my experience here. I have never had any issues with our LED lights when the PWs were powering our house.
I can’t speak to the other issues.

 

[gpez]

- PW output not compatible with LED lighting (my entire house has LED lighting)

This misconception really needs to die.. The Powerwall output is perfectly compatible with LED lighting.

When paired with solar and with no grid connection the Powerwall signals to the inverters that it is full by increasing the AC frequency from the standard of 60hz in the US. Modern inverters will shut down starting as low as 60.5hz after a few minutes and instantly at 62hz. This behavior can be confirmed if your inverters are UL 1741 SA certified, the designation that the inverter was tested and properly shuts down in the time allotted at these frequencies. Tesla, however, has pre-configured Powerwalls to set the frequency to 66hz in this scenario which is clearly too high as at these high frequencies sensitive electronics can misbehave. The best guess here is that Tesla didn't want to risk a non 1741 certified inverter staying up when the batteries are full so the default is something much higher.

The fix is simply to call Tesla to tell them you have a 1741 certified inverter and have them remotely update your Powerwall configuration to a maximum 62.5hz. This took me all of 3 minutes to do on the phone with them.

Again this is ONLY when the grid is unavailable to dump excess solar power to, any other time the Powerwall will hum right along at 60hz and your LED lights will be happy.

 

[MorrisonHiker]

We just did a multi-day off-grid test in Colorado. Our Powerwalls and solar worked great to keep everything running perfectly. Our Powerwalls usually charged up to 85% each day and got down to as low as 14% one day. The Powerwalls would start raising the frequency when they were near 85% and the inverters would instantly shut off so we never had an issue with UPS devices, LEDs or induction range during this test.

Last March, we did have an issue where the Powerwalls were putting out too high of a frequency when they got down to 5% during a 45 hour outage. Others, such as @bmah did mention that if the Powerwalls are too fully charged they can temporarily put out a high frequency. He had a good suggestion where you could just charge the car for a bit in order to drain the batteries to get them back down to below 95% and then the frequency would return to normal. Others have said that you can contact Tesla and they can adjust the maximum frequency output by the Powerwalls so they they don't go above 62 Hz (or so) and avoid any problems.

 

[Xminus6]

I have a question: when you put a deposit down are they just putting you in contact with a contracted installer? I have an existing relationship with the company that’ installed my solar panels. Would I get faster service through Tesla’s website or likely through my solar provider?

 

[GenSao]

I have a question: when you put a deposit down are they just putting you in contact with a contracted installer? I have an existing relationship with the company that’ installed my solar panels. Would I get faster service through Tesla’s website or likely through my solar provider?

Tesla will use their own staff when you contact them directly to install solar panels and/or Powerwall(s). You can concurrently contact your solar provider to see if they separately install Powerwalls. Do note, their cost will likely be higher.

Regarding who is faster, it depends on their respective order backlog and schedule. You may find the 3rd party installer may be faster.

 

[ajdelange]

I have a question: when you put a deposit down are they just putting you in contact with a contracted installer? I have an existing relationship with the company that’ installed my solar panels. Would I get faster service through Tesla’s website or likely through my solar provider?

The word in the industry is that Tesla will not be doing installations any more. Got that from my solar provider (a Tesla dealer). Take that for what it's worth. If it's true you'll get a quicker install from a solar installation outfit that is an authorized Power Wall dealer than you will from Tesla. And from what I see here that may be the case even if it isn't.

 

[barely]

This misconception really needs to die.. The Powerwall output is perfectly compatible with LED lighting.

When paired with solar and with no grid connection the Powerwall signals to the inverters that it is full by increasing the AC frequency from the standard of 60hz in the US. Modern inverters will shut down starting as low as 60.5hz after a few minutes and instantly at 62hz. This behavior can be confirmed if your inverters are UL 1741 SA certified, the designation that the inverter was tested and properly shuts down in the time allotted at these frequencies. Tesla, however, has pre-configured Powerwalls to set the frequency to 66hz in this scenario which is clearly too high as at these high frequencies sensitive electronics can misbehave. The best guess here is that Tesla didn't want to risk a non 1741 certified inverter staying up when the batteries are full so the default is something much higher.

The fix is simply to call Tesla to tell them you have a 1741 certified inverter and have them remotely update your Powerwall configuration to a maximum 62.5hz. This took me all of 3 minutes to do on the phone with them.

Again this is ONLY when the grid is unavailable to dump excess solar power to, any other time the Powerwall will hum right along at 60hz and your LED lights will be happy.

I too am in the middle of the PG&E fun. I worked with Tesla after the first PG&E outage and before the second one, to get them to fix the frequency issue. Here is a snippet of the graph when the power went off during this latest outage:

My entire house is filled, except for a couple of stragglers, with LED bulbs. I have not seen a single issue with them during this outage.

What I did discover is that I might have undersized our system for October/November power events.

We installed an 8.2kW solar + 2 PowerWalls system. The outage started at 9:44 pm on 10/26, so we didn't have to start draining down the battery until then. By morning, after accounting for the morning "get ready for work usage", the SOC was 62%. The battery didn't start charging until 9:20 am due to some hills and trees blocking the early morning sun. The battery charged to 92.6% by 12:30 pm. At that point, it started throttling the solar (maybe cooling?). The solar was out for ~ 5.5 minutes, then came back for ~8 minutes and cycled back and forth keeping the SOC at 94-95% I think the PW's algorithm, needs a minor tweak. It should look at the time of day and the normal solar production. It should bring the PW up closer to 100% SOC at the end of the charging day when off-grid. That 5% is almost 2 hours of overnight runtime.

Today, the SOC got down to 38.5% before solar production exceeded usage. I'll see how long it takes for the battery to get back up to a "full" SOC.

 

[Xminus6]

Thanks. I’ve placed an order through Tesla’s website and still have an appointment with my provider.

Are the PW capable of rate arbitrage now? Last time I seriously considered them you couldn’t schedule their charge/discharge cycles to minimize daytime solar consumption. Without that they wouldn’t pay themselves off in any reasonable time scale.

 

[d21mike]

Thanks. I’ve placed an order through Tesla’s website and still have an appointment with my provider.

Are the PW capable of rate arbitrage now? Last time I seriously considered them you couldn’t schedule their charge/discharge cycles to minimize daytime solar consumption. Without that they wouldn’t pay themselves off in any reasonable time scale.

Only in Storm Watch Mode. So in normal mode no. I do not think PG&E would have sent Storm Watch Alert which I think would be nice since it is a definite loss of power?

Additional Powerwall Modes | Tesla

I heard the reason is because you are getting a SOLAR DISCOUNT. I am doing my system test today (install last week on Monday). But in your case where you should be paying full price for power walls maybe there is an exception?

 

[Xminus6]

Only in Storm Watch Mode. So in normal mode no. I do not think PG&E would have sent Storm Watch Alert which I think would be nice since it is a definite loss of power?

Additional Powerwall Modes | Tesla

I heard the reason is because you are getting a SOLAR DISCOUNT. I am doing my system test today (install last week on Monday). But in your case where you should be paying full price for power walls maybe there is an exception?

So the only way to use them is to charge them via solar and consume that during dark hours? Hmm.

Seems like it would actually cost you money then since you’re consuming Peak energy that could have been sold back but you’re using that energy during non-peak hours.

@bmah is that how it works for you (since you’re closest to my address)?

 

[MorrisonHiker]

So the only way to use them is to charge them via solar and consume that during dark hours? Hmm.

Seems like it would actually cost you money then since you’re consuming Peak energy that could have been sold back but you’re using that energy during non-peak hours.

We charge ours via solar early in the day. Then everything else is exported to the grid during part-peak and peak periods. Virtually all household usage (taken from the grid) is at off-peak rates because the Powerwalls power the house through all of peak and nearly all of part-peak. The credits I earn during peak and part-peak give more "bang for the buck" as they are earned at the same rate that I would pay but only deducted out at the off-peak rate. Fortunately, where we live, the credits can rollover forever and don't expire.

If it's peak period and they aren't fully charged, it will stop charging them and try to export as much as possible.

Powerwalls can charge from the grid when Storm Watch is enabled (by the owner) and activated (by Tesla).

 

[d21mike]

So the only way to use them is to charge them via solar and consume that during dark hours? Hmm.

Seems like it would actually cost you money then since you’re consuming Peak energy that could have been sold back but you’re using that energy during non-peak hours.

@bmah is that how it works for you (since you’re closest to my address)?

I am SCE on a grandfathered plan where my PEAK is 2-8pm and my super off peak is 10pm-8am where I was charging my cars (MS and M3). Not sure exactly what I will do going forward. I am grandfathered unit 2022 where my PEAK will be 4-9.

Excess is after fully charging my battery goes to the GRID and I get CREDIT from the TIME I sent it. So from 2-4 is where I will get the most for my solar. I can then use those credits back at my super low rate so I get like 4x usage for charging my cars if that is what I plan to do.
After 1 year I can sell back excess credits for .03 wholesale so maybe better to use them but again not sure.

BTW... The guy just left after doing a FULL SYSTEM TEST. And he said just leave it on for now for testing.

 

[Xminus6]

I am SCE on a grandfathered plan where my PEAK is 2-8pm and my super off peak is 10pm-8am where I was charging my cars (MS and M3). Not sure exactly what I will do going forward. I am grandfathered unit 2022 where my PEAK will be 4-9.

Excess is after fully charging my battery goes to the GRID and I get CREDIT from the TIME I sent it. So from 2-4 is where I will get the most for my solar. I can then use those credits back at my super low rate so I get like 4x usage for charging my cars if that is what I plan to do.
After 1 year I can sell back excess credits for .03 wholesale so maybe better to use them but again not sure.

BTW... The guy just left after doing a FULL SYSTEM TEST. And he said just leave it on for now for testing.

Sounds like you’re on EV-A like I am. The main concern I see is that you’re still consuming your own solar generation to charge your PW rather than selling it.

Obviously if your PWs are fully charged the extra gets sold back. But when you do that aren’t you consuming/storing your solar energy, worth ~$.40 to use it during Partial Peak and Off Peak times are night when Grid energy is $.11?

I can’t figure out the economics of it without rate arbitrage. If it doesn’t pay off, then that’s okay too because it acts as a backup for your home but the purchasing decision is affected by whether or not there’s a reasonable payback period.

We’re never net negative at True Up anyway so I’m not that concerned about net annual excess generation.

 

[gpez]

I too am in the middle of the PG&E fun. I worked with Tesla after the first PG&E outage and before the second one, to get them to fix the frequency issue. Here is a snippet of the graph when the power went off during this latest outage:

View attachment 470788

My entire house is filled, except for a couple of stragglers, with LED bulbs. I have not seen a single issue with them during this outage.

What I did discover is that I might have undersized our system for October/November power events.

We installed an 8.2kW solar + 2 PowerWalls system. The outage started at 9:44 pm on 10/26, so we didn't have to start draining down the battery until then. By morning, after accounting for the morning "get ready for work usage", the SOC was 62%. The battery didn't start charging until 9:20 am due to some hills and trees blocking the early morning sun. The battery charged to 92.6% by 12:30 pm. At that point, it started throttling the solar (maybe cooling?). The solar was out for ~ 5.5 minutes, then came back for ~8 minutes and cycled back and forth keeping the SOC at 94-95% I think the PW's algorithm, needs a minor tweak. It should look at the time of day and the normal solar production. It should bring the PW up closer to 100% SOC at the end of the charging day when off-grid. That 5% is almost 2 hours of overnight runtime.

Today, the SOC got down to 38.5% before solar production exceeded usage. I'll see how long it takes for the battery to get back up to a "full" SOC.

@barely if your inverters support it look to have them configured for production ramp down at high frequencies. For my Enphase inverters I've applied the grid profile that enables this and effectively ramps down the solar production after the frequency rises past 60.20 Hz. This prevents the "flip flop" effect you're seeing at high SOCs during the day when solar is being produced.

Start frequency 60.20 Hz
Start delay 0.0 ms
Ramp down rate 83.00 %/Hz

 

[d21mike]

Sounds like you’re on EV-A like I am. The main concern I see is that you’re still consuming your own solar generation to charge your PW rather than selling it.

Obviously if your PWs are fully charged the extra gets sold back. But when you do that aren’t you consuming/storing your solar energy, worth ~$.40 to use it during Partial Peak and Off Peak times are night when Grid energy is $.11?

I can’t figure out the economics of it without rate arbitrage. If it doesn’t pay off, then that’s okay too because it acts as a backup for your home but the purchasing decision is affected by whether or not there’s a reasonable payback period.

We’re never net negative at True Up anyway so I’m not that concerned about net annual excess generation.

I am with SCE: TOU-D-B

My main reason for the Power Walls is prevent power outage. The cost of my 2 power walls is $14,100 + installation which was discounted (I think because I got both Solar and Power walls). Also, I get 30% discount on the $14,100 so the cost of them is $9,870. A friend of mine got a Generator installed and the cost was around $12k (no tax credit). So, I am really only concerned with ROI on the Solar and I feel good about that.

Since I just got it turned on today I am not sure how I will fully utilized everything. I also have 2 Tesla's. Model S and 3. I also installed 2 Wall Chargers on a single 60 amp Load Sharing Circuit.

My original plan was to use the Power walls during Peak time only (2pm - 8pm). But I should be getting solar between 2-4 so maybe 4-8. When we turned on the system about 11:30am I was getting about close to 9kw. I have a 12kw system with 7.6 and 3.8 (11.4) inverters. It is now 1:45pm and my solar generation is about is 6.5kw. My power walls (2) are now at 64%. They were at 8% when we started. We did turn off the power to the grid to test around 11:45am and also started charging both cars for about 10 minutes. My AC is on now and it pulls about 3kw and with it off I am pulling about 1.2kw.

Rates for TOU-D-B:

Highest Rates: Weekdays 2-8 p.m.

Daily Basic Charge: $0.50 per day
Minimum Daily Charge: None
Baseline Credit: None

Summer Rates
Summer rates apply June through September. Rates are per kWh.

Weekday Summer Rates
Off-Peak: 16 cents from 8 a.m. to 2 p.m., and 8 p.m. to 10 p.m.
Super Off-Peak: 10 cents from 10 p.m. to 8 a.m.
On-Peak: 48 cents from 2 p.m. to 8 p.m.

Weekend Summer Rates
Off-Peak: 16 cents from 8 a.m. to 10 p.m.
Super Off-Peak: 10 cents from 10 p.m. to 8 a.m.

Winter Rates
Winter rates apply October through May. Rates are per kWh.

Weekday Winter Rates
Off-Peak: 15 cents from 8 a.m. to 2 p.m., and 8 p.m. to 10 p.m.
Super Off-Peak: 11 cents from 10 p.m. to 8 a.m.
On-Peak: 24 cents from 2 p.m. to 8 p.m.

Weekend Winter Rates
Weekend Off-Peak: 15 cents from 8 a.m. to 10 p.m.
Super Off-Peak: 11 cents from 10 p.m. to 8 a.m.

 

[miimura]

So the only way to use them is to charge them via solar and consume that during dark hours? Hmm.

Seems like it would actually cost you money then since you’re consuming Peak energy that could have been sold back but you’re using that energy during non-peak hours.

@bmah is that how it works for you (since you’re closest to my address)?

I calculate that my usage pattern will earn me more than $700 per year in arbitrage with the PG&E EV-A rate. EV2-A arbitrage is similar even though your surplus solar will earn you less. If you use more Peak energy in Summer than me and/or have more generation in Winter than me, you could save dramatically more than me.

This is a typical day for me with Time Based Control. The Powerwalls charge from solar in the morning, then power the house and let all the solar earn Peak NEM credits. Overnight car charging is completely from Off-Peak grid power.

 

[Boatguy]

How close was Tesla's pre-purchase estimate of your PV output compare with the estimate after you agreed to a purchase and then compared with your actual experience?

 

[Patrick66]

What I did discover is that I might have undersized our system for October/November power events.

I imagine more and more people are going to start realizing that; you need to start oversizing the PV to actually be off grid in the fall/winter. I think solutions that allow for using a portable generator to charge the battery are going to be needed to keep Tesla in the game. For a once-in-a-year event, running a portable 2kW generator for 8 hours might be a better solution than trying to grossly oversize everything.