Welcome to Tesla Motors Club
Discuss Tesla's Model S, Model 3, Model X, Model Y, Cybertruck, Roadster and More.
Register

Solar and Tesla powerwall (help please)

DrDan123

Member
Aug 7, 2018
44
2
San Gabriel Valley
Hello all,
I was hoping some of you experts can chime in to help me out with my system. I'm not sure if I am running my system correctly to save as much energy as possible. Please help me out if possible

Last Dec 2019 I installed a 9.24 kWp system. Here is the breakdown of my sytem

Photovoltaic

Installation of (24) Canadian Solar 385
Installation of (1) SolarEdge 6000H-US (240V) [SI1])
Installation of (24) SolarEdge 400 Optimizers
Installation of (1) SolarEdge Cellular Monitoring Device

I also just installed 1 tesla powerwall (referral prize)


I currently own 2 Tesla vehicles (both 75D)

I noticed on my electric bill that I am using A LOT of energy. I understand that my cars are the bulk of the problem, but just wondering if I am charging them when I should be.

I live in LA County so I am getting my electricity from Edison and am currently on TOU-D-B plan

Here is the breakdown of the TOU D-B plan

Highest Rates: Weekdays 2-8 p.m.
Daily Basic Charge: $0.60 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: 18 cents from 8 a.m. to 2 p.m., and 8 p.m. to 10 p.m.
Super Off-Peak: 12 cents from 10 p.m. to 8 a.m.
On-Peak: 50 cents from 2 p.m. to 8 p.m.

Weekend Summer Rates
Off-Peak: 18 cents from 8 a.m. to 10 p.m.
Super Off-Peak: 12 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: 17 cents from 8 a.m. to 2 p.m., and 8 p.m. to 10 p.m.
Super Off-Peak: 12 cents from 10 p.m. to 8 a.m.
On-Peak: 27 cents from 2 p.m. to 8 p.m.

Weekend Winter Rates
Weekend Off-Peak: 17 cents from 8 a.m. to 10 p.m.
Super Off-Peak: 12 cents from 10 p.m. to 8 a.m.



I am considering switching from that plan to the new TOU D-PRIME rates. I'm sorry but I cannot copy and paste the rates. It can be found here

Time-Of-Use Residential Rate Plans

As of right now, I am on self-powered mode on the Tesla Powerwall, leaving 20% for Power Outages.

I currently charge either car during my super off peak hours which start 10pm

I have a swimming pool which has the pump running during the day (it's a must for my solar heating)


Should I switch to the TOU D-Prime? If so, should I be charging the cars when the sun is out (not during on-peak hours) while my solar panels are getting energy or during off-peak hours?

If you think I should stay on TOU-D-B, should I be charging the cars during the day (not during on-peak hours) or during super off peak?

Thank you so much for taking your time to help me. I am a completely clueless to this.
 

Gwgan

Almost a wagon
Aug 11, 2013
2,849
2,111
Maine
Paying the lowest price for car charging and using Powerwall to run the house during peak seems like the best option. Can your system support the house 2p-8p? Then I would stick to the grandfathered plan. Are you compensated for power fed to the grid? That makes it more advantageous to zero out peak grid consumpion.
I made spreadsheets and ran my own historic data before choosing a TOU plan and the end result was that cheap car charging was the single biggest factor.
 

power.saver

Supporting Member
Mar 4, 2018
506
511
Arcadia, CA
Should I switch to the TOU D-Prime? If so, should I be charging the cars when the sun is out (not during on-peak hours) while my solar panels are getting energy or during off-peak hours?

If you think I should stay on TOU-D-B, should I be charging the cars during the day (not during on-peak hours) or during super off peak?

TOU-D-PRIME is a good rate if you have an EV and PV with batteries, as you do. And if you have to run your pool pump during the daytime, then it will really help since Off-Peak is until 4pm. But once you switch, you cannot return to TOU-D-B again.

You will net less credits on TOU-D-PRIME since nearly all solar is Off-Peak, but the Off-Peak rate is the lowest of any rate SCE offers. So with two EVs and daytime pool pump, I think this would be your best choice. If your PW can cover the 5 hour peak period, you will have no peak charges. But that may be a problem if you have AC and use it during the Peak.
 

DrDan123

Member
Aug 7, 2018
44
2
San Gabriel Valley
Thank you so much for the answers. I believe my powerwall can cover the 5 hour peak period as we do not use the AC during that time, or try not to at least. I am using a lot of energy these days as my solar is not even close to covering what I use. I use anywhere from 1000-1600 KWH a month just on charging the cars.

@power.saver Should I customize the powerwall to Advanced -Time based control and use it for the peak periods or just keep it on self-powered?
 

cwied

Member
Jan 13, 2015
869
617
San Mateo, CA
If your solar does not cover your usage, you will almost certainly get the most savings by using time-based control in cost savings mode. Self-powered is mainly aimed at those who either don't have net metering or want to minimize their grid usage.
 
  • Like
Reactions: jjrandorin

hurjio

Member
Feb 3, 2018
128
41
Southern California
I would change your powerwall mode to time-based cost savings. I can't tell you whether you should change to TOU-PRIME, but my gut says no. You say you use a lot more energy than you can produce, but is that just overall or at any moment in time? Do you know if you export a lot of energy back to SCE, or is most solar energy consumed by the home and powerwall as soon as it's produced?
 

DrDan123

Member
Aug 7, 2018
44
2
San Gabriel Valley
I would change your powerwall mode to time-based cost savings. I can't tell you whether you should change to TOU-PRIME, but my gut says no. You say you use a lot more energy than you can produce, but is that just overall or at any moment in time? Do you know if you export a lot of energy back to SCE, or is most solar energy consumed by the home and powerwall as soon as it's produced?

@hurjio

I'd say overall I use more energy than I produce. This month and last month espeically, since AC runs a lot more than usual.

Do I know if I export a lot of energy back to SCE? I have no clue as I have no idea how to read my electricity bills. Again, and I apologize, I have no clue what is going on when it comes to this.

Is most solar enery consuded by the the home and powerwall as soon as it's produced? Again, I will apologize once more, I have no clue what is going on when it comes to this.

I was able to copy and paste this off my last electricity bill.

Your past and current electricity usage Your next billing cycle for meter ************* will end on or about 08/24/20
Electricity (kWh) Summer Season - Consumption
On peak 230
Off peak 304
Super off peak 1,211
Summer Season –Net Generation
On peak -191
Off peak -543
Super off peak -21
Total electricity usage this month in kWh 990


I calculated how much KWH I produced off my solar for the billing period, which came out to roughly 1600KWH produced

Keep in mind that I just got my power wall installed literally 2 days ago

@power.saver I actually live in Arcadia as well. Hi neighbor!
 
Last edited:

RoBoRaT

Zero Farts Given!
Nov 22, 2018
1,376
1,215
NorthSoCal
If your solar does not cover your usage, you will almost certainly get the most savings by using time-based control in cost savings mode. Self-powered is mainly aimed at those who either don't have net metering or want to minimize their grid usage.

I agree with @cwied.

@DrDan123, I turned on my system last year currently on my 12th month in SCE territory.

10kWp solar panels (Inverter 7.8 kWp due to inverter/panel ratio)

2 Powerwalls

Model 3 driven 35K mi/yr ; Model Y 12K mi/yr
and a house with 2 AC units

SCE TOU-D-B since PTO (12 months)

PW: Time Based Control; Cost Saving
20% Reserved for Outage (12 months)

We consume more than produced, but have $750 credit from arbitrage. Will not get compensated since I am net consumer.

On average NBCs are $25 per month.

See attached for reference, Lifetime since PTO Sep 2019.
Screenshot_20200813-113459_Tesla.jpg
 

miimura

Well-Known Member
Aug 21, 2013
6,161
5,753
Los Altos, CA
@hurjio

I'd say overall I use more energy than I produce. This month and last month espeically, since AC runs a lot more than usual.

Do I know if I export a lot of energy back to SCE? I have no clue as I have no idea how to read my electricity bills. Again, and I apologize, I have no clue what is going on when it comes to this.

Is most solar enery consuded by the the home and powerwall as soon as it's produced? Again, I will apologize once more, I have no clue what is going on when it comes to this.

I was able to copy and paste this off my last electricity bill.

Your past and current electricity usage Your next billing cycle for meter ************* will end on or about 08/24/20
Electricity (kWh) Summer Season - Consumption
On peak 230
Off peak 304
Super off peak 1,211
Summer Season –Net Generation
On peak -191
Off peak -543
Super off peak -21
Total electricity usage this month in kWh 990


I calculated how much KWH I produced off my solar for the billing period, which came out to roughly 1600KWH produced

Keep in mind that I just got my power wall installed literally 2 days ago
Since you just got the PWs, turn on Advanced - Cost Saving mode and see how it goes for a month or two. Like someone said above, once you leave TOU-D-B, you can't go back. If it looks like TOU-D-Prime will save you money it will still be there in the future.
 

power.saver

Supporting Member
Mar 4, 2018
506
511
Arcadia, CA
@power.saver I actually live in Arcadia as well. Hi neighbor!
Hi,

As everyone else has said, use Time-Based Advanced Cost Savings mode, and if you stay on TOU-D-B for now, set the Peak time as 2pm-8pm, and everything else as Off-Peak weekdays. Weekends are all-day Off-Peak. Don't set any Shoulder time.

If or when you switch to TOU-D-PRIME, change to Peak time 4pm-9pm, and everything else as Off-Peak, every day (weekdays and weekends). There is no Part Peak (shoulder) rate in TOU-D-PRIME, so don't set any Shoulder time.

The Shoulder, or Part Peak, does not work well in the PW and you are better served with only Peak and Off-Peak times.

Consider also that the Peak in TOU-D-B is 6 hours, but only 5 hours in TOU-D-PRIME. With only one PW, you should monitor closely how long your PW will power your house during the peak.
 

DrDan123

Member
Aug 7, 2018
44
2
San Gabriel Valley
@power.saver
@hurjio
@miimura
@RoBoRaT
@cwied
@Gwgan

I appreciate everyone's input on how I should run my system.

I've decided to switch to TOU-D-PRIME since the peak hours from 4pm-9pm is usually the hours we use less power. My wife is a stay at home so doing laundry, 2 ac units, swimming pool pump is all done before 4pm. I believe this is the best solution as the battery should be sufficient enough to cover those hours.

If I keep the powerwall at 20% for reserves, how long would that last to only cover the necessities? We would only need the fridge and a couple lights to get us by if it's a long power outage.

Is there any tax incentives or anything I should do as far as credits? This was a referral prize and paid $2500 for installation.
 

miimura

Well-Known Member
Aug 21, 2013
6,161
5,753
Los Altos, CA
Is there any tax incentives or anything I should do as far as credits? This was a referral prize and paid $2500 for installation.
If the Powerwall(s) are charged from solar, you can claim the ITC (26% in 2020) on your Federal return for any net cost, even if the hardware was a referral prize. You will probably get a 1099 for the prize, so the ITC on the installation cost will help offset the income tax on the prize.
 

About Us

Formed in 2006, Tesla Motors Club (TMC) was the first independent online Tesla community. Today it remains the largest and most dynamic community of Tesla enthusiasts. Learn more.

Do you value your experience at TMC? Consider becoming a Supporting Member of Tesla Motors Club. As a thank you for your contribution, you'll get nearly no ads in the Community and Groups sections. Additional perks are available depending on the level of contribution. Please visit the Account Upgrades page for more details.


SUPPORT TMC
Top