What is the best setting to run your powerwalls

[Intense1]

I have a solar system as well as 4 Tesla Powerwalls and I am trying to come to terms with how I should be using Tesla's advanced mode option given my circumstances.

First let me explain. I am on a TOU (Time of Use) rate plan with the power company. I pay a peak rate of $.45 per KWh from 4PM-9PM and a standard rate of $.17 per KWh the rest of the time. The NESCR (Net Energy Surplus Compensation Rate), or rate that I get reimbursed for the excess energy I produce and send back to the grid about $.03 per KWh. (varies between $.02-$.03 depending upon month).

If I run in advanced mode and have it set for the house to shift to battery power between 4PM-9PM I am consuming power I produced from solar and avoiding the $.45 per KWH period. At 9PM the batteries cease providing power and the house switches back to the grid and when the sun comes up, excess power that my solar produces will flow to top off the batteries before going to the grid. Then once the batteries are full, the overage goes back to the grid. My solar produces @ 85KWh of energy per day and consume @65 KWh per day. It's notable that about 50% of my consumption occurs during the peak period of 4PM-9PM.

So, basically I avoid paying the $.45 per KWH for 5 hours a day and of course lose the $.03 per KWH for the energy going into recharging my Powerwalls. (I know there's another 10% loss due to the AC/DC conversion process but again that would be computed at the $.03 rate). This seems like the best way to go, right?
Or,
Should I have it set to run all night? Come on at 4PM to avoid Peak rates and continue to run until 4, 5, 6, or 7AM and use all of my daily excess KWh and a large portion of my Solar to recharge the batteries during the day at the $.17 rate?

Setting aside the cycles on the batteries, how should I be doing this to optimize cost savings?

 

[holeydonut]

I have a solar system as well as 4 Tesla Powerwalls and I am trying to come to terms with how I should be using Tesla's advanced mode option given my circumstances.

First let me explain. I am on a TOU (Time of Use) rate plan with the power company. I pay a peak rate of $.45 per KWh from 4PM-9PM and a standard rate of $.17 per KWh the rest of the time. The NESCR (Net Energy Surplus Compensation Rate), or rate that I get reimbursed for the excess energy I produce and send back to the grid about $.03 per KWh. (varies between $.02-$.03 depending upon month).

If I run in advanced mode and have it set for the house to shift to battery power between 4PM-9PM I am consuming power I produced from solar and avoiding the $.45 per KWH period. At 9PM the batteries cease providing power and the house switches back to the grid and when the sun comes up, excess power that my solar produces will flow to top off the batteries before going to the grid. Then once the batteries are full, the overage goes back to the grid. My solar produces @ 85KWh of energy per day and consume @65 KWh per day. It's notable that about 50% of my consumption occurs during the peak period of 4PM-9PM.

So, basically I avoid paying the $.45 per KWH for 5 hours a day and of course lose the $.03 per KWH for the energy going into recharging my Powerwalls. (I know there's another 10% loss due to the AC/DC conversion process but again that would be computed at the $.03 rate). This seems like the best way to go, right?
Or,
Should I have it set to run all night? Come on at 4PM to avoid Peak rates and continue to run until 4, 5, 6, or 7AM and use all of my daily excess KWh and a large portion of my Solar to recharge the batteries during the day at the $.17 rate?

Setting aside the cycles on the batteries, how should I be doing this to optimize cost savings?

I think the scenario you painted in the first few paragraphs is the best cost-saving approach. This is because there are conversion losses. For every 1.0 kWh you put into a Powerwall, you only get back about 0.85 kWh.

But for every 1.0 kWh you push back through your electricity meter, the assumption is you get back 1.0 kWh when you pull energy from the utility during off-peak at the same rate.

And as you described, you definitely want to export energy to the Grid from 4pm to sunset since you get the peak time credit. And you want to avoid the ghastly peak time energy from the PoCo through to 9pm.

FYI, in NorCal, the off-peak time for the latest plans (like the one I'm stuck on since I am solar-constrained on my roof) ends at 3pm and doesn't begin again until midnight. It's a crazy long time people need to try and duck using energy from the grid.

 

[Intense1]

I think the scenario you painted in the first few paragraphs is the best cost-saving approach. This is because there are conversion losses. For every 1.0 kWh you put into a Powerwall, you only get back about 0.85 kWh.

But for every 1.0 kWh you push back through your electricity meter, the assumption is you get back 1.0 kWh when you pull energy from the utility during off-peak at the same rate.

And as you described, you definitely want to export energy to the Grid from 4pm to sunset since you get the peak time credit. And you want to avoid the ghastly peak time energy from the PoCo through to 9pm.

FYI, in NorCal, the off-peak time for the latest plans (like the one I'm stuck on since I am solar-constrained on my roof) ends at 3pm and doesn't begin again until midnight. It's a crazy long time people need to try and duck using energy from the grid.

There is not Peak time credit, I just avoid not paying Peak time consumption.

 

[holeydonut]

There is not Peak time credit, I just avoid not paying Peak time consumption.

Your NEM and TOU rate forces a constant bank credit but charges you peak consumption? Man that's harsh.

 

[jjrandorin]

I have a solar system as well as 4 Tesla Powerwalls and I am trying to come to terms with how I should be using Tesla's advanced mode option given my circumstances.

First let me explain. I am on a TOU (Time of Use) rate plan with the power company. I pay a peak rate of $.45 per KWh from 4PM-9PM and a standard rate of $.17 per KWh the rest of the time. The NESCR (Net Energy Surplus Compensation Rate), or rate that I get reimbursed for the excess energy I produce and send back to the grid about $.03 per KWh. (varies between $.02-$.03 depending upon month).

If I run in advanced mode and have it set for the house to shift to battery power between 4PM-9PM I am consuming power I produced from solar and avoiding the $.45 per KWH period. At 9PM the batteries cease providing power and the house switches back to the grid and when the sun comes up, excess power that my solar produces will flow to top off the batteries before going to the grid. Then once the batteries are full, the overage goes back to the grid. My solar produces @ 85KWh of energy per day and consume @65 KWh per day. It's notable that about 50% of my consumption occurs during the peak period of 4PM-9PM.

So, basically I avoid paying the $.45 per KWH for 5 hours a day and of course lose the $.03 per KWH for the energy going into recharging my Powerwalls. (I know there's another 10% loss due to the AC/DC conversion process but again that would be computed at the $.03 rate). This seems like the best way to go, right?
Or,
Should I have it set to run all night? Come on at 4PM to avoid Peak rates and continue to run until 4, 5, 6, or 7AM and use all of my daily excess KWh and a large portion of my Solar to recharge the batteries during the day at the $.17 rate?

Setting aside the cycles on the batteries, how should I be doing this to optimize cost savings?

What utility is this? Its not SCE (or if it is, the understanding of what that 3 cent compensation rate is, is incorrect).

 

[ArizonaJon]

I suggest you use the Power Wall down to what reserve you feel comfortable with in case of a power failure. Your export is $0.03 correct? Your cost avoidance is $0.17 reduced by your battery efficiency. So at 85% efficiency (about what I also see) you net avoidance is about $0.145 per kWh. That is a lot better than the $0.03.

 

[yblaser]

This sure looks like SCE TOU-D-PRIME and if it is as jjrandorin says you may not be understanding how the billing works.

On each monthly bill you will have your current charges which includes some fees dependent on your plan plus the Non-Bypassable Charges (NBCs) which are about ~$0.03/kWh for every kWh you pulled from the grid that month. These costs you pay monthly.

The next section is tracked charges which will add up you usage/production and charge/credit you depending on which TOU period it was used. Depending on if you are a net energy user/producer they will charge/credit you for peak usage at +/- $0.42/kWh. Likewise with the off peak you get a charge/credit for +/- $0.14/kWh. These charges/credits for each TOU period are summed together and that value carried over each month.

If at the end of 12 months if you have a net positive ($) balance then that is what you owe. If you have a net negative balance you do not owe anything and they zero out the balance. At that point they look at the total kWh used vs produced over the last 12 months. If you used more kWh than you produced you still do not owe anything. If you produced more kWh than used then they pay you at the $0.03/kWh rate you mentioned.

It is hard to tell from a single month snapshot, but if you are a net energy producer with no net energy costs at the end of 12 months (i.e. they are paying you the $0.03/kWh for net production) then what you are doing is probably close to the most economical. If you pull from the grid you are essentially paying the $0.03/kWh in NBCs. If you pull from the powerwall you are avoiding the NBC, but reducing the solar going back to the grid to charge the powerwall that your are ultimately getting paid at about $0.03/kWh. It is near a zero sum at least when kWh costs are rounded to the nearest penny. If you include the powerwall roundtrip efficiency and cycling impacts it probably make pulling from the grid less costly unless you place any value in being self powered.

 

[Intense1]

This sure looks like SCE TOU-D-PRIME and if it is as jjrandorin says you may not be understanding how the billing works.

On each monthly bill you will have your current charges which includes some fees dependent on your plan plus the Non-Bypassable Charges (NBCs) which are about ~$0.03/kWh for every kWh you pulled from the grid that month. These costs you pay monthly.

The next section is tracked charges which will add up you usage/production and charge/credit you depending on which TOU period it was used. Depending on if you are a net energy user/producer they will charge/credit you for peak usage at +/- $0.42/kWh. Likewise with the off peak you get a charge/credit for +/- $0.14/kWh. These charges/credits for each TOU period are summed together and that value carried over each month.

If at the end of 12 months if you have a net positive ($) balance then that is what you owe. If you have a net negative balance you do not owe anything and they zero out the balance. At that point they look at the total kWh used vs produced over the last 12 months. If you used more kWh than you produced you still do not owe anything. If you produced more kWh than used then they pay you at the $0.03/kWh rate you mentioned.

It is hard to tell from a single month snapshot, but if you are a net energy producer with no net energy costs at the end of 12 months (i.e. they are paying you the $0.03/kWh for net production) then what you are doing is probably close to the most economical. If you pull from the grid you are essentially paying the $0.03/kWh in NBCs. If you pull from the powerwall you are avoiding the NBC, but reducing the solar going back to the grid to charge the powerwall that your are ultimately getting paid at about $0.03/kWh. It is near a zero sum at least when kWh costs are rounded to the nearest penny. If you include the powerwall roundtrip efficiency and cycling impacts it probably make pulling from the grid less costly unless you place any value in being self powered.

Yes, it is TOU-D-PRIME and it appears you and jjrandorin are correct, I have misunderstood how the biIling works. Thank you for your thoughtful explanation. That was very helpful.

 

[Intense1]

What utility is this? Its not SCE (or if it is, the understanding of what that 3 cent compensation rate is, is incorrect).

Indeed, you are correct. I completely misunderstood the billing process.