Powerwall 2: SGIP/Incentives

[abasile]

@Kanting The CPUC FAQ also says the following in the energy duration section: "Note also that energy storage incentives are reduced as the rated duration of the energy storage system increases. Most energy storage systems are rated for a given number of hours of continuous discharge." This is why I was referencing the 5 kW continuous discharge rate of the Powerwall 2 as supposed to the AC rating of one's PV system.

Right, so the highest possible rebate would accrue to a battery system that has a lot of storage (kWh) and can discharge at the highest possible rate (kW). Being able to fully discharge in less than two hours (which the Powerball 2 cannot do) is ideal, and 2-4 hours is second best.

This makes sense in terms of maximizing potential grid services. Going forward, the state (CA) would like our home batteries to be available to the grid upon request, in peak usage scenarios where thermal (fossil fuel) "peaker" plants would have otherwise been required. I haven't yet studied the specifics of this, however.

 

[ValueAnalyst]

All,
I haven't been following the Powerwall developments or monitoring the threads here at all. I'm just including the following text from an e-mail that I received from my Solar installer (not Solar City). My system was installed in February 2016. It looks like they have some kind of agreement with Tesla to install Powerwalls...

Dear Homeowner,

As you already know the 2017 SGIP Home Battery storage rebate is approved and will be open for very short period of time.
If you are interested in home energy storage and have not applied for rebate, please let us know and we will provide you with best-guaranteed quote for the battery including Tesla PowerWall 2.0. We carry all brands of home storage batteries and are a Certified Tesla Installer

The Application Deadline is May 1 and it will take only a few days. This is one of a kind opportunity to get this state rebate. The program has a high demand each year.

The most popular storage option is the Tesla PowerWall 2.0.

The Tesla PowerWall 2.0 is a 14kW Battery. See the Spec Sheet attached
The cost for you is 12,500.00, installed turn key
The estimated SGIP Rebate is going to be $7,000.00. This is not a guaranteed rebate. We will submit all the paperwork on your behalf and if you don't get the rebate then you don't have to go ahead.
You can potentially also qualify for the 30% tax credit to the cost after the rebate.
Cost after rebate: $5,500.00 (Before Tax Credit)

This is incredible. Why wouldn't all California residents do this?

 

[ValueAnalyst]

First, you should size your solar for you total usage, including EV charging, corrected for TOU credits and net metering rules like NEM 2.0 Non-Bypassable Charges. What I'm trying to say here is that it is more cost effective to aim for close to zero net dollars per year than net zero kWh per year.
Second, PowerWall cannot offset or reduce your usage, it can only shift it to a different time period, while losing a little energy in the process. PowerWall is useful to either reduce the billable charges from the utility, or to keep running through utility power outages, or both.

Does powerwall "reduce the billable charges from the utility" enough to pay for itself?

 

[Ulmo]

This is incredible. Why wouldn't all California residents do this?

Hmm. I submitted my SGIP paperwork already, but didn't yet sign the installation document, because I want to know the estimated full price after project (things are tight for me during tax season). I'm still waiting for information about that. I'm not sure what the next step in the process is. Time to read 164 messages, I suppose.

---

Edit:

I’m starting to generate some questions:

1. Does the SGIP program count electric use that is sent out into the grid?
2. Does the SGIP program count electric use that is sent out to a non-critical loads panel? (I have my vehicle charging on the non-crititcal loads panel, in assumption I can always drive to a fast charger during outages.)
3. Does the power limit of the PowerWall reduce the maximum power draw of the critical loads panel during non-outages? (Such as can I use more than 15kW (edit: 10kW continuous) in a two PowerWall system when the grid is still working? I don’t know how I’d achieve that, but it’s still worth asking.
4. Wow: I could have everything in the house turned on, and only two PowerWalls would supply it all (power-wise; they’d still run out of energy at some point); am I reading that correctly? I added most of the power-hog users here and it only came to 9kW (the car is not on the critical loads panel).
   
5. I need to verify that 7500 watts is the power rating.
6. I need to figure out if the $7,000 max SGIP benefit is per PowerWall or for the total system, and if it is a max for that installation or for all our installations, and what the numbers are. I'm sure it's somewhere in this thread ...

It would probably be better to use a low amperage 240V circuit if you want to charge your car from the PowerWall when the grid is down. Ideally you would be taking the power directly from the solar and they normally rely on the utility transformer to provide the 120V current because they don't connect to the neutral. The DC PowerWall with SolarEdge inverter requires an external auto-transformer to balance the neutral and supply 120V loads when the system is islanding.

I agree that automatic load shedding is not a major concern. However, it will be interesting to see how Tesla handles overload situations. Maybe send out a notification when it does overload and shut down, with a request to turn off higher power loads before restarting.

I'd be horrified if that's the best the programmers come up with, although of course that would be a reasonable error step if that actually occurred; some sort of noise that buzzed in the kitchen to tell you you are approaching full use with error messages about it in an effort to get you to reduce your use before shutdown would be more appropriate. Of course, it would need an adjustment for the warning limits, since every user has their own triggers in their own homes according to what kinds of loads they have. It's expensive to make such a system without using smartphone apps, and smartphone apps aren't reliable in an electrical outage; hmm -- perhaps the smartphone app would have a direct TCP/IP connection to the inverter within the local LAN ethernet (over wifi of course), bypassing any need for the Internet to be connected at all, and all you have to verify is that the wifi and other home routers are on the critical loads panel. But, iPhone would disconnect from the LAN if the Internet is down. Lots of little quirky problems in there. A dedicated device for $20 to place in your kitchen that connects to local wifi and is specifically programmed to not care about Internet connectivity (and connected directly over the LAN to the PowerWalls) would do the trick, as far as I can tell.

Tesla Power 2 is AC, they discontinue DC Powerwall.

I assume that this merely means:

• Cost savings are no longer available by getting DC-only version for those systems where the AC components of the PowerWalls would never be used.
• Even in systems where the AC components would never be used in the "AC" PowerWall version, all the same capabilities would be available as in the DC only PowerWall version
• The engineer would just update the part number, price, size, hookup locations, and settings, and nothing else would need actual engineering.

The only reason I care at all is that I spec'd the SolarEdge we installed to work with both PowerWall 1 and PowerWall 2, and I believe that it would work with either the PowerWall 2 DC or AC version. I believe that it doesn't matter anyway because the PowerWall 2 AC version exceeds the capability of our SolarEdge (in terms of power rating for two PowerWall 2's (especially considering the SGIP increased incentive for faster discharging (which seems like a good idea for what the SGIP program is attempting to achieve*))) and Tesla engineers are not proposing using our SolarEdge as the hook up point for this and other reasons, so it becomes a moot point. It's just idle curiosity. I generally like the direction Tesla went by eliminating the DC only version because of this since it simplifies the product lineup and engineering, however, it does boost my long term lingering fear that no one will ever design an efficient DC-only path for the DC-only components of the home electrical system (solar panels, batteries, car charging).

* I am really excited that the SGIP program is thinking in these terms and that Tesla is working with them; grid services is something that has been laggard at least in the home marketplace, and this seems like it will stimulate it to come to significant market existence. I've been saying something like this needs to exist for many decades, and it's finally coming together.

---

Bookmarks for myself for when I return to this thread and have time to muddle through equations used by tax programs: Start reading about some analysis of the SGIP programs at the following posts:

• Powerwall 2 "waiting list"
• Powerwall 2 "waiting list"

 

[abasile]

1. Does the SGIP program count electric use that is sent out into the grid?

According to my contact at Pick My Solar, you can't use a home battery to supply energy to the grid unless the utility specifically requests access to your stored energy during a peak load scenario. I believe they mentioned that a new program starting in 2018 will enable utilities and home battery owners to agree to this. This came up because I asked if I could store energy from PV generation during "off peak" hours, then discharge it into the grid during peak hours to obtain the highest possible value for the energy via net metering. Obviously this would be a substantial benefit to the homeowner, given that net metering essentially pays retail rates. But I'm sure the utilities would argue that it'd be too generous, at the expense of other ratepayers.

2. Does the SGIP program count electric use that is sent out to a non-critical loads panel? (I have my vehicle charging on the non-crititcal loads panel, in assumption I can always drive to a fast charger during outages.)

As long as you're self-consuming the energy, I don't think this matters at all. My assumption is that use of the battery is tracked by the battery system itself.

3. Does the power limit of the PowerWall reduce the maximum power draw of the critical loads panel during non-outages? (Such as can I use more than 15kW (edit: 10kW continuous) in a two PowerWall system when the grid is still working? I don’t know how I’d achieve that, but it’s still worth asking.

During non-outages, the critical loads panel would have access to grid electricity, so it shouldn't be limited by what the battery can provide. Consider the scenario where the grid is up, but the battery has been drained for whatever reason. That should have no effect on your ability to use circuits that are connected to the critical loads panel.

4. Wow: I could have everything in the house turned on, and only two PowerWalls would supply it all (power-wise; they’d still run out of energy at some point); am I reading that correctly? I added most of the power-hog users here and it only came to 9kW (the car is not on the critical loads panel).

Yes, 5 kW continuous power per Powerwall isn't bad! Since we don't have air conditioning (at least at this point), a single Powerwall would power everything we have except the EVSE.

5. I need to verify that 7500 watts is the power rating.

The most important number is probably 5 kW continuous.

6. I need to figure out if the $7,000 max SGIP benefit is per PowerWall or for the total system, and if it is a max for that installation or for all our installations, and what the numbers are. I'm sure it's somewhere in this thread ...

The rebate is computed based on the total storage and power in the overall system. I'm not sure about multiple installations, though I'd assume (but haven't checked) that you could submit separate SGIP applications for different service addresses.

 

[Ulmo]

2) As stated in 1) The rebate is on a sliding scale and only goes down as budgets are used up. The later one files, the less likely you get the maximum rebate. There are 5 steps for the rebate amounts.

Step 1: $0.50 / watt hour
Step 2: $0.45 / watt hour
Step 3: $0.40 / watt hour
Step 4: $0.35 / watt hour
Step 5: $0.30 / watt hour

At 13.5 Kwh for the Powerwall 2, this would max out the Step 1 rebate at $6,750

I'm not sure if Tesla, which manufactures batteries and PowerWalls in Nevada, but has manufacturing in California for their EV's and engineering also in California and possibly some headquarters taxation localities in California as well, would get the 20% in-state manufacturing incentive over that $.5/wh (step 1) (SGIP handbook page 23 paragraph 3.1.3) (is this giving Tesla a boost because Fremont business or a screw you because Nevada business; it's hard to imagine the State didn't consider Tesla when writing that piece and already has a particular interpretation in mind). I'm not sure how to calculate the 20% in bureaucrateze, but if I just multiply by .2, that's $1,350 per battery, which is $2,700 for two, not an insignificant little add-on.

According to my contact at Pick My Solar, you can't use a home battery to supply energy to the grid unless the utility specifically requests access to your stored energy during a peak load scenario. I believe they mentioned that a new program starting in 2018 will enable utilities and home battery owners to agree to this. This came up because I asked if I could store energy from PV generation during "off peak" hours, then discharge it into the grid during peak hours to obtain the highest possible value for the energy via net metering. Obviously this would be a substantial benefit to the homeowner, given that net metering essentially pays retail rates. But I'm sure the utilities would argue that it'd be too generous, at the expense of other ratepayers.

I certainly see your final point.

I'm curious if this applies to my non-critical loads panel which is within the home but is connected to the portion of the electrical system that sends stuff out on the grid, since the boat load's share of my use is through EV charging in the non-critical loads panel. If it's just about sticking a collection of measurement devices on the wires so that I can document my in-home use, that would be both inexpensive and easy, and this wouldn't bother me; it would bother me if it required expensive measurement devices. If the measurement device is the demarcation meter between PG&E and the home, then that's easy: PG&E already has a "smart meter" plugged in and working at that demarc, and that would be an easy way to see if I'm sending power to grid or not. Since the sun doesn't shine in the night, that makes this easier; I'd be more miffed if I was charging my EV during peak evening PG&E rates while my huge imaginary windmill in my back yard was giving lots of power, but less than my EV charging rate, so I'm drawing from the battery, and the program claims that that wouldn't apply, but then, even in that imaginary situation, it only wouldn't apply as far as there was excess, so theoretically ... ok, I gave up describing this imaginary situation (includes thoughts such as excess wind power given to grid, battery use discharge rates, etc.).

As long as you're self-consuming the energy, I don't think this matters at all. My assumption is that use of the battery is tracked by the battery system itself.

That would answer some of my prior question if so. So, to compare to the easy solar situation: Solar charges battery in day. (That's the problem being solved: solar is in day.) Evening and night comes, and I use the bejeezes out of the battery, charging my car. Full benefit. But, how would the benefit know that I wasn't not charging my car and instead sending it all out to grid?

---

SGIP handbook page 32 paragraph 4.2.5 is entitled "System Sizing for Projects without Peak Demand Information". Just that title plus a quick skim of the contents where I saw the text "kWh" implies to me the following:

• This is the section where they talk about speed of discharge and how it applies to calculating the incentive.
• The PowerWall 2 has Internet connection, and software control, so therefore it could have Peak Demand Information, but that is entirely the choice of the utilities, the regulators, and the programmers at the manufacturer of the PowerWall 2 (they go by the name Tesla). There's no guarantee that the utilities or the regulators have made this information available to the Tesla programmers, and the handbook conveniently leaves out any mention of a requirement of them to do so.

I wrote that thinking "Peak Demand Information" was their inaccurate name for "grid services", but then I realized it meant customer peak demand from the grid (which is never my assumption since I think in terms of a post-utility-is-the-only-generator world in which Peak Demand does not mean that, but it of course is the prejudice of the old farts running the existing system, which is odd, since it violates facilities that have co-gen from decades past (is that the principle that the biggest users don't use handbooks, and instead hire lawyers to read the actual regs?)). I then re-read what I wrote with that in mind, and suddenly it occurred to me that my incorrect text is still correct as applied to my new interpretation: does the utility tell home users what their peak demand is? Now I feel like I'm in the weeds of paper work again. I hate this feeling. Grrrrrrr. I think I'm getting so far in the weeds I'm going to reduce this piece I wrote to minimum font size.

---

According to SGIP handbook page 37 section 5.2.1, I calculated PowerWall 13500Wh / 5000W = 2.7h ("in relation to the rated capacity" (i.e., calculated as if maximum draw)), and that means 50% of the incentive, so for the 13500Wh*.50*.50=$3,375 (two PowerWalls = $6,750), or if the California manufacturing incentive applies, 13500*.7*.5=$4,725 ($9,450 for two). That's quite a reduction.

 

[RubberToe]

This is incredible. Why wouldn't all California residents do this?

VA,
Well, my use case may be a bit different than most. I haven't even analyzed the SGIP rules as others here have. But here is my shot at explaining why I don't need any battery storage...

The house where we have solar panels installed uses about 12 kWh of electricity per day. Not much variance between winter and summer due to mild climate, and the water heater and furnace use gas. In the winter the 4.4kw system generates a bit more power than we use on a monthly basis. In the summer it generates about 2x the power we use. Because SCE has net metering, we only get charged for the "net" power we end up using. And since we always generate more than we use, the monthly bill from SCE is a flat ~$10. At the end of the year, we get a check back for about $70 for all the excess power that we generate. If we had battery storage, we could store some of the excess power. But with the net metering we have, there is no reason to do so. I would imagine most people don't generate as much as they use in total, or don't have net metering, which might push them to add some storage.

Without getting into an insanely high level of detailed analysis, perhaps someone could take a shot at explaining a use case or two of why someone would need to have battery storage?

Case #1: If you don't have net metering, I believe that even if you overall generate more power than you use, anytime that you are actually drawing power from the grid you may be getting charged for it. Do I have this right? In that case, if you can store PV generated power in a battery you can avoid the cost of pulling grid power, and the cost savings comes down to "what you pay for drawing grid power versus drawing power from the battery system, and the cost of the battery system".

Case #2: If you have very unreliable electric power, and want to use the battery as a backup source. Whether that is for only critical loads or running the full house are two separate cases I believe.

Case #3: You have an EV, and charging it uses lots of power during specific periods. This does tie in with Case #1 above too. In our specific use case, our EV's both only have 27kWh batteries. These only charge at the house maybe 10 times per month. On days we do charge, we draw more power than we generate, but the net metering allows us to offset that power draw with days that we generate more than we use. I would imaging if you have one or two Teslas and your use case is that you charge at night, then maybe you need at most somewhere around 120kWh of power to top them both off. If you don't have net metering, then you maybe can get low off peak rates for that 120kWh, or maybe you can't since it varies by utility. In Pasadena (municipal utility, not where the house is located), I'm paying $0.26 any time of day for delivered power. If I were charging two Teslas at 120kWh then my cost would be $31.20 every time I do that. Depending on how much you drive, maybe you do that 4-6 times per month. So the EV's cost $187 per month to run in electricity. If your PV system and battery storage can supply that, then you save $187 per month. The equation then becomes "What does it cost to do the PV and battery, or just add the battery to existing PV, to see whether it makes sense to offset the $187 I'm paying for EV charging?" Is that basically correct?

RT

And lastly (added), the ensuing required "deep dive" into the numbers that you see going on here is for each individuals specific use case, also taking into account their charges based on utility provider. The outcome of this being the "pay back" period of when they expect the installation cost of whatever they have installed to be exceeded by the cost of power they would have otherwise consumed.

Hopefully this isn't completely divorced from reality Apologies if it is

 

[ValueAnalyst]

VA,
Well, my use case may be a bit different than most. I haven't even analyzed the SGIP rules as others here have. But here is my shot at explaining why I don't need any battery storage...

The house where we have solar panels installed uses about 12 kWh of electricity per day. Not much variance between winter and summer due to mild climate, and the water heater and furnace use gas. In the winter the 4.4kw system generates a bit more power than we use on a monthly basis. In the summer it generates about 2x the power we use. Because SCE has net metering, we only get charged for the "net" power we end up using. And since we always generate more than we use, the monthly bill from SCE is a flat ~$10. At the end of the year, we get a check back for about $70 for all the excess power that we generate. If we had battery storage, we could store some of the excess power. But with the net metering we have, there is no reason to do so. I would imagine most people don't generate as much as they use in total, or don't have net metering, which might push them to add some storage.

Without getting into an insanely high level of detailed analysis, perhaps someone could take a shot at explaining a use case or two of why someone would need to have battery storage?

Case #1: If you don't have net metering, I believe that even if you overall generate more power than you use, anytime that you are actually drawing power from the grid you may be getting charged for it. Do I have this right? In that case, if you can store PV generated power in a battery you can avoid the cost of pulling grid power, and the cost savings comes down to "what you pay for drawing grid power versus drawing power from the battery system, and the cost of the battery system".

Case #2: If you have very unreliable electric power, and want to use the battery as a backup source. Whether that is for only critical loads or running the full house are two separate cases I believe.

Case #3: You have an EV, and charging it uses lots of power during specific periods. This does tie in with Case #1 above too. In our specific use case, our EV's both only have 27kWh batteries. These only charge at the house maybe 10 times per month. On days we do charge, we draw more power than we generate, but the net metering allows us to offset that power draw with days that we generate more than we use. I would imaging if you have one or two Teslas and your use case is that you charge at night, then maybe you need at most somewhere around 120kWh of power to top them both off. If you don't have net metering, then you maybe can get low off peak rates for that 120kWh, or maybe you can't since it varies by utility. In Pasadena (municipal utility, not where the house is located), I'm paying $0.26 any time of day for delivered power. If I were charging two Teslas at 120kWh then my cost would be $31.20 every time I do that. Depending on how much you drive, maybe you do that 4-6 times per month. So the EV's cost $187 per month to run in electricity. If your PV system and battery storage can supply that, then you save $187 per month. The equation then becomes "What does it cost to do the PV and battery, or just add the battery to existing PV, to see whether it makes sense to offset the $187 I'm paying for EV charging?" Is that basically correct?

RT

And lastly (added), the ensuing required "deep dive" into the numbers that you see going on here is for each individuals specific use case, also taking into account their charges based on utility provider. The outcome of this being the "pay back" period of when they expect the installation cost of whatever they have installed to be exceeded by the cost of power they would have otherwise consumed.

Hopefully this isn't completely divorced from reality Apologies if it is

Thank you so much for the detailed response. I really appreciate it.

Would you agree with me that net metering is declining in political popularity, so it's likely to be gradually phased out in most states? In that scenario, would you invest in a stationary storage system like the Powerwall especially if the cost came down substantially with version 3?

I expect this to be the case in 2018/19. Lower priced Powerwall v3 needed in states that scale back net metering. This is my base case.

I think for states that choose to extend/expand net metering, it makes more sense for Tesla to drive Solar+Powerpack at the utility scale.

 

[Ulmo]

This is incredible. Why wouldn't all California residents do this?

Correction: replace "residents" with "homeowners".

 

[Ulmo]

Thank you so much for the detailed response. I really appreciate it.

Would you agree with me that net metering is declining in political popularity, so it's likely to be gradually phased out in most states? In that scenario, would you invest in a stationary storage system like the Powerwall especially if the cost came down substantially with version 3?

I expect this to be the case in 2018/19. Lower priced Powerwall v3 needed in states that scale back net metering. This is my base case.

I think for states that choose to extend/expand net metering, it makes more sense for Tesla to drive Solar+Powerpack at the utility scale.

What if net metering continued but during the max solar period of day electricity was free, so you'd not get any net advantage? That would almost be the same as no net metering. Correction: it would be the same as no net metering. Anything even close to that would mean that shifting daytime generation to evening use periods would have some benefit, possibly enough to make a battery worth it.

Currently, net metering pays a huge amount for daytime solar generation because the daytime period used to be peak period and they still pay you at the outdated peak rates in the NEM contracts. If they adjusted the actual cost for daytime electricity, the cost of that time of day's electricity would become the new low, competing with graveyard as the cheapest electricity, and NEM wouldn't help as much, making batteries comparatively less unattractive, even to the point of being attractive, and would find more positive use cases overall.

It's impossible that a system needs provision A at point B, gets provision A at point C, can use provision D to move point C supplies to point B, and that D or equivalent doesn't happen (assuming a surviving system). If provision A is clean energy and we aren't just using hydro and wind, then point C is the sun, and provision D is a battery, and point B is night time. Legacy issues come in because we also get energy via non-provision A sources. There is a little doubt because provision A can also be served via wind and rain. But, both of those doubts have abundantly been answered by a huge amount of point C collection. Thus the question becomes who is using provision D, where, when, how, how much, etc.? Do utilities install batteries, or do we at home? It has to happen one way or the other (non-exclusively) in that system. Bear in mind that provision D could also be accomplished via worldwide superconductors of sufficient network to move sufficient point C sun-receiving area solar power into point B dark areas without the necessity of even a single battery. For the foreseeable future, though, we don't have such a superconducting connected network of sun collectors in place (of sufficient proportion). That means provision D is batteries.

 

[ab26]

I am contemplating of installing powerwall but was wondering the following: is there any savings / benefits from installing a powerwall if you already have solar (that is sized to net zero pull from grid) and are in the old NEM 1.0 program?

 

[MP3Mike]

@ab26 Probably the biggest benefit would be the ability to keep things powered up for a period of time even if the grid goes down.

 

[brucet999]

Received an email update regarding the SGIP yesterday from Solar City. It is requesting copies of utility bills required for filing for the rebate. One significant point in the email mentions that "Customers who are applying through the residential program are eligible for a rebate for up to two Powerwalls". Until now, I was not sure how many powerwalls (other than one) were eligible for the rebate.

Unfortuantely, the socalgas.com website has been down all weekend, so I am unable to get a pdf copy of my gas bill to send in to keep the rebate ball rolling.

OK. I give up. What in the world does your gas bill have to do with Powerwall?

 

[Ulmo]

Likewise with SGIP. I suppose I'll submit for it. I'm generally averse to applying for rebates that are intended to incentivize something that I would have purchased anyway. I can take the rebate and donate it to another sustainable energy cause, though.

If that's true, you might be an edge case where you'd prefer not to hassle with the paperwork. I just found it easy so I wanted to pass that along. It might get harder down the line, though -- they might have restrictions, more paperwork, audits -- who knows. For instance, we've already heard one person talk about certain inspections and how that relates to SGIP a little. Also, the engineers might make certain decisions that have nothing to do with what is optimal just based on SGIP eligibility.

 

[SolarFrank]

Is it possible to add both solar AND Powerwall(s) concurrently to get the SGIP rebate on our SCE electrified SoCal 3,300 sq. ft. two-store single family residence?

If so will Solar City FINALLY install on houses with Spanish tile roofs like ours so I can just have ONE contractor / vendor be responsible for BOTH the solar system AND Powerwall installations?

If not, what solar installers would you recommend for a 7kWh solar systemon a Spanish tile roof in Orange County?

Fortunately our roof faces almost perfectly south with zero shading... except for the occasional coastal low clouds & fog. Our monthly SCE usage averages around 800 kWh. Last month it consisted of:

• 201 kWh On peak
• 230 kWh Off peak
• 445 kWh Super off peak (mostly our Tesla Model S P85D charging)
• 777 kWh Total electricity usage this month

Should I place a Powerwall 2 order ASAP? If so, how many Powerwall 2's would I need power our entire home in case of a power outage? (Tesla's Powerwall website estimates I'd need 2 x 14 kWh Powerwall batteries)

From getting solar bids early last year for a 6.867kW kW (solar energy) system (21 x SunPower AC Module; E20-327-C-AC WHT) I'll need to upgrade our 200A Main Service Panel ("MSP") to a 225A "solar ready" panel... so wiring in a PowerWall shouldn't be much more work.

Will a new solar system be on NEM 1.0 or 2.0 ? If 2.0, what will our monthly SCE "connection fee" be?

Last year SCE Edison came out with GMA (Generation Meter Adapter) for the electrical panels that are in good shape and are in compliance with the local codes. So you may not need to change the main electrical panel because on this GMA you can install a solar system of maximum 15.6 KW. I can show you a photo from one of our installation to see how looks like but I'm getting an error when I tried to upload.
In the case of a power outage, you will need to modify the electrical system to install a sub panel for critical loads that will be powered by the battery in case of an outage, and a backup gateway which I'm assuming has also a transfer switch integrated.
You can withdraw 5000 W from the battery:
- hair dryer 1500W
-clothes iron 1500W
-vacuum cleaner 1500W
-desktop computer 500W
In 2.5 hours the battery will be empty.
So depends on what would you like to have a back-up for:
-led lights usually 9-13W each
-refrigerator 500-1000W
-laptop under 100W
-Tv 100-500W depends on the size
Power tools, pool pump, AC units and kitchen appliances take a lot of power and probably you don't need power for all of them.
The diagram for Tesla Power Wall for back-up is attached.
Regarding installation of Spanish tiles are 2 types:
-clay one of cap and barrel and you can see the concrete between them
-clay one looks like the regular tiles but is a little bit longer and wider than regular tiles.
Solar system to be under the NEM 1.0 needs to be installed and interconnected before July 1st 2017. Depends on what kind of charging rates you are you will not get full retail price for the energy you generate and send to the grid. For example, at 1 PM you will sell the electricity to SCE at 20 cents but next day at 1 Pm you can buy it from them at 35 cents, this is just and example to understand how the NEM 2.0 works, the prices ar not SCE rates for charges/credit.

 

[brucet999]

I understand that the PowerWall is a cool idea, but in areas with reliable Grid power the need for backup is pretty small.
The battery's 14kWh capacity is too small to use for charging your Tesla.
To qualify for SGIP you must not use it to time-shift Grid power consumption from peak rates time to super off peak.

You would be limited to storing solar power, so the PowerWall's value is only its reduction of peak rates usage. What is the ROI in that? Maybe after SGIP rebate and 30% tax credit on the remainder, it does work out?.

 

[doubleohwhat]

I understand that the PowerWall is a cool idea, but in areas with reliable Grid power the need for backup is pretty small.

It really depends on the area you live in. For example, where I'm at, we have a very reliable grid. Non-weather related outages are incredibly rare. However, we're in a tornado and hurricane prone area.

Also, we have no net metering here. The local utility charges $5/month per installed kW of solar. They then buy back any extra generated electricity at (what works out to) roughly $0.03/kWh.

So it's worth it to have batteries to soak up any and all electricity that a solar array generates that is not immediately used.

 

[miimura]

OK. I give up. What in the world does your gas bill have to do with Powerwall?

This is from the SGIP web site:

The LA Department of Water and Power is a significant electricity supplier in Southern California, but those customers are also customers of SoCal Gas. There are also quite a number of municipal electric utilities in cities like Burbank, Pasadena, and Glendale, just to name a few.

 

[brucet999]

This is from the SGIP web site:

View attachment 224166
The LA Department of Water and Power is a significant electricity supplier in Southern California, but those customers are also customers of SoCal Gas. There are also quite a number of municipal electric utilities in cities like Burbank, Pasadena, and Glendale, just to name a few.

I know that soCalGas is not part of SCE, but what does gas have to do with Self Generation Incentive Program? As far as I know, no one has ever generated methane from a PV array or a windmill.

 

[miimura]

I understand that the PowerWall is a cool idea, but in areas with reliable Grid power the need for backup is pretty small.
The battery's 14kWh capacity is too small to use for charging your Tesla.
To qualify for SGIP you must not use it to time-shift Grid power consumption from peak rates time to super off peak.

You would be limited to storing solar power, so the PowerWall's value is only its reduction of peak rates usage. What is the ROI in that? Maybe after SGIP rebate and 30% tax credit on the remainder, it does work out?.

I calculated that if I charged the battery from my solar in the morning and discharged 10kWh every day during the Peak rate period, I could save $597/year off my annual true-up on the EV rate schedule. This is foregoing the credit for the Part-Peak generation and getting the credit for the Peak period, either avoided usage or actually pushing energy into the grid. The last two years that we've had 2 EVs, we've had to pay about $1,000 at true-up. So, after SGIP and ITC tax credit, it will definitely pay for itself.