Leveraging "Time of Use" Rates

[UCIBtheG]

See the section below from the SGIP Handbook, it clearly states that stand-alone systems are eligible. For residential systems, I believe the requirement was only that they be fully discharged 52 times per year for the 5 year period. I don't remember seeing a requirement that they be recharged using PV or renewable power. Do you see something in the Handbook backing up Swell Energy's claim?

At this stage, I have a $500 deposit down toward the PowerWall, ordered through Tesla. Tesla allowed for hinging the PowerWall purchase on obtaining the SGIP incentive. I plan to use it for TOU arbitrage for the foreseeable future. I'm hoping to get this cleared up for anybody else in the same boat as me. There is a lot of confusion about the whole program and how it works in my opinion.

5.3 Eligibility Requirements for Energy Storage Projects Energy storage projects may be stand-alone or paired with generating systems and must be capable of discharging fully at least once per day. Energy storage systems paired with wind generation must have the ability to handle hundreds of partial discharge cycles each day. Residential energy storage projects, whether stand-alone or paired, must comply with additional requirements specified in the Residential Energy Storage Eligibility Affidavit designed to ensure that all residential energy storage systems participating in the SGIP will be used for more than just back-up emergency purposes.

 

[MelaniainLA]

So let’s resurrect this thread.

i just got 3 free red Powerwalls installed from the referral program. I’m in SCE territory on TOU-D-PRIME rate plan without solar and have 2 Tesla EVs. My Powerwalls are set to time of use to do some energy arbitrage.

During the 4-9pm peak time period for SCE, I only use 15% of the Powerwalls’ energy (which was stored using cheap power at off peak rates). Since I have 85% remaining, would I be able to sell that cheap power back to the grid at PEAK rates, profiting $300+ a month from the transaction? Is there a setting for this? Does it happen automatically?

 

[Need]

So let’s resurrect this thread.

i just got 3 free red Powerwalls installed from the referral program. I’m in SCE territory on TOU-D-PRIME rate plan without solar and have 2 Tesla EVs. My Powerwalls are set to time of use to do some energy arbitrage.

During the 4-9pm peak time period for SCE, I only use 15% of the Powerwalls’ energy (which was stored using cheap power at off peak rates). Since I have 85% remaining, would I be able to sell that cheap power back to the grid at PEAK rates, profiting $300+ a month from the transaction? Is there a setting for this? Does it happen automatically?

I am pretty sure you can't. Because basically you are buying (charging) the powerwalls from SCE at the lowest rate and then want to sell the energy back to them at the highest rate. I think in order to get into NEM, you have to generate your own energy and not buy from SCE at low rate, but I could be wrong! And it is not $300 profit. It is $300 credit that you have to use (to offset your usage) before the end of the 12 months. $300 credit is more like $10 profit. I had $1800 credit at the end of my 12 month (with solar) and I got like $70.

But it is great to have 3 Powerwalls as you get backup power for days when SCE start to shut off power with the high wind!

 

[Ampster]

I think all you could do would be charge your PowerWalls at the least expensive rate and un your house loads off the Powerwalls to avoid the highest rates. An analysis of your consumption patterns could tell you if there is enough capacity to do that. I presume because the installation is behind the meter, Tesla only pulled a building permit and did not have to get permission from SCE.
I don't know what the settings would be to accomplish what I described. After doing the analysis you may find that you could install enough solar to reduce your bill completely. Depending on the math you might be able to self consume your solar generation. Or you could apply for a Net Energy Metering agreement if that makes economic sense.
What ever you do, I would not charge you Teslas from the PowerWalls unless you need to be cause it is much more efficient to charge directly from the grid at the lowest rate because of the energy lost going in and out of the Powerwalls. Also you would be needlessly be reducing their life.

 

[RE Insider]

@ MelaniainLA - Thanks for resurrecting this post! Three FREE PowerWalls, that's pretty cool. So if Tesla correctly installed your system, you should be able to draw up to 40.5 kWh from your battery between 4-9pm rather than paying Edison 38/27 cents (weekdays/weekends). Did Tesla ask you to sign Edison's NEM agreement? I can provide you a break out of your energy consumption for the past 12 months (see example - just click here - Authorize Access to Utility Data (powered by UtilityAPI)


Source - Powerwall Time-Based Control | Tesla Support

 

[Ampster]

Did Tesla ask you to sign Edison's NEM agreement?

Why do you think a NEM agreement would be required for a behind the meter battery? If I understand the OP correctly there is no solar and Tesla would not configure the Powerwall to sell back to the grid.

 

[MelaniainLA]

Why do you think a NEM agreement would be required for a behind the meter battery? If I understand the OP correctly there is no solar and Tesla would not configure the Powerwall to sell back to the grid.

Yeah so that's what I am wondering... I don't have solar and while I am using the Powerwall battery during peak time, I even see sometimes the power going back into the grid, but at a limited level.

Since I have 3 Powerwall and only use 10-15% of that combined stored energy during peak-time, what I'd really love to see if whether I can buy cheap power off-peak, use 10-15% during peak time to run my house, and then sell the rest back to the grid using SCE's net metering policy, at a profit... I did have to get a Permission to Operate from the utility and certify as a "producer," even though I don't have solar, so I wonder if that's possible, or even if that's automatic after the Powerwall learns our usage habits?

Thanks!

 

[Havoc]

I have a 8kW solar installation that I purchased back in 2003. I just bought an MS which will be charged from home, and I expect to buy a second EV for my wife sometime in 2020.

I'm on PG&E's E-6 TOU tariff that has a peak period between noon and 6PM (1PM and 7PM during daylight savings time). Other possible TOU tariffs are ETOU-A, ETOU-B, ETOU-C3, EV2-A and EV-B. After looking at each of them, the logical replacement is EV2-A which is works very well for customers with an EV plus solar. However, the big issue with EV2-A is that the off-peak rate runs from midnight to 3PM, so much of my peak generation (most of which is a PG&E credit) will be at the off-peak rate. The difference is significant: EV2-A off-peak is 16c/kWh and peak E6 is 37c/kWh (April through October). In addition, peak rates with EV2-A are 4PM to 9PM, also a big hit to my solar credits from PG&E. After doing the calculations, it appears staying on E-6 should be the best choice for me.

However, E-6 is going away in 2022. PG&E also wants ditch ETOU-A and ETOU-B in 2022 and covert all TOU customers to ETOU-C3 which has higher rates than any other TOU tariff - except EV2-A and EV-B. I think EV-B is a non-starter if you have solar because of the separate meter for the EVs, so I thin I will have to move to EV2-A.

I'm not really sure that I have this figured out or missed something in my calculations. Has anyone done a similar analysis and come to any conclusions?

Another potential issue is that PG&E tried to have NEM revoked entirely in 2016 (as was done in Hawaii and Nevada) and they will probably try again in 2022. If they succeed, everything changes and new residential solar dies - as it has done in the two states I mentioned.

 

[brucet999]

I think EV-B is a non-starter if you have solar because of the separate meter for the EVs, so I thin I will have to move to EV2-A.

Why would a second meter affect your PV? Presumably, the second meter feeds only the EV chargers, so would be unaffected by PV, which is connected on the main service entrance panel. I would assume that the main service would be on a different billing class than the EV meter.

 

[Havoc]

What I want is a system where I can use the PV for the home and also charge the car from the PV (via net metering). That's EV2-A, not EV-B.

With EV-B, PV can only be connected to the home meter or the car charging meter - they are separate systems. I did ask PG&E about using virtual net metering (intended to allow multiple family dwellings with multiple meters to share a single PV installation) but they say you can't use EV-B or EV2-A tariff with virtual net metering.

So two problems. First of all, the home uses a lot more electricity than the car (about a 2.5:1 ratio) so connecting the PV to the home meter makes more sense. Secondly, the car is charged at night when PV is inactive, so EV-B is not a good option (for me) unless a battery storage system (such as a Powerwall, Sonnen, LG Chem RESU, Pika, etc.) is installed also. Also, given the upcoming rate changes in 2022, a solar battery system would save much more money on the home meter than the car meter by time-shifting self consumption.

It would be different if PG&E allowed you to charge a battery system from solar or the grid, but if you have PV it's one or the other. For some reason they frown on you taking electricity when it's cheap and feeding it back to them when it's expensive, so they have some complex requirements designed to prevent any sort of system configuration that would allow that to happen.

 

[Ampster]

Why would a second meter affect your PV?

It doesn't affect the PV per se but you can't use the PV production to offset the EV charging.

 

[JBailey895]

Hey, great thread here. I have NEM PV in San Diego (SDGE), and we just bought our second M3, and added HVAC last year. Our PV system is only 6Kwh, and we were almost net zero before the HVAC and new M3, so I expect to be back in the red again next true-up (Sept). Wondering if I should wait until Sept to see how bad it is, or is there a way to monitor generation vs. usage to adjust accordingly? Sorry, kinda a newb to the concepts. Thanx for any advice.

 

[wwu123]

Hey, great thread here. I have NEM PV in San Diego (SDGE), and we just bought our second M3, and added HVAC last year. Our PV system is only 6Kwh, and we were almost net zero before the HVAC and new M3, so I expect to be back in the red again next true-up (Sept). Wondering if I should wait until Sept to see how bad it is, or is there a way to monitor generation vs. usage to adjust accordingly? Sorry, kinda a newb to the concepts. Thanx for any advice.

I'm in PG&E territory, but it looks like SDGE also supports monitoring your consumption at your utility meter with an HAN device - basically you buy a 3rd-party Zigbee wireless device that reads your meter and logs the data to a portal. Rainforest Eagle is the reasonably priced ($99) device I use with PG&E that is on SDGE's certified list as well, slightly buggy and quirky but works for the price.

Now reading at the meter is usually your "net" consumption, but Rainforest can pipe your net consumption to another portal like pvoutput.org. If you can feed any PV generation data from your array as well, you can also back out actual household consumption vs actual generation. From there you might be able to intuit major appliances and loads that you can cut back or time-shift to more advantageous times of day.

There are other load-sensing devices that can attach to branches of your circuit panel to give more granular consumption data, but they're more complicated to set up, and the new wave of AI-based ones that claim to identify and model invidual appliaces and loads, well, they don't seem to be that intelligent yet, esp with PV.

 

[JBailey895]

Thanks, I do have a Zigbee to show generation info through Solar Edge, but I don't have anything to compare consumption. I know with two M3's and the HVAC, our otherwise glorious $20/yr electrical bill is going to change, a lot.

 

[turtlebud]

I'm one of the lucky ones that got in on the PGE TOU6 plan and am not looking forward to when it expires.

A few years ago, PGE did a pilot program with chargepoint (and maybe some other companies) that enabled a virtual second meter by linking your chargepoint home charger to PG&E and charging all that usage from that as a second meter (effectively an EV-B). I personally thought it worked pretty well so I was disappointed to find that after the pilot ended, they had no plans to continue it.

 

[RE Insider]

Hey, great thread here. I have NEM PV in San Diego (SDGE), and we just bought our second M3, and added HVAC last year. Our PV system is only 6Kwh, and we were almost net zero before the HVAC and new M3, so I expect to be back in the red again next true-up (Sept). Wondering if I should wait until Sept to see how bad it is, or is there a way to monitor generation vs. usage to adjust accordingly? Sorry, kinda a newb to the concepts. Thanx for any advice.

@JBailey895 - If you have an online account with SDG&E, you should be able to monitor "net" daily/monthly usage.

 

[JBailey895]

Thanks RE, I do get online billing showing monthly useage and generation, so I guess that should be adequate data, but not sure how to break it down for purposes of deciding if EV TOU-2 will be the "right call" or not, SDGE charges a monthly rate for the reduced price of kW, so if I were close enough to "even", I'd be paying more for that rated tier, but I likely won't be able to cover, and the extra ~$150/yr would probably be justified, just need the data to confirm. .