-
Want to remove ads? Register an account and login to see fewer ads, and become a Supporting Member to remove almost all ads.
Should I get 1, or 2 powerwalls for my existing PV system?
- Thread starter Jeff Hudson
- Start date
What's your definition of optimal? I know that you hate it, but that really is the question. Do you want to optimize your costs? Your grid reliance? Your backup capabilities? Do you want to reduce your upfront costs?
Resaleing power is pretty much a normal thing. $0.11/kWh in the summer is relatively low.
During the summer, before I had solar, I would hit 800-1000kWh so you can imagine the $$/cost and this is setting the thermostat over 80. There are news stories of people paying much more of course.
Here's our pricing plans now:
This is from last year:
I try to keep usage below/around 20kWh per day and I totally micromanage stuff, but with solar/batteries, generally don't have to. As you can see, you really need to avoid peak cost and it's funny to me when I see folks complaining about their $0.11/kWh.
At least ROI is pretty high for solar here as you can imagine, not so much under NEM3.0 and probably less with new income based monthly charges though.
Thanks. So the AVERAGE rate in S.D. is 36¢/kWh, still 3¢ higher than Hawai'i, but better than 83¢.
I love baked potatoes. For years I always nuked them because I didn't want to waste energy heating the entire oven for one potato. Now that I have solar, I bake my potato in the oven, and I let the A/C keep the house cool, and it's all free and zero-carbon.
Solar is a no-brainer here, and it sounds like San Diego is probably similar.
A note on net-metering and other utility buy-back systems: Economically it can be good: You sell them your excess during the day, and buy back power from them at night, and depending on the system and your climate, you can come out ahead or at least have free energy. My concern with this system is that I don't care about cost. I want to be carbon-zero. I cannot eliminate carbon from my life, but at least for my home and car energy I can. But not if I'm buying fossil-fuel power at night. My Powerwalls (which I got because I could not get net-metering) allow me to be zero-carbon for my energy needs. Now what I really want is to be able to send the utility my excess energy. But they won't take it. I believe they're over-subscribed and already getting all the daytime energy they can use. They need grid storage capacity because a LOT of people here have excess solar generating capacity.
I love baked potatoes. For years I always nuked them because I didn't want to waste energy heating the entire oven for one potato. Now that I have solar, I bake my potato in the oven, and I let the A/C keep the house cool, and it's all free and zero-carbon.
Solar is a no-brainer here, and it sounds like San Diego is probably similar.
A note on net-metering and other utility buy-back systems: Economically it can be good: You sell them your excess during the day, and buy back power from them at night, and depending on the system and your climate, you can come out ahead or at least have free energy. My concern with this system is that I don't care about cost. I want to be carbon-zero. I cannot eliminate carbon from my life, but at least for my home and car energy I can. But not if I'm buying fossil-fuel power at night. My Powerwalls (which I got because I could not get net-metering) allow me to be zero-carbon for my energy needs. Now what I really want is to be able to send the utility my excess energy. But they won't take it. I believe they're over-subscribed and already getting all the daytime energy they can use. They need grid storage capacity because a LOT of people here have excess solar generating capacity.
I really don't think that's true anymore. If you look at the chart, SDG&E can say the average is $0.36/kWh in very old news article, but does anyone really use that much power from 12am - 6am? Before I got solar, I tracked and looked up old bills and noticed I used about 75% of my energy from 5pm - 10pm.
TOU-DR1 is costing us:
Off Peak from 6am - 4pm is $0.403 - $0.520 when folks are normally at work, they come home and it's $0.716 - $0.833. 12am - 6am is $0.238 - $0.355. That news story has old prices I think and don't think anyone is paying $0.36/kWh anymore (and wasn't before neither).
Yes, Hawaii has too much solar and can't use anymore during generation hours and why they don't have 1:1 net metering anymore. We know folks in Hawaii who got solar with all the state credits and net metering and their costs were insanely cheap back then. Like 1/3 or something crazy of the cost with all the tax credits. A total no brainer.
Thanks for the additional correction. Sounds like SDG&E is gouging customers for its own incompetence in allowing its infrastructure to degrade to the point of being a fire hazard. At least Hawai'i's utilities have an excuse: They have to ship diesel fuel 2,500 miles. Though here on Maui we're getting about half our electricity from wind and customers' rooftop solar, and they're planning to increase that.
Thanks for the reply Daniel. Just to clarify my situation, I provide 100% of my Solar PV energy output exclusively to my utility company because it is wired to a separate generation meter and then to my grid-tied utility meter. I am reimbursed for all (100%) of it at a constantly (monthly) adjusting rate. I'm not sure if this is the same as what I think is known as Net Metering but the term seems an accurate enough description for my understanding, although I think the Net Metering term most likely applies strictly to a bi-directional single meter installation. Then, on the other hand, I am charged the same identical rate for any electricity I consume. This is the purpose of having two meters (Consumption [Original Meter] and Generation [New Additional Meter]). Other electricity utility providers have a plethora of differing billing schemes as we've all come to learn.
Even though I've already mentioned that my electricity utility provider does not generate the electricity it sells to me I think it is important to add that because of my Solar PV system I have an associated contract with the actual electricity generator (TVA). As part of that contract TVA will reimburse me $0.02/kWh for 100% of what I generate. This separate payment is a premium enticement to participate in their Green Power Provider program. The two contracts run for a period of 10 years which ends December 2025. Unfortunately, at the present time, TVA has preemptively expressed they will not renew this consumer/commercial GPP program. It was a little cumbersome the way they ran it (mailed monthly paper cheques) but it did provide the incentive that caused me to purchase my Solar PV system so there's that. There was also a $1,000 payment upon my successfully completing the commissioning requirements prior to operating which was nice. I mentioned this aspect of my electricity arrangement just to provide more information as to how different everyone's situation could be. Just as a side note and to be more informative I think it is revealing how important renewable energy is to those that claim to generate it. TVA's contract states:
"For the term of this Participation Agreement, the Participant and Qualifying System Owner must not make claims or statements about using renewable electricity, cutting back on greenhouse gas (GHG) emissions from electricity through the use of renewable electricity, or receiving any other environmental benefits of renewable energy use which would constitute the claiming of a renewable energy credit (REC). Participant and Qualifying System Owner understand that any such claims violate the terms of this Participation Agreement, since TVA, through this Participation Agreement, is purchasing one hundred percent (100%) of the RECs generated by the renewable energy installation and selling the RECs through its Green Power Switch program."
So after perusing my contracts again I think I've learned if I choose to install a Powerwall my utility provider might choose to uninstall the generation meter (I need clarity on this point) and I would exit both contractual agreements. At that time I would be able to claim the renewable power generation credit even though the claim would only be words.
All that said, is there any connection configuration that allows the Tesla Powerwall equipment to send excess generated electricity to my generation meter? This is the technical question I need answered although I need to get answers from my utility provider and installer which I will endeavor to do. I need to get on this and quit procrastinating which I have become an expert at with age.
You could, but if connected that way, you would lose at 10% of your power due to charge/discharge losses, and you would have no home backup in case of an outage. Unless there is at least a 10% boost in your reimbursement rate for generation at certain times of the day, and you don't want power backup in outages, I can't think why you would want to set it up that way.
All the best,
BG
You have to think of your setup as three entities. You are the consumer, using things that your meter counts. (i.e. everything downstream) You buy power from two entities, one TVA, and the other, yourself. Your solar system seems to be a provider just like TVA is and should be treated and considered as one.
With that said, there isn't anything that your solar system can do to help you inside the house. In reality, just ignore that it is there and treat it just as another source of income.
It sounds as if in the future, you will have to disconnect you solar from the grid and if you want to continue to use it, then an electrician will need to connect it to the other side of your meter.
But to answer your question, no. Aren 't they already buying all the power that you generate?
If you were referring to me you should know I was not complaining. Also, learning about the cost of electricity in other areas and the surrounding circumstances is revealing as to how good I have it here where I live.
I'm beginning to lean towards this thinking mainly because I have no interest (no incentive) in energy arbitrage and I do not like being tied to a contract if and when I choose to sell my house.
Thanks to everyone for their input. I think I know what I want to do now which is to hear what the installer recommends with respect to exiting the two contracts and installing Tesla Powerwall(s). I now have a good understanding where my hang-up was with this decision.
Jeff: Thanks for the further clarification. As I understand net metering it basically amounts to what you have, for all practical purposes: You get paid the same rate for what you provide as you pay for what you consume. Except that, as you note, I think it's usually done on a kWh basis, rather than the weird way they do it with you. Other schemes pay less for energy you provide to them than they charge you for energy you get from them.
I can't help you with the question at the end of your post because I know nothing about the technical aspects. Al I know is that on my system I'm allowed to send electricity to the utility only in "small" amounts for load balancing, and they don't pay me for that. I pay a minimum amount to be connected, and that covers the first 40-ish kWh per month. If I draw more than that my bill will go above the minimum. Which in my case has never happened. My installer set it all up to conform to the requirements. Also, my system provides power to my whole house during grid outages. The transition is seamless and I don't even notice it.
My system would be able to supply excess power to the utility if the utility permitted that. My installer would merely have to change some settings, which he might even be able to do remotely. Not sure about that.
Sounds like TVA wants to be able to claim the green generation credits, since they have such a (well-deserved) bad reputation for burning coal. But I cannot imagine why they pay you with a paper check rather than direct deposit. I also cannot imagine why your utility would stop taking your electricity, though they'll probably pay you less for it when the contract ends, just because they can.
I can't help you with the question at the end of your post because I know nothing about the technical aspects. Al I know is that on my system I'm allowed to send electricity to the utility only in "small" amounts for load balancing, and they don't pay me for that. I pay a minimum amount to be connected, and that covers the first 40-ish kWh per month. If I draw more than that my bill will go above the minimum. Which in my case has never happened. My installer set it all up to conform to the requirements. Also, my system provides power to my whole house during grid outages. The transition is seamless and I don't even notice it.
My system would be able to supply excess power to the utility if the utility permitted that. My installer would merely have to change some settings, which he might even be able to do remotely. Not sure about that.
Sounds like TVA wants to be able to claim the green generation credits, since they have such a (well-deserved) bad reputation for burning coal. But I cannot imagine why they pay you with a paper check rather than direct deposit. I also cannot imagine why your utility would stop taking your electricity, though they'll probably pay you less for it when the contract ends, just because they can.
If you are hooked to a grid, you may be financially neutral, but will usually not be Carbon Neutral. Your home runs on the power line, but shunts your excess power consumption back into the grid. Base power will still come from their generating plants.
A solution for many will be to simply wait until your EV becomes bi-directional. Will not need the costs and complexity of PowerWalls as your EV will use it's much larger battery to power consumption during peak demand/expense hours.
A solution for many will be to simply wait until your EV becomes bi-directional. Will not need the costs and complexity of PowerWalls as your EV will use it's much larger battery to power consumption during peak demand/expense hours.
Lol, yeah right? Don't think I didn't ask but this is the only way they do it. It gets even more odd in that there is a 3 month delay such that I windup cashing a cheque 3 months after their system records my generation - lol.
Also, to clarify, my utility company does reimburse me per kWh on the same billing cycle and not some other way.
Thanks for taking the time to help me understand how my situation would change if I decide to have Powerwall's installed.
That's not how my system works. It draws an insignificant amount of power from the grid, and sends an insignificant amount of power to the grid, for load balancing only. The meter shows energy from the grid and energy to the grid, and as noted, it's insignificant.
I'm not on any sort of net metering or partial net metering. I pay the utility for any and all energy I get from the grid, and am not paid or compensated in any way for energy I send to the grid. In actual practice, I draw so little from the grid that I never pay more than the monthly minimum.
Also, the Tesla app shows current flow in real time, and there's almost none coming in from the grid. When the grid is out, my home functions seamlessly the same as ever. The only exception was one time (in almost five years) that we had three or four days of heavy overcast and a lot of rain. My Powerwalls ran out overnight on (IIRC) the third night, and the house ran on grid power until the sun came up and was producing enough that the grid power was no longer needed.
With the old A/C, I had to draw a little current from the grid to start up the compressor. So I had to be on the grid and the A/C would not start during an outage, though if it was running it would keep running. But the new A/C can start without any assist from the grid. The only reason I pay the monthly minimum now is to have power if there's an extended storm that blocks the sun for more than a couple of days.
When I lived in rural North Dakota I was on Cass County Electric Co-op. Technically it was customer-owned, but in fact it was run by a bunch of old farts who pandered to the coal industry, and the profits went to them as salary. Every month, all the customers received "credits" denominated in dollars, proportional to their electric usage, basically a tiny cash-back percentage of their bill. Except that those credits were paid out 20 years later. Without interest. You had to declare the credits as income in the year earned, but you only got the money 20 years later, after inflation had cut the value of those dollars about in half. I got checks for, I don't remember, $15 or $20 every year, for 20 years after I left there.
Well that's a pretty weird customer experience. It sure has my 3-month reimbursement delay beat.
It was a scam from the get-go. On the plus side, rural electric co-ops got electricity to areas that commercial utilities were not willing to serve. On the minus side, it was government money that was used to set them up, but in a way that shafted the consumers as badly as if it had been private companies. The company issued "dividends" in the form of "capital credits" which were "income" according to the IRS, but then the company kept that money as zero-interest "loans" from the customers, for those 20 years.
Similar threads
- Question