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PowerWall Without Solar?

HankLloydRight

No Roads
Jan 18, 2014
12,899
10,910
Connecticut
somebody else in CT mentioned that has the program to discharge batteries during peak times to manage the load, but that program seems to be a very defined one in that it happens automatically based on specific criteria.

That's the ConnectedSolutions program. ConnectedSolutions | Tesla

And only offered by Eversource that covers 90% of CT.

My utility is United Illuminating which covers the rest of CT does not offer CS.

Where I moved from was in the Eversource service area, but since I didn't have solar, it didn't make much sense to join the program:

Powerwall systems not paired with solar generation will not be allowed to export power to the grid, but will still be able to discharge to serve home load. This limitation will greatly reduce the earning potential, but if the home load during events averages 1kW, Powerwall can still earn as much as $200 a year in MA and CT, and $290 a year in RI.
 

wjgjr

Active Member
May 11, 2020
1,168
912
Silver Spring, MD
The question is, how much is it costing the utility to make the widgets and how much profit are they making on it? It you think purely in terms of load shifting, you are asking to buy the widget at 10 cents at 3AM when it’s cheaper to make the widget so the utility makes their 3 cent profit. Then you are going to not buy the same widget at 3PM when it costs 40 cents. But it costs more to make the widgets at 3PM, so the utility would have only made the same 3 cents on that widget anyway. You’re still buying one widget and the utility is still making their 3 cents, it’s just a matter of buying the widget when it is cheapest.

I can see how the utility would be against arbitrage, but just load shifting isn’t so bad for the utility.

I agree with what you are saying and would take it a bit further. In a sense, this is like a company that has two options for making widgets - option 1 is to make them at a steady rate and warehouse them until they are needed. Option 2 is to make them only needed. Typically, option 2 is more expensive - in normal manufacturing, you would have to rush in more employees, have more assembly lines available, etc. And, for power, this is also true - particularly the need for more power plants.

Option 1 is what we are talking about here. Essentially, the utility is paying us to store the widgets until they need them later - the batteries are essentially a warehouse for storing power. And, for providing that service, we should be paid, just as a warehouse is paid for storing the physical widgets until they are sent to the customer or store. This all does assume that by flattening the daily power curve, the utility will save money overall (and/or be better for the environment, assuming the public will pay for that benefit in some way.)

And, of course, utilities may really prefer to warehouse their own power, and we have seen large battery farm installations, so it will be interesting to see how regulators approach the balance between home-scale and utility-scale battery installations.
 

getakey

Active Member
Jan 28, 2020
1,130
368
95762
Here is an interesting site for part of the grid in CA which includes PG&E. You can change the date in the graph to see past days
The second graph shows "Net Demand" which they define as demand not including renewables. You can see how the Peak demand jumps as the sun goes down. A lot of that demand is met by buying power from other Western States. There is a Capacity Tab where you can see this. Note that about 10% of the capacity is supplied by Diablo Canyon nuke plant which runs 24/7. Rather than extending the life of the plant (like most other States are doing) they are going to decommission the plant in 2 years at a cost of $4Billion. What will replace this power is unclear

California ISO - Today's Outlook
 

gpez

Member
Apr 25, 2019
657
535
USA
Here is an interesting site for part of the grid in CA which includes PG&E. You can change the date in the graph to see past days
The second graph shows "Net Demand" which they define as demand not including renewables. You can see how the Peak demand jumps as the sun goes down. A lot of that demand is met by buying power from other Western States. There is a Capacity Tab where you can see this. Note that about 10% of the capacity is supplied by Diablo Canyon nuke plant which runs 24/7. Rather than extending the life of the plant (like most other States are doing) they are going to decommission the plant in 2 years at a cost of $4Billion. What will replace this power is unclear

California ISO - Today's Outlook

Probably should just start a new thread but it's exactly this sort of crummy planning that convinced me to go solar + Powerwall. Being substantially less reliant on bureaucrats with questionable planning skills and likely ulterior motives is huge for me...

We're not immune here in WA state either. Hydro is big but finite. Increasing EVs will continue to tax the grid and unless our neighbors (cough CA cough) get their supply act together there's not much headroom.
 

getakey

Active Member
Jan 28, 2020
1,130
368
95762
Probably should just start a new thread but it's exactly this sort of crummy planning that convinced me to go solar + Powerwall. Being substantially less reliant on bureaucrats with questionable planning skills and likely ulterior motives is huge for me...

We're not immune here in WA state either. Hydro is big but finite. Increasing EVs will continue to tax the grid and unless our neighbors (cough CA cough) get their supply act together there's not much headroom.

Totally agree. PG&E and CA legislature created this mess. After being part of the PSPS blackouts last year I got PWs.
 

holeydonut

Supporting Member
Jun 27, 2020
1,286
772
East Bay NorCal
Here is an interesting site for part of the grid in CA which includes PG&E. You can change the date in the graph to see past days
The second graph shows "Net Demand" which they define as demand not including renewables. You can see how the Peak demand jumps as the sun goes down. A lot of that demand is met by buying power from other Western States. There is a Capacity Tab where you can see this. Note that about 10% of the capacity is supplied by Diablo Canyon nuke plant which runs 24/7. Rather than extending the life of the plant (like most other States are doing) they are going to decommission the plant in 2 years at a cost of $4Billion. What will replace this power is unclear

California ISO - Today's Outlook


I'm curious - is there a reason the USA (and most of Western Europe) soured on nuclear power plants? I understand Chernobyl and Three Mile Island were large/bad events, but almost all major innovation has some sort of devastation associated with it; and there's usually an effort to overcome instead of just abandoning things.

China, India, and Russia seem to be building newer/better reactors, but the EU and USA are just slowly shutting them down.

For example, Lithium and Nickel mining to supply raw material for fancy batteries had laid waste with many strip mines devastating local ecology and poisoning of waterways. But regulation and enhancements have made such mining better than what we saw a few years ago. It's not like folks have just abandoned the mining of these materials.

And for the Solar cell industry; it took a few mega-collapses of the likes of Solyndra and Hanergy for that industry to clean itself up a bit and emerge better on the other side. We didn't see the abandonment of this and a resurgence of a quest to obtain "clean coal".
 

getakey

Active Member
Jan 28, 2020
1,130
368
95762
There's a new effort in USA and Europe to build small nuclear plants. I look to see some of those coming online in the near term, but doubt if CA will allow. Smaller makes a lot more sense. The smallest of them are built in a "factory" and transported to a site. The biggest argument against Nuclear (besides those events and don't forget Fukushima) is spent fuel storage.
 
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MorrisonHiker

S 100D 2021.4.15
Mar 8, 2015
9,582
8,792
Colorado
Apparently in California they have three rates... Peak, Partial Peak, and Off Peak. I haven’t seen that rate structure used anywhere other than CA though.
XCEL in Colorado has three rates on weekdays and two rates on weekends. Instead of partial peak, they refer to it as "shoulder".

They are going to be installing smart meters for everyone and implementing ToU for all residential customers in the coming years. However, they will also removing the peak period during winter months. I wish they would keep things as they are as I earn a lot more credits when there is a peak period year-round.
 

swedge

Member
May 12, 2020
67
53
Oakland, CA
"hey utility, I want to buy this widget from you at 10 cents in the middle of the night, hold onto it for 15 hours, then sell this same widget back to you for 40 cents at 4pm, and I want to buy the widgets in bulk. You are ok with that, right?"

In effect, people wanting to charge the powerwall from the grid during a cheap / off peak rate, then either discharge the powerwall into the utility at peak rates (effectively selling it to the utility for more than they bought it) or selling their solar power to the utility at peak rates while they use the cheap power "they bought from the utility", doesnt make much sense financially.
jj,

The widget analogy is not exactly accurate. The issue for the utility is that their electron-widgets are perishable, with a shelf life of essentially zero. This means that they have to have a factory big enough to make them fast enough to supply instantaneous peak demand. For us it is the price of the widgets, for the utility the issue is the price of the factory. By keeping some widgets in stock, we can reduce the size of the factory the utility needs. It is a win/win, moderated by the peak/off peak price differential.

A PW will not export stored power to the grid, and utilities wil not let us export more than our solar can produce. (In fact PG&E calculates how much my solar could produce in each month based on my system specs, and limits the credit accordingly.) The net effect is that I only sell them power I generate, and time shift power I buy from them.

I don't think we need to worry about what is fair for the utilities - they have plenty of influence over the PUC regulators.

It is true that if everyone went solar + battery to go off grid, utilities would loose their customers. As customers leave, the stranded capital will drive up utilities costs per kWh and hence prices, which will accelerate the shift to solar. Creative destruction, I think the economists call it. But along the way, folks in high rises or rentals or unable to invest in off-grid solutions will all be in trouble. Net Metering is an interesting middle ground because it lets solar be sized for average production rather than large enough to cover short, cloudy winter days. The trade off here is it keeps some revenue coming in from solar customers and softens the blow of stranded capacity. But all this is what every industry gets to deal with as technologies and societies change over time. Seen any carbon paper lately? Photgraphic film? Vacuum tubes?

SW
 
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jjrandorin

Moderator, Model 3, Tesla Energy Forums
Nov 28, 2018
8,215
9,062
Riverside Co. CA
jj,

The widget analogy is not exactly accurate. The issue for the utility is that their electron-widgets are perishable, with a shelf life of essentially zero. This means that they have to have a factory big enough to make them fast enough to supply instantaneous peak demand. For us it is the price of the widgets, for the utility the issue is the price of the factory. By keeping some widgets in stock, we can reduce the size of the factory the utility needs. It is a win/win, moderated by the peak/off peak price differential.

A PW will not export stored power to the grid, and utilities wil not let us export more than our solar can produce. (In fact PG&E calculates how much my solar could produce in each month based on my system specs, and limits the credit accordingly.) The net effect is that I only sell them power I generate, and time shift power I buy from them.

I don't think we need to worry about what is fair for the utilities - they have plenty of influence over the PUC regulators.

It is true that if everyone went solar + battery to go off grid, utilities would loose their customers. As customers leave, the stranded capital will drive up utilities costs per kWh and hence prices, which will accelerate the shift to solar. Creative destruction, I think the economists call it. But along the way, folks in high rises or rentals or unable to invest in off-grid solutions will all be in trouble. Net Metering is an interesting middle ground because it lets solar be sized for average production rather than large enough to cover short, cloudy winter days. The trade off here is it keeps some revenue coming in from solar customers and softens the blow of stranded capacity. But all this is what every industry gets to deal with as technologies and societies change over time. Seen any carbon paper lately? Photgraphic film? Vacuum tubes?

SW

Good analogy on the time sensitivity of the widgets. In other countries however, its my understanding they CAN export powerwall power to the grid (or charge from the grid and sell all solar power during peak time, which is very similar).

In any case, its interesting to me where this ends up, just like @wjgjr said earlier.
 

swedge

Member
May 12, 2020
67
53
Oakland, CA
I'll definitely pursue the letter from the power company avenue. Thank you.

350.png
Hank,

Bingo! From jj's comment, and with help from member cwied, in this thread:

member Fonzi03 describes the process and has screen shots of his Az system charging from both solar and grid simultaneously.

This is very, interesting. We suspected the PW could do this, but the question was wether Tesla could allow us to do it or not. At least in Fonzi03's case, it appears they did. Apparently Tesla responded to his installer, and required both a letter from the utility and assurance that federal income tax credit would not be claimed, plus much cajoling and patient persistence.

So, no guarantees, but what appears should be possible, may actually be possible.

SW
 

HankLloydRight

No Roads
Jan 18, 2014
12,899
10,910
Connecticut
That's a great thread, thanks for finding it!

I hope I have an easier time because I won't have had any costs for either of my Powerwalls, so right from the start, I won't be able to take the ITC for them, and only claim the ITC for the solar install. The last step is getting my utility to agree to grid charging. I'll fight that battle once I get the system installed.
 

Ribeyesteak

Member
Dec 16, 2020
72
63
California
Question, I am about to install solar at my house but after reading the stupid rule from Tesla concerning powerwalls not being able to charge from the grid in southern California, I am wondering this:

Can I install PW before solar (without any SGIP or ITC rebate) so it's setup with the capability to charge from the grid and then have my solar installed after (and not connect the PW to the solar)? This may be the only workaround for being able to charge PW from the grid, engage in usage manipulation and maximize financial perks. If this was possible, would it mean that my PW could never be charged from my solar setup?

Thanks.
 

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