NEM 1.0, Power Wall and SCE is it worth it?

[robbyville]

Hi all,

First post, I've tried some searching and it doesn't appear that this has been asked to the extent I'm searching for so here we go...

I purchased my home with solar 3 years ago. We live in the Southern California Desert, where temps will easily be 110+ for extended periods of time well over 2 weeks in a row, but ultimately for up to 2 months and slightly longer over 100.

I have 27 panels, estimated at roughly 8.45KW.

When we first bought the home, the previous owner had SCE bills of roughly $50/yr, but he was single and older. We're a family of 3, I'm an ex-pat Canadian so we keep the house pretty cool (read AC on full tilt boogie). The first year our electric bill was around $650, then $1200, and then this past year ending March 2023 well over $3400.

I have owned a Model 3 long range from March 2022 as well. I put a lot of miles on it (30,000 in the first year) and charge at home 95% of the time starting at midnight. I could charge during the day much of the time but had thought that I shouldn't (advice on this?)

I recently had the system professionally cleaned and inspected, I'm told that everything is working properly with little degradation shown since original install in 2015.

Looking over my bills from SCE, I appear to be on NEM 1.0 which as I understand it makes sense since it would have transferred to me when the home was purchased.

So, assuming that all this is correct and that my bills will be legitimately in the $3k plus range per year, along with some savings by not being stupid, my ultimate question to make a short story long is: Does it make sense to invest in a Power Wall system while being on NEM 1.0, I'm not worried about power outages as they are quite rare so it would truly only be for saving on the annual bill.

Thanks so much for any advice and guidance!

 

[jjrandorin]

Kind of depends on if you were forced to be on a time of use plan or not, but if you are talking about from a financial perspective only (since you said "I am not worried about power outages") the answer is pretty much "No, not worth it for just that purpose".

 

[robbyville]

Kind of depends on if you were forced to be on a time of use plan or not, but if you are talking about from a financial perspective only (since you said "I am not worried about power outages") the answer is pretty much "No, not worth it for just that purpose".

Thank you! I don't believe that I'm on a time of use plan, at least I don't see anything in my billing that seems to indicate it other than at times breeching into Tier 2 pricing

I imagine I'm just incredibly surprised at the increase in my bill from year 2 to year 3. I understand that SCE increased rates dramatically but to have gone up by literally 300% seems awfully odd, even with the addition of the electric car. I was trying to estimate costs of charging but for some reason my phone app does not seem to include the "statistics" section where I can put in my electrical rates.

 

[jjrandorin]

if you are on NEM 1 with a regular tiered rate, and 1:1 net metering, thats basically the best circumstance you can be in, as it relates to solar in CA (its the same circumstance I am in currently). The cost of electricity has gone up quite a bit, especially tier 2 and 3 rates.

If you are not on a time of use rate, a powerwall is not going to help you save money at all. On NEM 1 with a tiered plan, the utility is your powerwall, especially if you dont care about power outages / being green etc.

A powerwall lets you use your solar power you generate during the day, at night, but if you are on a tiered rate it doesnt matter WHEN you are using your power, just how much you are using. You would spend 13-14k on a powerwall, and not really save any money.

Your EV has probably bumped you from tier 1 to tier 2 or tier 3 monthly rates, but buying a powerwall is not going to do a thing about that. Its also too late for you to add more solar without getting off nem 1 and onto nem 3, which would increase your spend (probably a ton, actually).

A bit of a longer answer than my last one, but its the same (lol). Cost estimates through SCE also dont work for me (im on NEM 1 and a tiered rate). They did right when I got a powerwall, and were trying to "helpfully" sign me up for a time of use rate, and every time of use rate increased my bill a minimum of $1200 a year over what I have.

I suspect that they dont show you rate comparisons if it shows that every rate they could offer you is more expensive than what you have, if what you have is a rate they dont offer anymore (like basically any tiered rate for a solar customer like it sounds like you have).

You can feel fairly confident that NEM 1 and tiered rates are very good, because they stopped offering them to solar customers in CA a while ago and wont let anyone sign up for what you and I have.

 

[robbyville]

Once again thank you! This is the in depth explanation that I think I needed. I checked on my wife’s Tesla app and it seems like her login as owner had the charging statistics for the car. I muddled around with the usage charges based on home charging and a blended rate of roughly .30/kWh which although high seems to be about right when looking at average mthly bills cost of both delivery and generation. Sure enough the costt from last august through now is estimated at around $1900. More than I expected but certainly reasonable given the miles on the car and still less than supercharging or cost of fuel in this neck of the woods!

For the last few months, I kept thinking that there was either a challenge with my system or the way Edison was seeing my usage. I guess in the end, I just need to be more sensitive to my surroundings and work with the fam on any efficiencies we can muster. Plus I get free charging at the office, perhaps I need to spend more time there and less on the road.

Great forum that I expect to spend more time on, thanks again for the thoughtful responses!

 

[jjrandorin]

NP and welcome. FWIW, even with all the above I said, I have 2 powerwalls, and I am also in NEM 1 on a tiered rate. I didnt get them to be green, I got them for less dependency on the Utility, after I went through a couple of power outages / power safety shutoff situations.

One of the most frustrating emotions I have ever felt was sitting in my home (in temecula), and having a situation where a car accident caused a 3 day power outage for a couple of blocks around me, having solar on my roof, plenty of sun, and sitting in a home with 2 fridges worth of food that slowly went bad due to no power.

That same year we had a power safety shutoff (PSPS) for most of a day or so. Didnt lose the food that time, but sitting in the house with no power, and sun out (but not generating solar because thats how they are setup when you dont have batteries / home storage), my wife and I said "we dont want to do this again").

I added 2 powerwalls to my existing solar, for resiliency, not because it was going to pay me back, or because I cared a ton about green energy, environmental concerns, etc. Those were side effects of my selfish desire to "not go without power in this house again, if we are going to be here for at least 10 more years".

I have been exceedingly happy with the purchase. I got them in 2020, and when fire season rolls around (like now), I can be sure that I will have power, at least as long as the fires dont reach my neighborhood, heh.

So, worth it? For me, absolutely yes it has been. I feel a connection to my house that I didnt quite feel before, especially as I got them installed in 2020, and we all know how 2020 - 2022 was.

Thats why its kind of hard to quantify "worth it" for these devices (home storage). Depending on your current cost for electricity, what plan you are on, and what, if any, value you put on less dependence on the utility, environmental impact, etc, they can either be worth it to you, or not. Purely from a financial aspect though, they tend to not pencil out, especially in your circumstance.

Anyway, welcome again.

 

[robbyville]

NP and welcome. FWIW, even with all the above I said, I have 2 powerwalls, and I am also in NEM 1 on a tiered rate. I didnt get them to be green, I got them for less dependency on the Utility, after I went through a couple of power outages / power safety shutoff situations.

One of the most frustrating emotions I have ever felt was sitting in my home (in temecula), and having a situation where a car accident caused a 3 day power outage for a couple of blocks around me, having solar on my roof, plenty of sun, and sitting in a home with 2 fridges worth of food that slowly went bad due to no power.

That same year we had a power safety shutoff (PSPS) for most of a day or so. Didnt lose the food that time, but sitting in the house with no power, and sun out (but not generating solar because thats how they are setup when you dont have batteries / home storage), my wife and I said "we dont want to do this again").

I added 2 powerwalls to my existing solar, for resiliency, not because it was going to pay me back, or because I cared a ton about green energy, environmental concerns, etc. Those were side effects of my selfish desire to "not go without power in this house again, if we are going to be here for at least 10 more years".

I have been exceedingly happy with the purchase. I got them in 2020, and when fire season rolls around (like now), I can be sure that I will have power, at least as long as the fires dont reach my neighborhood, heh.

So, worth it? For me, absolutely yes it has been. I feel a connection to my house that I didnt quite feel before, especially as I got them installed in 2020, and we all know how 2020 - 2022 was.

Thats why its kind of hard to quantify "worth it" for these devices (home storage). Depending on your current cost for electricity, what plan you are on, and what, if any, value you put on less dependence on the utility, environmental impact, etc, they can either be worth it to you, or not. Purely from a financial aspect though, they tend to not pencil out, especially in your circumstance.

Anyway, welcome again.

Some pretty invaluable info here thanks again (and as always)! Interesting that we're not that far away from eachother and seem to be in similar circumstances. In the 8 years I've lived in Palm Desert, I've been fortunate in only having one or two rolling black outs and I can't remember any of length. Still, I've always preached to try and control one's own circumstances where possible. And, as you mention above, there's a lot more to consider than just blackouts. I've set up a meeting with the folks at Renova to discuss potential battery storage.

 

[Miata Head]

Like someone earlier said, home charging is probably pushing you into Tier 2 or 3. The last page of you bill will show you a bar graph of your billed usage and tiers, along with each rate. You should download your usage data, then build a spreadsheet (not a simple task) so you can compare rate plans and model what works best for your usage pattern. You can also use it to change your patterns to reduce your costs. You can then also model in how much a Powerwall could save you.

I'm not in such a hot area like Temecula and I'm NEM1 on Tiered. We use A/C only when it's really hot out and set to like 78 normally. Based on our usage, I estimated my breakeven between tiered vs TOU-D-Prime is around 12k annual miles. This is probably too high though, as I'm not sure what i get back from the excess generation.

Somewhere on reddit I found a spreadsheet that you can modify to build off of.

 

[robbyville]

Well, update time... Spent some time with a sales consultant from Renova, I had also sent him a copy of my annual reconciliation bill. As suggested by your posts previously he essentially confirmed that I'm using more than I'm producing and as a result the power walls would probably not even charge up often enough or with enough capacity to actually make a dent in my bills.

His suggestion was for a new system entirely with more capacity (11.68kw with 32 panels vs. my current 8.4 estimated and 27 panels). they would also be putting all panels on my South facing section vs. current which are all on the North side. This would of course move me to a different billing program within SCE but he says that ultimately it would still be to my betterment since SCE has initiated potential rate increases for the upcoming 6 years and as a result I can see my annual costs growing. He doesn't say whether there is an option to simply add a few new, better panels to the South side and tying them into the current system, I will ask but I'm assuming different systems don't play nice together...

The lease option with battery storage came out to $306/mth (for 25 years aye caramba), with the expectation that my SCE bill would work out to roughly $55/mth and I would be generating more than I'm taking based off my reconciliation. I have not spoken to him since receiving the proposal so I do not know if that $306/mth is an "out the door, fully installed" price. If so, it would ultimately make my annualized costs about what they were this past year, so theoretically it would insulate me from additional increases and give me a new (better?) system with additional productivity. According to the inspection last week, my current system is working appropriately and is in it's 8th year since install.

The equipment he's suggesting is via SunVault 13, not sure if that's a good manufacturer or not.

I'm assuming that if I were to consider this option that my current system has absolutely no resale value?

 

[taphil]

NEM 1.0 $300/mo avg electric bill vs. NEM 3.0 $306/mo x 25 years (that's $92,000) + monthly NBC costs?

Invest in index fund, charge the car during off-peak hours, and turn up the thermostat.

 

[robbyville]

NEM 1.0 $300/mo avg electric bill vs. NEM 3.0 $306/mo x 25 years (that's $92,000) + monthly NBC costs?

Invest in index fund, charge the car during off-peak hours, and turn up the thermostat.

Yup I would tend to agree. Need to see if there are any prepayment penalties as well should I go that route.

Of course, if SCE is going to increase rates by a factor of… then my annual bills will continue to climb. But I’ve got a completely decent system as is regardless of not meeting my ultimate needs and could we adjust our way of living; probably so to a certain extent (my wife works from home and I work partially from home) so it behooves us to be comfortable.

I can’t see a change being worthwhile but I do wonder about supplementing the current system

 

[fiszix]

I added 2 powerwalls to my existing solar, for resiliency, not because it was going to pay me back, or because I cared a ton about green energy, environmental concerns, etc. Those were side effects of my selfish desire to "not go without power in this house again, if we are going to be here for at least 10 more years".

I'm resurrecting an old post, but this seems entirely on point. Like both you and OP, I'm on NEM 1.0, and I'm with SoCal Ed. I've experienced some power outages, and so I'd like to be able to add powerwalls to my home. Ideally, I'd like to integrate them with my existing grid-tied system, without losing NEM 1.0.

The Tesla Powerwall site says that adding a powerwall 3 to a system forces you into NEM 3.0, and I think the reason why is that even just one powerwall 3 is more than 10kWhrs of capacity. At least under PG&E, that doesn't seem to fall within their form allowing some addition of storage to an existing NEM 1.0 system (though I may be wrong).

Is there still a way to add some powerwall to an existing NEM 1.0 system without being forced to NEM 3.0?

If not, then I think I'll have to consider an off-grid system... and I'd probably set that system up to be able to charge my i3 (daily commuter), and somehow figure out a physical blocking interconnect that would allow the off-grid system to power some essential house loads if the grid went down, but only while the grid was down.

I mention the off grid possibility also as an option for the OP. if, with your NEM 1.0 system, you are still paying $4k+/year, then it may make sense to create an off-grid system designed to offload some of that $4k/year from your grid tied system, and somehow design it so that you could use it to power the rest of your house when the whole grid is down. i could see the off-grid system as dedicated to car charging or some specific significant loads that can be physically segregated from the normal house loads (i'm thinking appliances).

 

[fiszix]

OP - i was searching around and found this, which seems legitimate, and would likely be an option for you:

 

[Ampster]

i was searching around and found this, which seems legitimate

If you look carefully at the wording in the NEM agreements for PG&E and SCE there is some language that describes a parallel system and limits your ability to install a parallel system. I have a permitted SolArk system similar to the one pictured in the video and configured for no export beyond the 1 kW allowed in my NEM agreement. By a strict definition it is running in parallel and the narrator in the video also used the term, "parallel". Worse case my opinion is this could be a breach of contract with my power company and I am willing to take that risk. I am almost self sufficient so the downside risk of being kicked out of my existing NEM 2.0 and being forced into NEM 3.0 is worth the upside benefit of being able to use batteries and additional solar to avoid peak period charges and have a backup. You mileage may vary depending on your own risk aversion profile.