newbie here. just got pto from socal edison last week on a 6.6kw system + powerwall 2. sce just switched us over to the tou-d-a plan. we also recently leased a chevy bolt and installed a level 2 charger. i was wondering if anyone had any suggestions on how to maximize everything to save money. minus the bolt charging, we've been able to charge up the battery during the day and use it to power the house at night with a little (depending on the day) power going back to the grid. now that we're on a tou plan and have the bolt, i scheduled charging for late at night. the battery was taken down to the backup percentage (10%) so the house had to pull from the grid until the sun came up. is that the best i can do during these winter months? is there anything else you guys suggest i try?
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solar panels + powerwall 2 + chevy bolt. need advice on battery settings
- Thread starter alleyooptroop
- Start date
Tam
Well-Known Member
No expert here:
1) If you net production during daylight is positive, maybe you should charge your Bolt during that time.
If doing so would result in negative net production and you have to pull the difference from the grid then it's better to go back to what you are doing now: charging at super offpeak hours for cheaper rate.
2) Sounds like you need an upgrade for bigger battery capacity storage which also means an upgrade for bigger capacity from solar panels too.
nwdiver
Well-Known Member
What's your TOU schedule? For most places it's cheaper to export during the day and import from the grid at night.
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How is your consumption vs. production? Do you end up paying money at true-up or not? This is a key factor on how to optimize. If you aren't covering all of your usage, you want to maximize your export during peak hours so you get a higher credit. This means you want to use your Powerwalls in cost savings mode mainly to offset your house usage during peak hours. You then want to charge your Bolt at night directly from the grid during off-peak rates. Even though solar is free to you, you can earn money for it by exporting to the grid, so you don't want to use it during peak hours.
Do you have Time Based Control yet? It takes a little time after Powerwall installation for those options to show up in the Tesla App. I recommend the TBC-Balanced mode. When you turn that on, charging the car overnight will not drain the Powerwall battery. That will maximize your NEM credits in the Peak and Part-Peak rate periods by not wasting your battery energy by discharging in Off-Peak.
i found the time based control option a couple days ago and currently have it set to balanced mode.
for the most part the panels are producing more than we're consuming. and since i've set the battery to time based control the bolt is charging in the middle of the night (i set the charging software to do this).
The question actually is are you producing more than you are consuming on an annual basis. That is, will you owe money at your annual true-up or will you have a credit balance (and possibly overproduction for the year).
If you have a credit balance over a typical year, the Powerwalls won't do much except increase your credit balance. Unless you have joined a community choice aggregator, you probably don't get the credit paid out, so the Powerwalls won't help much.
If you have a credit balance over a typical year, the Powerwalls won't do much except increase your credit balance. Unless you have joined a community choice aggregator, you probably don't get the credit paid out, so the Powerwalls won't help much.
producing more than i'm consuming is the expectation if my system was designed correctly (knock on wood). i'm only a couple weeks in so time will tell. i'm trying to understand how the time based control would benefit me more than just having it set to self powered. before the bolt/level 2 charger the system produced enough to charge up the battery (with some back into the grid even at this time of year) that would power the house all the way up to when the sun would come out the next day to start all over again. no power from the grid. the bolt is only driven as an errand runner (groceries, picking up kids etc) so it only needs about an hour of charging to get back up to 100%. it'd be great if i could set up the battery to stop for an hour in the middle of the night for the bolt to charge from the grid then turn back on to power the house. or is this too simplistic of a view?
Since we don't have the option under self-powered mode, you can use TBC-Balanced to accomplish what you are trying to do.
In my case, I extended the hours of the shoulder (part-peak) period so that they go until 5 am instead of ending at 9 pm. That way, I'm self-powered except for a few hours in the morning, when our cars charge between 5 and 9 am, which I have set to off-peak.
Using TBC-Balanced mode does have some other quirks but we're using this setting since it allows us to set the hours the Powerwalls power the house. Hopefully they'll add similar functionality to the self-powered mode in the future.
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If you want it to work more like that in TBC-Balanced, you can reduce the Off-Peak hours in the schedule to only the hours when you charge the car. However, from a financial point of view, I would just leave it on the real utility schedule and see how the year progresses. If you are running a big surplus when Summer hits, you can set your thermostat to a more comfortable temperature and let your A/C run more.
this is great. so with this set up is your battery getting charged to 100% during the day? would love to see a screen shot if you wouldn't mind.
Unfortunately, that's one of the quirks I was referring to with TBC-Balanced. Sometimes it charges it up to 100%, sometimes it only goes to 80%. Some days, it doesn't get anywhere close! It tries to learn your typical usage and end up close to the reserve. I have mine set to 25% and usually when I wake up in the morning, I can see it is at 25% to 28%. Most of the time, it stops right at 5 am. Other times, it hits the Powerwall reserve in the middle of the night and then the house it powered by the grid.
My real TOU hours are:
9 am - 2 pm part-peak
2 pm - 6 pm peak
6 pm - 9 pm part-peak
9 pm - 9 am off-peak
In order to self-power the house on a schedule, I have the Price Schedule set slightly differently:
9 am - 2 pm part-peak
2 pm - 6 pm peak
6 pm - 5 am part-peak
5 am - 9 am off-peak - Not using Powerwalls to power house or cars during this period
This way, my house is usually self-powered for all but 4 hours of the day. During those hours, we charge the cars. We used to try self-powered with the cars but with 3 Teslas actively charging, they would drain the batteries pretty quickly. We can cover one or two of them, but not all three. We often produce enough solar power during the day to offset the grid usage when charging the cars. So we aren't 100% self-powered yet but do try to offset whatever we take from the grid.
Here's a screenshot showing my Price Schedule for TBC - Balanced.
One of the other quirks of TBC - Balanced is that it prioritizes sending power back to the grid. While I have peak set to start at 2 pm, it often starts exporting everything back to the grid several hours early. Some days, I do wish it would charge the Powerwalls more so I can increase the reserve or temporarily switch to self-powered.
In the other screenshot, you can see how the Powerwalls try to power the house except from 5 am until the sun comes up.
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Thanks so much for posting this. since we've only got the bolt that only needs about an hour i wonder if i set my off peak to a couple hours in the evening if that would do the trick.
I just added another screenshot showing the actual Energy Usage. See my updated post above or the attachment here: View attachment 356432
Let me know if you need help interpreting the Energy Usage graph.
You could set your "off-peak" time any time during the real off-peak period. We live in Colorado and have our cars charge in the morning so that we can warm up the batteries and they finish charging right as we leave for work. If you don't need to worry about that, you could do it any time during the off-peak period.
this seems like a great strategy to try. of course today it's raining here in LA but once the clouds move through i'm gonna see if this works. thanks again.
Try changing your off-peak to 5am - 2pm, this will stop the PW from discharging before your peak period.
eml2
Member
But what will happen if there is solar generation during off-peak? Will it export everything to the grid, or will it charge PW with excess solar (after covering the house load)?
I don't mind if they discharge before peak. I just wonder why it doesn't always charge them up fully. Lately, it seems more predictable, so maybe it really was "learning" my average household usage. They get up to 80% most days now. I don't know if it is doing it to minimize battery cycles or what.
Anyhow, that is an interesting suggestion that I'll have to try.
