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What hours should I run my Powerwalls

gyaayg

New Member
May 21, 2021
2
0
Silicon Valley
On just one PW, good luck.

:rolleyes:That's real helpful... I didn't say I want to be completely off the grid - did I? All I want to do is maximize the $ benefit. I can do that with 1 PW2.


Depending on how "recent" your install is, the algorithm might not have learned your usage profile well enough to do the projections.

Advanced mode has two options: Balanced and Cost Savings.

According to Tesla's descriptions of the two modes, Balanced will give you the higher self powered rating.
That is what I use. I would recommend leaving it on Balanced for at least two weeks and then reporting back to us.

I've had the system active since Christmas 2020. I'll try the Balanced setting and let you know; Thx for this tip. Just fyi - last night, I used the 'Self-Powered' option - and the single PW2, lasted fine from sunset to sunrise the next day, for me (and the PW2 ended up at about 40% capacity, by the sunrise). No power used from the grid at all.

I recognize I got lucky, we are approaching peak summer; And as fall/winter sets in, the dynamics will be different. Also, if on super-hot days in summer, I end up using the central-AC at night - it's going to take power from the grid.


No. There are two different measurements going on. One is measuring the value of energy when you give it to the grid in $. The other is the total amount of kWh that you produce vs use during your yearly (prior to true up) period. This is where NBCs and other factors are considered.

So you not only have to consider the time value of the energy you use and provide, but you need to be aware of how your total energy usage affects how much you pay too.

And it can get even more complicated if you are on a rate plan that is tiered but I have little understanding of how those work with solar and they are going away anyway. And you are on the TOU plan.

Thank you - the system does seem a bit opaque for average consumers to try and maximize. Multiple factors at play - and as many of you have said before, there's no single answer that fits all.

Also - I have only had a single scheduled power black-out - in the last 5 years that I've owned my house. So I'm comfortable keeping my reserve capacity at just 35%. And therefore, my primary objective is $. :)
 

Redhill_qik

Member
Aug 16, 2020
313
222
South SF Bay, California
Why? My batteries are charged 100% by noon, so solar is used by the house, and the left over gets send back to the grid. Batteries are in standby until 3pm when they do 100% of the house load and 100% of solar goes back to PGE
Why? Because I want to minimize the import from the grid when solar is generating.

If the house load in the morning is 1 kWh / hour from 7:00-12:00pm. That is 5 kWh that are being imported from the grid with NBCs. Splitting the PV generation between the house and the PW recharge makes more sense to me.
 
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aesculus

Still Trying to Figure This All Out
May 31, 2015
4,517
2,570
Northern California
Thank you - the system does seem a bit opaque for average consumers to try and maximize. Multiple factors at play - and as many of you have said before, there's no single answer that fits all.
And then there is what rate play fits the best, until they figure that out and either remove it or drastically change the parameters.

And now a number of parties want to retroactively change all the rules. This will totally suck since the premise was for what a 20 year payback would be. And it's not just the IOUs pushing a lot of this. Lobbyists, special interests, legislatures are all piling on.
 

MJ_CA_2019

Member
Aug 19, 2020
159
43
Central CA
Why? Because I want to minimize the import from the grid when solar is generating.

If the house load in the morning is 1 kWh / hour from 7:00-12:00pm. That is 5 kWh that are being imported from the grid with NBCs. Splitting the PV generation between the house and the PW recharge makes more sense to me.
The #1 goal of Advanced mode is to make sure you don't draw from the grid during the times you defined as Peak.
If the system thinks your batteries will be full / have enough kWh to make it through the upcoming peak time, then the system will behave as you are suggesting. If you won't make it to peak with full or enough to get through peak, then you WANT the grid to be powering your home and 100% of your PV to be charging your batteries. From my experience, the algorithm is fairly conservative. That is better than making you draw from the grid at peak time.

There isn't a way that I am aware of to force the system to store 100% of the PV during off peak and also export 100% of the PV during peak.
Self Powered ignores Time of Use and both of the flavors of Advanced have algorithms behind them that you can't manipulate.

I've read that some people setup their off peak, shoulder, and peak times to not match their actual TOU times because they are trying to game the behavior.
I don't subscribe to that philosophy. I have mine set to Balanced, matching off peak and peak times (TOU-B doesn't have shoulder / partial peak) and 15% reserve. I'm quite happy with the behavior. There isn't a way to make it better without A) installing more PV or B) decreasing home kWh usage.

P.S. I also used to be very focused on the NBCs. I now don't care because I feel that Advanced mode has the priorities correct.
 
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Kodemonkey

Member
Oct 15, 2020
134
51
Los Angeles
The #1 goal of Advanced mode is to make sure you don't draw from the grid during the times you defined as Peak.
If the system thinks your batteries will be full / have enough kWh to make it through the upcoming peak time, then the system will behave as you are suggesting. If you won't make it to peak with full or enough to get through peak, then you WANT the grid to be powering your home and 100% of your PV to be charging your batteries. From my experience, the algorithm is fairly conservative. That is better than making you draw from the grid at peak time.

There isn't a way that I am aware of to force the system to store 100% of the PV during off peak and also export 100% of the PV during peak.
Self Powered ignores Time of Use and both of the flavors of Advanced have algorithms behind them that you can't manipulate.

I've read that some people setup their off peak, shoulder, and peak times to not match their actual TOU times because they are trying to game the behavior.
I don't subscribe to that philosophy. I have mine set to Balanced, matching off peak and peak times (TOU-B doesn't have shoulder / partial peak) and 15% reserve. I'm quite happy with the behavior. There isn't a way to make it better without A) installing more PV or B) decreasing home kWh usage.

P.S. I also used to be very focused on the NBCs. I now don't care because I feel that Advanced mode has the priorities correct.
My NBCs are about 10% of what my off peak rate costs. So I figure that I would rather use cost saving, have my powerwalls full and send to the grid. I have my Tesla start charging at 12:30pm since the powerwalls are full by then and that way at least half the car is charged by solar.

I specifically start charge at the half hour mark because the NBCs are calculated on the net for that hour. So if the solar sends 5kwh to the grid for 12:00-12:30 and I take 7kwh from 12:30 to 1:00 I am skirting 5kwh of NBCs.

Even then, since the NBCs are 10% of my off peak pricing and the PW have a 9% return loss, I figure I will exercise the batteries less since it’s basically a wash. I would rather be self sufficient for sure, but by sending to the grid my neighbors are using my excess renewable energy (while SCE marks it up 10x for doing essentially nothing but I digress). By stretching out the lifespan of the powerwalls, I am also lessening my impact by getting more usable time out of the batteries.

That’s just how I look at it.
 

arnolddeleon

Supporting Member
Supporting Member
Jul 21, 2012
894
948
SF Bay Area
The main thing I don't like about Balanced is it will draw power from the Powerwalls during off-peak hours in the morning. Having backup power was my main objective of getting the Powerwalls and I want them to have as much reserve as practical during off-peak hours.
Cost savings mode prioritizes recharging from solar in the mornings and then diverts power to the house/grid once the batteries are charged.
I think this is a feature. Balanced is trying to also increase self consumption. The algorithm probably figured you didn't have battery in the evening to continue self powering for the entire evening but you had some energy to give. So it stops discharging early. The system could naively just keep discharging until it hits your reserve. That would leave your sitting at your reserve most of the night. What I think it is doing is to forecast when to start discharging so it gets to down reserve just as PV generation kicks in. This minimizes the time your at low state of charge while still. This was the behavior I was seeing when I only had two Powerwalls. I've really grown to like "balanced".
 
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h2ofun

Active Member
Aug 11, 2020
2,932
562
auburn, ca
Why? I have only one and that is plenty. One can easily cover my house of a whole day without any sun at all.

You realize more people in CA have gas for all major loads
Yep, I know that. How long can you run AC? When it is 110 out side, and the sun pounding the west facing side of my house, the AC is on big time. But, I do have a large house. Thats great if one works for you!!!
 
Mar 15, 2021
279
114
California
Yep, I know that. How long can you run AC? When it is 110 out side, and the sun pounding the west facing side of my house, the AC is on big time. But, I do have a large house. Thats great if one works for you!!!
The rare time there is an outage and I would need to run the AC, the only time I would need to run the AC is when the sun is out. That is not an issue since the sun is out and we are producing more than enough solar
 

h2ofun

Active Member
Aug 11, 2020
2,932
562
auburn, ca
The rare time there is an outage and I would need to run the AC, the only time I would need to run the AC is when the sun is out. That is not an issue since the sun is out and we are producing more than enough solar
You are lucky. The hottest time of the day is late evening where the sun is not up, if at all, for that long.

I am not talking about an outage. If your batteries are in backup mode only, then would not matter
 

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