PSPS setting for powerwall

[Merrill]

Just wondering for those who run their house during the peak time on the powerwall when a PSPS is eminent do you change your powerwall setting to backup so the battery is at 100% before the power is shut off. Right now I end up with around 65% left in the morning, if PG&E shuts the power off around 8am for 12 plus hours I would not have enough in the powerwall to get thru that power shut off.

 

[marx1]

In California, the PSPS are treated as a stormwatch event, just like Red Flags. As soon as they are announced my power walls kick into stormwatch during the warning window. I've had it trigger early and say "Charging powerwalls for upcoming stormwatch" and force a grid-charge.

 

[Merrill]

In California, the PSPS are treated as a stormwatch event, just like Red Flags. As soon as they are announced my power walls kick into stormwatch during the warning window. I've had it trigger early and say "Charging powerwalls for upcoming stormwatch" and force a grid-charge.

So I need to activate storm watch.

 

[Merrill]

I have another question, if the PSPS is going to shut our power off tomorrow at 8am can I let my Powerwalls go thru the time based setting from 4pm to 9pm and then after that is done turn on storm watch to charge the Powerwalls from the grid at off peak.

 

[bmah]

I have another question, if the PSPS is going to shut our power off tomorrow at 8am can I let my Powerwalls go thru the time based setting from 4pm to 9pm and then after that is done turn on storm watch to charge the Powerwalls from the grid at off peak.

Hi @Merrill!

Short answer: Yes.

Longer answer: I will usually leave my system in its normal mode of operation (with Storm Watch disabled) until I know the scheduled start time of the PSPS. I'll enable Storm Watch during the last off-peak period before that time and let the batteries fill up from the grid during off-peak. I'll usually also increase my reserve percentage "just in case" Storm Watch doesn't kick in for some reason. Storm Watch would stay enabled until power has been restored and there are no more PSPS events scheduled in the near future.

There are probably some edge cases this procedure doesn't cover. Also you can tweak this procedure to not draw so much from the grid, or to leave some headroom in the batteries to absorb your day-of-the-PSPS solar production. But that's the basic idea.

Bruce.

 

[Merrill]

Hi @Merrill!

Short answer: Yes.

Longer answer: I will usually leave my system in its normal mode of operation (with Storm Watch disabled) until I know the scheduled start time of the PSPS. I'll enable Storm Watch during the last off-peak period before that time and let the batteries fill up from the grid during off-peak. I'll usually also increase my reserve percentage "just in case" Storm Watch doesn't kick in for some reason. Storm Watch would stay enabled until power has been restored and there are no more PSPS events scheduled in the near future.

There are probably some edge cases this procedure doesn't cover. Also you can tweak this procedure to not draw so much from the grid, or to leave some headroom in the batteries to absorb your day-of-the-PSPS solar production. But that's the basic idea.

Bruce.

Thanks Bruce I appreciate your help, have not used the system during a PSPS since installed so just trying to decide what to do. I think I will let the system stay as is until after 9pm and by then should know if they are actually going to do the PSPS. What do you set your reserve for in this situation.

 

[h2ofun]

Hi @Merrill!

Short answer: Yes.

Longer answer: I will usually leave my system in its normal mode of operation (with Storm Watch disabled) until I know the scheduled start time of the PSPS. I'll enable Storm Watch during the last off-peak period before that time and let the batteries fill up from the grid during off-peak. I'll usually also increase my reserve percentage "just in case" Storm Watch doesn't kick in for some reason. Storm Watch would stay enabled until power has been restored and there are no more PSPS events scheduled in the near future.

There are probably some edge cases this procedure doesn't cover. Also you can tweak this procedure to not draw so much from the grid, or to leave some headroom in the batteries to absorb your day-of-the-PSPS solar production. But that's the basic idea.

Bruce.

I just leave SW off. If I ever get a PSPS, I will just adjust my house used based on solar production. In worst case, since I have batteries on 2 separate GW's, I can could always run an extension cord from one set if needed. Or just turn on my generator.

 

[bmah]

I just leave SW off. If I ever get a PSPS, I will just adjust my house used based on solar production. In worst case, since I have batteries on 2 separate GW's, I can could always run an extension cord from one set if needed. Or just turn on my generator.

That works for you, Mister “30 kW Solar System”.

Bruce.

 

[getakey]

Unless you have been through one annual true up with PWs, I wouldn't play games with the SW feature to save a few bucks. Especially with the new Fast Trigger shut off from PG&E why risk not having enough PW capacity for n unplanned shut off?

 

[jjrandorin]

Unless you have been through one annual true up with PWs, I wouldn't play games with the SW feature to save a few bucks. Especially with the new Fast Trigger shut off from PG&E why risk not having enough PW capacity for n unplanned shut off?

This all comes down to an individuals risk tolerance, though right? Some people may not want to pull "peak priced power" to fill their powerwalls, even in the face of a possible PSPS. Others may not care and want to ensure their powerwalls are full.

I personally fall into the second camp. I leave stormwatch mode on, and if it activates and starts filling my powerwalls I dont care. In my specific case, however, because I am still on a tiered rate (not TOU), I dont currently have such a thing as "peak TOU power".

Once my powerwalls fill (either from solar or in stormwatch mode) and all solar goes back out to the grid, it all works out the same for me. If / when I get moved to a TOU rate, I likely would do something like @bmah said in post #5, but like I mentioned, this all boils down to risk tolerance on powerwalls being full for a PSPS vs possibly charging during "peak TOU" time.

 

[getakey]

This all comes down to an individuals risk tolerance, though right? Some people may not want to pull "peak priced power" to fill their powerwalls, even in the face of a possible PSPS. Others may not care and want to ensure their powerwalls are full.

I personally fall into the second camp. I leave stormwatch mode on, and if it activates and starts filling my powerwalls I dont care. In my specific case, however, because I am still on a tiered rate (not TOU), I dont currently have such a thing as "peak TOU power".

Once my powerwalls fill (either from solar or in stormwatch mode) and all solar goes back out to the grid, it all works out the same for me. If / when I get moved to a TOU rate, I likely would do something like @bmah said in post #5, but like I mentioned, this all boils down to risk tolerance on powerwalls being full for a PSPS vs possibly charging during "peak TOU" time.

I agree. Having been through an extended PSPS w/o PW, my risk tolerance is very low. Further, in my first year of PW, I put reserve fairly low (33%) using Cost Saving, but increased it if storm was forecasted. I ended up going negative on my true up by a substantial amount. Now I know, I have a lot of capacity to play with and its not worth it to scratch every savings I can (as it won't end up being a savings at all).

edit: forgot to add link to "fast trip"

PG&E's new "fast trip" feature a cause of more frequent and longer power outages

In a late Friday afternoon email to customers, PG&E provided an explanation for the increased power outages occurring in the foothills these past few weeks. A new feature called “fast trip” is designed to “quickly and automatically turn off power if an object strikes a line or there is an issue...

yubanet.com

 

[bmah]

I agree. Having been through an extended PSPS w/o PW, my risk tolerance is very low. Further, in my first year of PW, I put reserve fairly low (33%) using Cost Saving, but increased it if storm was forecasted. I ended up going negative on my true up by a substantial amount. Now I know, I have a lot of capacity to play with and its not worth it to scratch every savings I can (as it won't end up being a savings at all).

Since I was invoked up-thread ( ), I'll weigh in with a few more thoughts. Sorry if I'm straying a bit from the original topic, but one could consider this as background/explanation of why I do what I do.

Basically everyone's situation is going to be different. Not just risk tolerance, but how reliable your grid normally is, how much solar and how much battery you have in relation to your house's normal needs, how much load you are willing to shed during outages, what your goals are as far as energy devices like solar and batteries, etc.

My Powerwalls were purchased as a cost-savings measure. Originally I wanted more solar capacity (our solar system was sized back in 2010 to cover about 2/3 of our usage, and that was before we got two plug-in vehicles). After a discussion with Tesla's second-system group, we concluded that Powerwalls made more sense for me. Back-up was a secondary consideration, and at that time, the longest we'd ever been without power was around 9 hours. Our Powerwalls were installed and on-line about 6 months before the NorCal-wide PSPS events of 2019.

For us (probably for most people) the worst-case scenario would an unplanned grid outage that comes at night, batteries down to the reserve setting, and we need to run the house on what's left until we start getting solar production the next day. Our reserve percentage (currently 30% for this time of the year but I raise it as the days get shorter and there's less solar production) is enough to cover most (probably not all) variations of that scenario. The only time anything like that has happened in 12 years of living here was the aforementioned 9-hour outage, which actually happened before we had Powerwalls installed.

I'm pretty happy so far with the way this works...we've gone through multiple PSPS events (4 so far, if memory serves, longest was 60 hours) with no interruptions in the house power, as well as several planned and unplanned multi-hour outages (note that you don't get Stormwatch for planned maintenance activities, although those usually happen during the daytime).

Bruce.

 

[jjrandorin]

Since I was invoked up-thread ( )

(couldnt resist, lol...)