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Surviving the PG&E test?

@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

Thanks @gpez. It's a SolarEdge SE7600H. I'll start looking through the manual and see what I can find.
 

gpez

Member
Apr 25, 2019
794
662
USA
Try "Power Frequency" in the "Active Power Configuration"

"P(f) – Power Frequency: This is used when frequency-based power reduction is required. This defines a linear graph set by two points. The inverter de-rates power according to the defined graph, until the frequency reaches the trip value and the inverter disconnects (the trip point is preset per country therefore does not need to be defined as one of the two points)."
 
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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.

View attachment 470864
So PW cannot be charged at night from Grid power to be consumed during Peak period?

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.
Thanks for taking the time to break it down and write it out. So PW doesn't seem like it will do the optimal thing, which is to charge off of Grid and then sell back as much solar generation as possible. The idea of charging during Partial Peak (or Off-Peak as SCE calls it) and then consuming during Peak obviously gives less arbitrage but I supposed it's the second best option.

We have a 14.1kWh system but since I'm home during the day our consumption during solar production hours is greater than it was when I was in an office. So I'm burning some of that ideal solar generating time. They're all sort of screwing us by shifting the Peak hours anyway so I suppose we just have to maximize what we can at any given point.
 
So PW cannot be charged at night from Grid power to be consumed during Peak period?


Thanks for taking the time to break it down and write it out. So PW doesn't seem like it will do the optimal thing, which is to charge off of Grid and then sell back as much solar generation as possible. The idea of charging during Partial Peak (or Off-Peak as SCE calls it) and then consuming during Peak obviously gives less arbitrage but I supposed it's the second best option.

We have a 14.1kWh system but since I'm home during the day our consumption during solar production hours is greater than it was when I was in an office. So I'm burning some of that ideal solar generating time. They're all sort of screwing us by shifting the Peak hours anyway so I suppose we just have to maximize what we can at any given point.
Right you are on the shifting of Peak to further in the day. I work from home as well and my wife is retiring so not going to be creating a lot of credits either. Hoping to make enough extra to fill the batteries and a little extra to charge the cars. Working from home I do not use a lot of energy in the car. Two sides to working at home.
 
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miimura

Well-Known Member
Aug 21, 2013
7,441
7,454
Los Altos, CA
So PW cannot be charged at night from Grid power to be consumed during Peak period?
If you are in the USA and have solar, you cannot charge from the grid except during Storm Watch events. This is an artifact of the 30% Federal Investment Tax Credit that is available on solar charged energy storage systems. If you get a Powerwall without solar or you live in the UK or Australia, it will charge from the grid if it thinks it is necessary to power through the Peak period.
 
If you are in the USA and have solar, you cannot charge from the grid except during Storm Watch events. This is an artifact of the 30% Federal Investment Tax Credit that is available on solar charged energy storage systems. If you get a Powerwall without solar or you live in the UK or Australia, it will charge from the grid if it thinks it is necessary to power through the Peak period.
I see. Thanks. Are the Federal credits still in play? So you can really only arbitrage between your early Partial Peak generation and your Peak consumption it seems. That’s rather counter to my system which was designed to maximize afternoon sun to offset peak hours.
 

miimura

Well-Known Member
Aug 21, 2013
7,441
7,454
Los Altos, CA
I see. Thanks. Are the Federal credits still in play? So you can really only arbitrage between your early Partial Peak generation and your Peak consumption it seems. That’s rather counter to my system which was designed to maximize afternoon sun to offset peak hours.
Yes, Federal Credit is 30% through 12/31/19 and is 26% in 2020. I don't recall the next step after that.

Today, on EV-A that is true. It is arbitrage between Part-Peak and Peak. However, PG&E is pushing people into EV2-A which runs Off-Peak from Midnight to 3pm. So, then you will have arbitrage from Off-Peak to Part-Peak and Peak. The problem is that when your batteries are filled at noon, you only get Off-Peak NEM credits from noon-3pm. Any generation you have during Peak will still earn you max credits because your house will be powered from battery. My solar system is so small that I am production limited on my arbitrage about 5 months a year.
 
One other comment: the Investment Tax Credit (ITC) has a five year vesting period. The hope is that Tesla will eventually allow grid charging for customers who are fully vested. It would take a lot of rate arbitrage to earn back the 30% credit in five years, so I think for most people it's still more advantageous to get the credit.
 

KSilver2000

Active Member
Dec 23, 2017
1,368
2,438
CA
The hope is that Tesla will eventually allow grid charging for customers who are fully vested. It would take a lot of rate arbitrage to earn back the 30% credit in five years, so I think for most people it's still more advantageous to get the credit.

I don't think the capability of grid charging rests on Tesla. It likely has to do with some kind of regulation. On the Tesla side, it's just software. If they really wanted to allow grid charging, they could have done so long time ago.

But, yes, as you mention, PWs are not meant to be profitable for the consumer through rate arbitrage as it stands. From our usage calculation, it pencils out to be about 10 years pay back period without incentives. In less than half that time, I expect much cheaper and larger Tesla Powerwalls (v3, v4?).

I'll probably invest in a PW once the payback period gets closer to being equivalent to the payback of PV. Whether that's from grid charging being allowed or cheaper PW.
 
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I don't think the capability of grid charging rests on Tesla. It likely has to do with some kind of regulation. On the Tesla side, it's just software. If they really wanted to allow grid charging, they could have done so long time ago.
Yes, my point is that the "regulation" that is causing them to do this is just the ITC (they mention it on their web site). Given that Powerwalls installed without solar do grid charge already shows that it's definitely allowed under certain circumstances. I suspect that exporting from the Powerwalls to the grid would be more of an issue, but just discharging to satisfy the house load as they do today would not be covered by any other regulation or contract.
 

MorrisonHiker

Well-Known Member
Moderator
Mar 8, 2015
10,772
11,090
Colorado
I have solar and power walls at my home in SOCAL. If I have a Power Failure my house is fully backed up. But not sure I would still have internet. It would depend on if my ISP is fully backed up, right?

Those in PG&E with the power outages, if you have power backup will you still have internet? If so, who is your ISP?
When we've had power outages in Colorado, our internet has still been fine most of the time. If it goes down, I just set up a wifi hotspot on my phone and use that for internet. I've done that in the past and still been able to work from home during a 45 hour power outage. :cool:
 
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I have solar and power walls at my home in SOCAL. If I have a Power Failure my house is fully backed up. But not sure I would still have internet. It would depend on if my ISP is fully backed up, right?

Those in PG&E with the power outages, if you have power backup will you still have internet? If so, who is your ISP?
Comcast/Xfinity has backup only for a few hours at best, so we lost internet each time PG&E blacked us out.
The Powerwall/Solar made sure we had electricity the whole time.
We switched to a MiFi = cell based internet, but that works only as a minimal setup for a whole house due to the speed we can get in our location and limitations of the device itself (number of clients<=14).
 
I have solar and power walls at my home in SOCAL. If I have a Power Failure my house is fully backed up. But not sure I would still have internet. It would depend on if my ISP is fully backed up, right?

Those in PG&E with the power outages, if you have power backup will you still have internet? If so, who is your ISP?
For those of us in California that are being intentionally blacked out by the utilities the issue is that the blackout is so widespread that the ISPs are going down as well. If you’re experienced a local accidental blackout it presumably wouldn’t affect your ISPs switching station unless you live near it.
 
For those of us in California that are being intentionally blacked out by the utilities the issue is that the blackout is so widespread that the ISPs are going down as well. If you’re experienced a local accidental blackout it presumably wouldn’t affect your ISPs switching station unless you live near it.
Exactly. There are also plenty of news stories about intentionally blacked out areas losing both wired internet and cellular services. As both rely on PG&E and have limited backup batteries/generators.
 

astrorob

stealth performance M3
Aug 27, 2014
602
157
oakland, ca
I have solar and power walls at my home in SOCAL. If I have a Power Failure my house is fully backed up. But not sure I would still have internet. It would depend on if my ISP is fully backed up, right?

Those in PG&E with the power outages, if you have power backup will you still have internet? If so, who is your ISP?

i can tell you my experience -

the moment the power went down comcast's headend went down as well - i have UPS on my network infrastructure inside the house and my cablemodem was still powered. something very bad happened in my immediate area with respect to comcast's network - there were nearby neighborhoods which were not part of the PSPS who also lost their comcast internet. in addition, it took comcast > 36h to restore service to my house past the point where power returned. so there may have been some damage to their equipment caused by the shutoff. i know in prior non-planned outages my modem was able to keep sync with the headend.

my backup internet - an ancient DSL line terminated in the nearest central office (~2mi away) - stayed up throughout the shutoff. but the CO is so far away that they may have never lost power and so their power backup may not have been tested.

cellular data continued to work throughout but i suspect my phone can see some cell towers which still had power. we were on the western edge of the shutdown zone which broadly ran north-south thru the east bay hills. i heard that in marin since the PSPS was so widespread that the battery backups on the cell towers started to fail and people were truly in the dark.
 
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.
Same here. My panels were installed 2016 and PowerWalls 2017. No PG&E for almost 2 days, and never lost power. Almost half a thousand days continuous since my last tests that shut it down.

Some weak devices require reboot, and most solid devices don’t.

The only weak link was the one utility that didn’t back up their junk. Comcast had a battery backup on the poles that lasted only a few hours. Everything else stayed on. Each utility that had backups (water, AT&T) stayed on. Our water district had to station generators only a week earlier to make this happen, and AT&T had to bring generators to a few locations.
 
i can tell you my experience -

the moment the power went down comcast's headend went down as well - i have UPS on my network infrastructure inside the house and my cablemodem was still powered. something very bad happened in my immediate area with respect to comcast's network - there were nearby neighborhoods which were not part of the PSPS who also lost their comcast internet. in addition, it took comcast > 36h to restore service to my house past the point where power returned. so there may have been some damage to their equipment caused by the shutoff. i know in prior non-planned outages my modem was able to keep sync with the headend.

my backup internet - an ancient DSL line terminated in the nearest central office (~2mi away) - stayed up throughout the shutoff. but the CO is so far away that they may have never lost power and so their power backup may not have been tested.

cellular data continued to work throughout but i suspect my phone can see some cell towers which still had power. we were on the western edge of the shutdown zone which broadly ran north-south thru the east bay hills. i heard that in marin since the PSPS was so widespread that the battery backups on the cell towers started to fail and people were truly in the dark.

What probably happened is the Node got taken offline by the power outage. In order for you to maintain service the Node has to have some type of backup power. Usually these Nodes will have some type of battery backup for limited VOIP service while the power is offline. This is supposed to give enough time for a technician to be dispatched with a Generator that they can then plug-in to restore full service to the Node. What I suspect happened is that Comcast just got overwhelmed with the number of Nodes down because of these wide spread power outages and made a decision not to sent out tech's with a Generator. My Dad lives in San Diego and SDG&E recently cut his power and he lost his Cox cable service but within a couple of hours a tech rolled out and hooked up a Generator to the Node and service was fully restored. However SDG&E is cutting power to much less customers than PG&E so it is easier for Cox to keep up with the power disruptions.

Usually from the Node you there is fiber back to a hub-site that serves a larger area. These hub-sites are larger hardened facilities with UPS plus dual generators and at least a weeks worth of fuel on-site. However I know these wide spread power outages are really straining the telecommunications equipment to keep equipment online through these extended outages that are happening one after another.
 

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