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Are powerwalls a necessity for SoCal residents?
- Thread starter Carbonfiber
- Start date
are you dissing El Dorado County wines
Yeah - wines are a lot better there. Also, Healdsburg has some great restaurants. We prefer Sonoma over Napa. In Sonoma they have a saying: Sonoma has good wine; Napa has auto parts.
SoCal Dave
Member
Most businesses would thank you for being one of their best customers!
SCE TOU differences for summer rates below (its not a 5 cent difference under any plan).
Purchasing solar will FORCE a TOU rate, if not already one one... one of these below. TOU prime is the "EV" rate.
The short answer to the OP is, with an 8.X sized solar, you likely want 2 powerwalls, not one, if the goal is to not use energy during "peak" time. OP may not even be on a TOU rate now, because many people are still on domestic, which is the old tiered rates where "the more you use, the more it costs" but WHEN you use it doesnt really matter.
In my case, I am holding onto my domestic rate because under NEM 1.0 I do get compensated 1:1 for solar, AND the rate I get compensated for solar at is the "tier 1" energy rate, regardless of when I use it, but with my powerwalls I can use very little power from the grid if I dont use AC.
That is a serious differential, which drives the "cost" of powerwalls way down. At the moment, LADWP is not that extreme.
But its a good illustration of where things may be headed and why powerwalls may become more and more cost effective.
Defending yourself against a 15 cent pew kwh rate differential is worth about $75 bucks a month. Two powerwalls, after tax credit, financed through Tesla's one click Mosaic loan, costs about $79 bucks a month over 20 years.
SoCal Dave
Member
However, Powerwalls are not the only way to solve TOU. Overproduction can also solve it. It is cheaper to build a larger system (if one has the space) than to buy Powerwalls.
Take yesterday for me as an example. I had to buy power at On-peak prices. However, because I overproduced so much during the day I more than offset that price increase.
I ended up with a net credit for the day of $1.75. I did have NBCs which PowerWalls could have helped eliminate, but it was only $0.52 for the day.
Take yesterday for me as an example. I had to buy power at On-peak prices. However, because I overproduced so much during the day I more than offset that price increase.
I ended up with a net credit for the day of $1.75. I did have NBCs which PowerWalls could have helped eliminate, but it was only $0.52 for the day.
SoCal Dave
Member
As I stated in the other thread, you don't want to over produce for the year. I suspect you aren't, but over production on a specific day doesn't necessarily mean over production on an annual basis. Like my system, you are probably "banking" these over production credits in the summer, but charge against them in the winter
I came across this chart on the internet and not sure how accurate it is, but Tesla Advisor said the medium size system should give me anywhere from 31-44 kWh, not 20-30 kWh. He said this chart was for a region that had less sun light exposure. Can someone please share if their system is more align with this chart or Tesla advisor?
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SoCal Dave
Member
Actually, I want to overproduce as I'm on NEM 2.0. What I don't want is a net credit at the end of the year. The overproduction helps ensure I offset the TOU and end up with as close to a $0 bill as possible.
Probably depends on the Rate Plans. I'll check my last True Up. If I recall correctly, my NEM charges were ~$100., but I on a kWh basis I used quite a bit more than I produced.
not sure where you got that chart, but any online chart you dig up will need to account for your specific area. Your best bet is to go to PVWatts website and put in your address and model it;
Failing that, for southern california in most places, that chart would be a WINTER chart, not a summer one (so your advisor is more right than that chart).
You may be thinking that your system will generate "31-44 a day" all year round, and that is absolutely positively NOT the case, and even teslas information somewhere will tell you that. During the summer you will produce a lot more, and during the winter you will produce a lot less.
Now, with that out of the way, to somewhat answer the question based on my own system (which is 8.7kW), I produce between 11,900 and 13,000 kWhs of energy every year. During june and july, my average daily production is somewhere between 45 and 55 kWhs. This same system, in december, produces between 20-27 kWhs.
Thats why I said the chart would be accurate if you were talking about November - february production, and waay out of line for march - october production. Unless you have a lot of shading, your 8.1X system will likely produce around 11,000 kWhs for the year, and right now would likely be producing between 30-40kWhs.
PG&E requires extra paperwork to complete if you create a PV system that is oversized based on your historical use. There are people on this forum that have been denied for oversizing their systems too.
And there's a pretty complicated form in the SGIP paperwork if you oversize and still want to get Powerwalls for the benefits of the battery backup.
PS: I'm in the process of Over-sizing my PV AND I'm Over-Powerwalling because I'm trying to make sure I pay those PG&E jerks as little as possible. This will probably all come back to harm me in the end in a Moby Dick sort of way. Like I'll get killed by a angry, runaway PG&E truck or something.
PPS: PG&E sucks.
This is my total electricity usage, yesterday... hourly. You can see that, yesterday, I had zero usage for the entire day from SCE. Powerwalls ran my home from midnight to sun up, solar ran home and charged powerwalls during the day, then powerwall took over and ran the home the rest of the day.
The reason that the negative kWhs dont show up till after 12 noon, is because the solar was running my home and also filling my powerwalls. Powerwalls got full, then feed to SCE started.
I use self powered, because I am not on a TOU plan, but, @holeydonut maybe something to look forward to.
The reason that the negative kWhs dont show up till after 12 noon, is because the solar was running my home and also filling my powerwalls. Powerwalls got full, then feed to SCE started.
I use self powered, because I am not on a TOU plan, but, @holeydonut maybe something to look forward to.
SoCal Dave
Member
SCE approved this for me
Teasing aside, my need met wasn't as high as in the original quote. The yearly production is now estimated at 2MWh less. 18MWh instead of 20MWh.
SoCal Dave
Member
Do you even need to be grid connected? Or could you tell SCE to disconnect you?
Uncle Paul
Well-Known Member
Just don't pay your bill and SCE will disconnect you. (but maybe not right now with Covid not allowing them to disconnect)
Uncle Paul
Well-Known Member
Oh I need to be grid connected. I think we live in the same area, and its been "reasonable" out here in temecula but its about to get hot again.. really hot.
My self powered score since january is around 85% (when I had the powerwalls installed). If I dont use AC, I am in good shape, but during the hottest days the quietcool attic fan I installed doesnt help because it doesnt cool off enough at night.
Regular days (high up to 90 or so), it cools down out here in the evening and my quietcool fan brings in enough cool air from outside that I dont need to turn on AC. I dont have a pool, most of my power usage is my computer(s), 2 fridges., and a pretty high end AV system for TV and movies.
EDIT:.. A typical day of usage in my home is 26-32 kWhs, provided i dont need to charge my car. My car took me from being an annual net producer to net consumer, since I normally commute to North County San Diego daily. Of course, with Covid, not driving much now, so a lot less EV charging.
My trip to Oceanside and back uses almost the same energy it takes to run my home for 24 hours (25 ish kWhs lol).
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