What hours should I run my Powerwalls

[Merrill]

I would like to hear from anyone on how they use their Powerwalls. Currently I run the house of the Powerwalls during peak time (4pm to 9pm) but think I want to use less power from the grid. After the 4 to 9 usage I generally end up with 80 % left in the Powerwalls and it recharges back to 100% by 11 the next morning. The more I can cut down on the grid power the better.

 

[getakey]

What is your rate in the morning up until 4pm and rate after 9pm? If your rate at which you are charging PWs is the same rate as after 9pm, you would be losing 10% on the round trip. Lets say rate in morning is $.30/kWh. Then you are filling your PWs with power that is "worth" $.30/kWh. If the rate after 9pm is $.30/kWh, you would be avoiding $.30, but using PW electricity that costs $.33 due to 10% loss.

 

[h2ofun]

I would like to hear from anyone on how they use their Powerwalls. Currently I run the house of the Powerwalls during peak time (4pm to 9pm) but think I want to use less power from the grid. After the 4 to 9 usage I generally end up with 80 % left in the Powerwalls and it recharges back to 100% by 11 the next morning. The more I can cut down on the grid power the better.

I have mine set to balanced. Peak from 3pm to 1am. It still uses battery for most of the day. Charge back to 100% by noon. Off grid 99% of the time. So simple.

 

[Merrill]

I have mine set to balanced. Peak from 3pm to 1am. It still uses battery for most of the day. Charge back to 100% by noon. Off grid 99% of the time. So simple.

How does it use the battery most of the day, I assume it does not start charging until the sun is available.
Can you explain in more detail I’m new to this, thanks.

 

[MJ_CA_2019]

I also use Balanced with a reserve of 15%.
my peak time is 4-9 pm M-F

 

[h2ofun]

How does it use the battery most of the day, I assume it does not start charging until the sun is available.
Can you explain in more detail I’m new to this, thanks.

SInce this time of the year, my load on the batteries vs solar is such that I put the battery reserve at 10%. I set the peak from 3pm to 1am to make sure my batteries are used 100% during this time. It also means I am sending 100% of my solar back to PGE at the highest rates. But since the system learns, and sees I am not draining the batteries a lot, yet, no AC all day, yet, and lots of solar, the battery just keeps feeding house, When I look when I get up at like 4am, they are still like 70%.
Give it a try.

 

[SaveOurPlanet]

I think it depends on your goal, people talk about ROI and saving money but my only goal is to be off grid as much as I can, self reliant. I turned on my relatively small 6.5 kW solar roof + 2 PWs 2nd week of April and on self-powered, not a single kWh from PG&E so far except today. It is extremely foggy and did not see the sun all day at all, forecast says drizzle and cloudy the next few days so I switched it to backup only to use whatever little solar to charge the PWs. Usually my PWs get charged to 100% before noon time but today is like a stormy Winter day. I will switch it back to self-powered by 3:30.

 

[Merrill]

What is your rate in the morning up until 4pm and rate after 9pm? If your rate at which you are charging PWs is the same rate as after 9pm, you would be losing 10% on the round trip. Lets say rate in morning is $.30/kWh. Then you are filling your PWs with power that is "worth" $.30/kWh. If the rate after 9pm is $.30/kWh, you would be avoiding $.30, but using PW electricity that costs $.33 due to 10% loss.

My peak 4 to 9 is $.25 and all other time off peak $.22 this is winter thru May.

 

[h2ofun]

I think it depends on your goal, people talk about ROI and saving money but my only goal is to be off grid as much as I can, self reliant. I turned on my relatively small 6.5 kW solar roof + 2 PWs 2nd week of April and on self-powered, not a single kWh from PG&E so far except today. It is extremely foggy and did not see the sun all day at all, forecast says drizzle and cloudy the next few days so I switched it to backup only to use whatever little solar to charge the PWs. Usually my PWs get charged to 100% before noon time but today is like a stormy Winter day.

One also needs to know if they have to use the batteries, which I do by SGIP requirements

 

[Merrill]

I think it depends on your goal, people talk about ROI and saving money but my only goal is to be off grid as much as I can, self reliant. I turned on my relatively small 6.5 kW solar roof + 2 PWs 2nd week of April and on self-powered, not a single kWh from PG&E so far except today. It is extremely foggy and did not see the sun all day at all, forecast says drizzle and cloudy the next few days so I switched it to backup only to use whatever little solar to charge the PWs. Usually my PWs get charged to 100% before noon time but today is like a stormy Winter day. I will switch it back to self-powered by 3:30.

My goal is to use as little grid power as possible.

 

[Merrill]

I think it depends on your goal, people talk about ROI and saving money but my only goal is to be off grid as much as I can, self reliant. I turned on my relatively small 6.5 kW solar roof + 2 PWs 2nd week of April and on self-powered, not a single kWh from PG&E so far except today. It is extremely foggy and did not see the sun all day at all, forecast says drizzle and cloudy the next few days so I switched it to backup only to use whatever little solar to charge the PWs. Usually my PWs get charged to 100% before noon time but today is like a stormy Winter day. I will switch it back to self-powered by 3:30.

I have the same system 6.5 kW and 2 Powerwalls, so if I use self powered I will be off grid most of the time? I’m all electric and use around 1000 kW per month.

 

[h2ofun]

I have the same system 6.5 kW and 2 Powerwalls, so if I use self powered I will be off grid most of the time? I’m all electric and use around 1000 kW per month.

I need to maximize my generation credits with PGE for the winter since I have electric heat. If one has gas heat, its a totally different game.

 

[SaveOurPlanet]

I’ve been able to do so since I turned on my system and still manage to send some back to PG&E until today, that’s only because the weather outlook does not look good for the next few days. I’ve gone through 3 straight foggy days before and still not a single kWh from PG&E, but rain is a different story.

 

[h2ofun]

I’ve been able to do so since I turned on my system and still manage to send some back to PG&E until today, that’s only because the weather outlook does not look good for the next few days. I’ve gone through 3 straight foggy days before and still not a single kWh from PG&E, but rain is a different story.

Yes, when I get rain, and my production in the winter is only 5kwh for the solar in the day, but I use 50kwh for heating, I guess I will stuck pulling from PGE. This is why I need to get as much generation credits in the summer. BUT, if they throw out NEM2, I am screwed and spend a LOT of money for nothing!!

 

[getakey]

My peak 4 to 9 is $.25 and all other time off peak $.22 this is winter thru May.

Is that PG&E? If your goal is cost savings, using the PW during off peak is not going to save you any money on these winter rates. However, if your goal is just not use the grid than you should used self powered or balanced

 

[Merrill]

Is that PG&E? If your goal is cost savings, using the PW during off peak is not going to save you any money on these winter rates. However, if your goal is just not use the grid than you should used self powered or balanced

So if I use self powered I can run on the Powerwalls and not draw grid power.

 

[getakey]

So if I use self powered I can run on the Powerwalls and not draw grid power.

pretty much what self powered means

 

[jjrandorin]

So if I use self powered I can run on the Powerwalls and not draw grid power.

You might want to take a look at what tesla describes the modes as:

Powerwall Modes | Tesla Support

Powerwall is configured to meet your home’s specific energy needs. Use the Tesla app to monitor and manage your solar system’s performance with features and control modes such as Backup Reserve, Self-Powered and Time-Based Control.

www.tesla.com

yes, self powered mode prioritizes using your powerwall power to power your home, till it drains your batteries down to your reserve. It makes no allowances for "peak TOU time" or anything else. In self powered mode, your home will run off your batteries until it either hits the reserve you set, or the PV system comes up and provides enough power to both run your home and fill your batteries.

Since self powered mode prioritizes "using as little grid as possible" that sounds like what you are describing you want, but since you also mentioned in other posts "Time of use, peak time 4-9pm" you would need to decide what you really want.

Its entirely possible for self powered mode to run your home off batteries during a cloudy morning (for example) and not "save some for peak time". Its my opinion that anyone using self powered mode that is on a TOU plan needs to be prepared to micromanage reserve settings, etc.

Based on things you have posted before, Its my opinion this would not be a good fit for what you want.... but it does exactly what you say you want in this thread, which is "use the grid as little as possible" (while ignoring completely any and all time of use settings etc).

 

[arnolddeleon]

I run in "balanced" mode to achieve something similar to what you want. A couple "tricks". You can "lie" about your TOU rates. Set the peak for the times that you want the Powerwalls to run for sure. This could just be the true peak hours. Then you include some of the time that is normally off peak and call it "part peak". The system will try to cover those next if it thinks it will have energy stored to cover them. You can also adjust your reserve up and down to encourage/discourage more battery use.

For example I'm currently still in PG&E winter rates. I don't even have have peak hours right now. I only have part peak from 5-8 pm on Weekdays. The way I have the Powerwall configured for weekdays is as follows:

Part peak: 3-5 pm (this is anticipating the summer peak rates but I'm comfortable setting it as part peak because I generally have enough production to cover)
Peak: 5-9 pm (I want the Powerwalls to run for sure, covers winter part peak and summer peak)
Part peak 9pm to midnight: This is encourage to Powerwall to cover this part if it can
Off peak: The rest of the time.
Reserve: 10% (I'm comfortable that I have enough generation during spring/summer and probably early fall)

What I've observed is the system in balanced mode will discharge throughout the off peak period if thinks it will have enough energy to cover and enough time to charge up. If the system "thinks" it can only cover part of the off peak it will bias the time so it closer to the generation time. For example if the system "thinks" it has about 4 hours capacity and it is midnight and it thinks generation starts at 8:00 am it will stop discharging at midnight and start 4:00 am to try to be at the level at 8:00 am when there real generation. Of course this is based on observations of the current system. I'm likely wrong on some of the details because Tesla doesn't actually tell us the algorithm it uses and tweak it.

 

[Merrill]

You might want to take a look at what tesla describes the modes as:

Powerwall Modes | Tesla Support

Powerwall is configured to meet your home’s specific energy needs. Use the Tesla app to monitor and manage your solar system’s performance with features and control modes such as Backup Reserve, Self-Powered and Time-Based Control.

www.tesla.com

yes, self powered mode prioritizes using your powerwall power to power your home, till it drains your batteries down to your reserve. It makes no allowances for "peak TOU time" or anything else. In self powered mode, your home will run off your batteries until it either hits the reserve you set, or the PV system comes up and provides enough power to both run your home and fill your batteries.

Since self powered mode prioritizes "using as little grid as possible" that sounds like what you are describing you want, but since you also mentioned in other posts "Time of use, peak time 4-9pm" you would need to decide what you really want.

Its entirely possible for self powered mode to run your home off batteries during a cloudy morning (for example) and not "save some for peak time". Its my opinion that anyone using self powered mode that is on a TOU plan needs to be prepared to micromanage reserve settings, etc.

Based on things you have posted before, Its my opinion this would not be a good fit for what you want.... but it does exactly what you say you want in this thread, which is "use the grid as little as possible" (while ignoring completely any and all time of use settings etc).

Thanks for your input, I have read everything about self powered and still not sure if I should just run the Powerwalls longer on timed based or do self powered. The difference between peak charge and off peak is minimal so not saving much by just running the batteries from 4 to 9.