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Adding more time on the powerwall during off peak
- Thread starter Merrill
- Start date
Then I suggest TBC-Balanced with Peak 4-9pm and Off-Peak Midnight to 8am. Set the pumps to run 9am-3pm, during the PW shoulder period. I think that's your best chance for the PWs to act like Self-Powered while the pumps are running while still filling the battery for use during the Peak hours. If you have a lot of left over energy then it will continue to power the house until midnight. If you have an EV, you can charge it from the grid after midnight. Of course, if you and the car are home during the middle of the day, you can charge directly from solar too.
Thanks for your help, I assume that once I set the above everything in gray is shoulder. I have a separate meter for EV charging so will not effect the house. How would this effect my solar credits going to the grid.
Yes, gray color is the shoulder hours. Honestly, the rate differentials in TOU-C are so small that the financial impact of the battery flows is not that significant. We just started the Summer rate season on June 1 and the Peak/Off-Peak difference is only a little over 6c/kWh. 8 months of the year have rate difference of less than 2c/kWh. As long as you have the Peak hours in the Powerwall settings matching the 4-9pm Peak rate window, all your solar will be exported for credit at the higher rate. Since you have an EV meter, maybe just run in Self Powered in the Winter months, raising the Reserve when the solar generation gets low and Winter storm power outages become more likely.
Actually I looked at the numbers during peak 4pm to 9pm and the additional cost for those 5 hours at peak is minimal. I’m thinking of running my peak during the 6 hours in the morning when my pool is filtering and my irrigation is drawing from the well. I know that is the most electricity I use in a day.
If you're not going to let Time Based Control cover the Peak hours of the rate plan, you might as well run in Self Powered mode. That is, unless there are times that you DON'T want loads to use the battery.
Another question, so I want to understand how solar production going to the powerwall to charge during afternoon high solar production. My Powerwalls stop powering the house at 10am and are down to 15% and then they start charging from solar it takes most of the day to get back up to 100%. I notice that most of the solar is charging the Powerwalls, some to the house and nothing being used from the grid. Is it a problem that the solar is not going to the grid from a financial point of view.
As long as you're not wasting battery cycles charging and discharging during the same rate period (like Off-Peak), then it shouldn't make a difference. The bad part would be taking the charge/discharge losses without any benefit. Since I am on NEM 1.0, I really don't want the Powerwalls to ever discharge or power my house during Off-Peak. It's better if the battery just sits there and lets the house draw from the grid. That just means that the solar charging will finish sooner and I will get NEM credits earlier in the afternoon to offset the grid energy I used in the morning. Now, if you're on NEM 2.0 and have to pay NBCs, then you can avoid the NBCs by using Powerwall energy before the sun comes up and recharge it later in the day.
Thanks for your help, since I use very little energy during peak 4pm to 9pm I’m not saving much money by having the Powerwalls run the house at that time. 90% of my kW usages is when the pool filters and the irrigation is running which is from 4am to 10am so that is when I have the Powerwalls run the house. So because of this at 10am the Powerwalls are at 15% and take until 3pm to get back to 100% so most of my solar goes to charging the Powerwalls. I’m still not sure what setting would be best for my situation.
Honestly, between the fact that you're on TOU-C (small price differentials), don't have much usage in 4-9pm, and have a separate EV meter, it may not matter much financially which mode you choose. You should probably just try different settings and see how the system performs for a week or two at a time and see which one you like the best, based on your personal preferences.
The bigger question is whether there is an opportunity to save money by changing the rate plan and changing the Powerwall settings to optimize against that. It really depends on your net kWh over the year and your prior true-up dollar balance. If you're been negative dollars in prior years or are close to zero net kWh, then there may not be much or any opportunity for cost improvement.
I was on E6 before the paired storage and they made me switch TOU-C to be able to get the SGIP incentive. I do not have enough solar to be net, my true up last year was around $450. Based on my first few months on paired storage it looks like my true up will probably double and that is why I’m trying to minimize grid usage. This time of year my solar produced around 1200kW a month and my usage is around 1300kW so you would think I would owe nothing.
Wouldn't it be better to run the pool filters and irrigation during the middle of the day when your solar production is highest? Then the power goes straight from the panels to the equipment, avoiding the 10% roundtrip losses of banking it in the Powerwall every day, not to mention the daily cycling 85% on the Powerwall. The cost wouldn't be any different on TOU-C running it between 4-10am vs 9am-3pm, it's all off-peak.
Now your Powerwalls aren't doing much, except being a power outage Backup. But without much peak usage, you're not saving anything time-shifting from off-peak to off-peak, just putting wear and tear on the Powerwall longevity. You have to arbitrage using a different plan where you can shift peak grid-draw to off-peak.
Have you considered putting the house meter on EV2-A? Since you have batteries you are eligible for that plan. The Powerwalls would enable you to zero out or have negative Part-Peak and Peak usage for a significant part of the year while making the bulk of your Off-Peak usage significantly cheaper. For me, most of my annual costs are incurred in the 4 months with the least generation where the solar and batteries don't cover the Peak usage.
@wwu123 it's probably not ideal to run the irrigation during solar hours for water usage and evaporation considerations. Pool pumps, sure, no difference what part of the day those run.
just seems too many think batteries will save them a lot of money. for many ends up costing them plus all the issues dealing with them. if not for sgip i never would have gotten any. for me generator is easier to deal with. only had one outage last year for a few hours. imo o e maxing out ones solar on nem2 is a much better return
While I also would not have gotten Powerwalls without SGIP, I could not bring myself to pull the trigger on the generator that I pre-wired and pre-plumbed gas for when I built the house. However, my situation is different than yours and I can understand why you feel the generator is a good solution.
Since my solar is small, I do get real bill reduction and eventual ROI from the Powerwalls.
