How do I prioritize solar for self consumption when using Time Based Control?

[wwhitney]

In fact I don't know if prioritizing solar for self-consumption wouldn't knock me over the threshold.

Maybe just run self-consumption for a year and see how the bills turn out?

If you're a net zero kWh importer/exporter, then the only way you have a bill in dollars is NBCs and if you are net importer during peak. The more you are a net kWh exporter, the more you can afford to be a net importer during peak, as it will be offset by all your net exports during off-peak. So minimizing NBCs may be more important cost-wise than avoiding any grid draws during peak.

You could also try TBC with all your sell rates set to 7 cents/kWh, and your buy costs set to what you'd pay if you aren't a net dollar exporter. That should incentivize the control algorithm to self-consume rather than sell back, and to prefer off-peak grid draw to peak grid draw. It won't incentivize it to time shift production to export at peak, but seeing as how you are a net kWh exporter, you don't also need to be a net kWh exporter during peak to avoid having a bill in dollars.

Any experiment like the above should be run at least a week to give the algorithm a chance to stabilize, probably more like a month.

Cheers, Wayne

 

[RKCRLR]

Maybe just run self-consumption for a year and see how the bills turn out?

If you're a net zero kWh importer/exporter, then the only way you have a bill in dollars is NBCs and if you are net importer during peak. The more you are a net kWh exporter, the more you can afford to be a net importer during peak, as it will be offset by all your net exports during off-peak. So minimizing NBCs may be more important cost-wise than avoiding any grid draws during peak.

You could also try TBC with all your sell rates set to 7 cents/kWh, and your buy costs set to what you'd pay if you aren't a net dollar exporter. That should incentivize the control algorithm to self-consume rather than sell back, and to prefer off-peak grid draw to peak grid draw. It won't incentivize it to time shift production to export at peak, but seeing as how you are a net kWh exporter, you don't also need to be a net kWh exporter during peak to avoid having a bill in dollars.

Any experiment like the above should be run at least a week to give the algorithm a chance to stabilize, probably more like a month.

Cheers, Wayne

I agree with what you are saying, I just don't want to risk a big bill at true-up because I didn't track what the self-consumption mode was doing close enough. Plus my experience with it was erratic and I didn't understand what it was doing.

I'm trying @BGbreeder's TBC settings to see how they work. So far it isn't looking good. Yesterday it still sent all solar to the grid during part peak and peak, and continued to run my home off the Powerwalls during off-peak when solar wasn't producing. I'll give it some time to see if it settles down.

 

[wwhitney]

But with EE, as it time shifts the solar, is that allowed under our rules?

Pretty sure yes in principle, and definitely yes in practice, as the bill just checks that the total export does not exceed the modeled PV production over the billing cycle.

Ie I put it in the PWs during off or partial peak and then TBC dumps the PWs energy to the home and excess to the grid along with currently generated solar? Also does this seem to work? ie will the PW get to the end of peak at the reserve? I guess I need to turn it on and try it.

Yes, it seems to work fairly well. For me, when I've looked at the graphs, it tends to do max export at the start of peak, until it reaches a level of charge above reserve that it estimates is required for the remaining peak usage. Sometimes its estimate is off, and you end up with a bit of grid draw at the end of peak. Which is suboptimal with NEM2, but a small effect compared to the benefit of exporting at peak vs off-peak.

Cheers, Wayne

 

[TTSSBB]

Hi, I am new to this and finally got my install done and PTO up. I am on PGE, TOU EV2A, have 17.2kW + 3PWs.

I am wondering:

i) is TOU better vs. self-consumption since I can fully power my usage, fill my PWs and then run my PW's when Solar wanes...any excess goes to grid. If I use TOU, I get net export but I also consume from grid. Does the true up count the KWHrs I import from during times of day differently from what I export?
ii) If I stick w/ TOU, should I toggle on the grid charging of my PWs?

 

[TTSSBB]

Cont'd from above. I read that since Jan 2023, there is no issue w/ Tax incentives if charging battery from the grid if the install was done in 2023. I am on Nema 2.0 (application sent before deadline...but install completed after...hope it comes out as they say).

Many thanks in advance for the more experienced!

 

[jjrandorin]

Plus my experience with it was erratic and I didn't understand what it was doing.

I use only Self consumption mode (Still on NEM 1.0 and on a tiered plan, not a TOU one). As far as what self consumption mode does, its pretty simple (compared to the TOU modes, at least from my reading about those here). Self consumption doesnt have fancy learning algorithms or anything, nor does it pay any attention at all to buy / sell rates etc. All it seems to do, to me is:

1. Use any available PV to power house loads.

2. If PV production > than house load, send any additional PV to powerwalls, until powerwalls reach 100%, only export to Grid when PV production > house load, AND powerwalls = 100%

3. If PV production doesnt cover house loads, and Powerwall capacity > than reserve, use Powerwall to supplement PV to cover house loads, until Powerwall reaches reserve setting.

4. If Both of the above are still not enough to cover house loads, then and only then pull from the grid.

5. Continue the above settings regardless of whether PV is generating or not. Powerwalls will run the house until they hit the reserve. If powerwalls never hit the reserve, even after being used overnight, no grid power is used (except for what is required to actually run the powerwalls it seems, about 200w a day for my 2 powerwalls).

Basically, self consumption does "what it says on the tin", in that it prioritizes not pulling from the grid, and the grid is only used when there is no other option to meet the house load (meaning Not enough or no PV, and not enough powerwall power or powerwall at reserve).

Peak / Off peak / Partial peak do not matter at all in self consumption mode, and one complaint some may have that use this mode (including me) is that if you have an EV, even if its set to charge in the middle of the night, when it starts charging it will quickly drain your powerwalls down to their reserve, before your car will charge from the grid.

I have my reserve set in such a way that my home tends to hit the reserve shortly before my car starts charging, but of course that changes depending on time of year, etc so I end up messing with my reserve sometimes.

 

[RKCRLR]

This is what I use and we have essentially zero draw on peak.
View attachment 960804

The result is nothing but trivial draws from the grid when a large load kicks in within the house during peak. 80% for Powerwall use, though we rarely use more than 15% of the total storage on any given day.
View attachment 960805

Well, I've tried your settings for over a week now and am not getting the same results you do. During partial peak and peak hours all solar power is being sent to the grid and my house is running off the Powerwalls like it did with my original settings. However, during off peak my house continues to run off the Powerwalls through most of the night until I hit my reserve. There is some draw from the grid during higher draws from the house during the off peak. I don't mind this but my objective of all this is to prioritize my solar power to my house during partial and peak hours.

 

[RKCRLR]

I use only Self consumption mode (Still on NEM 1.0 and on a tiered plan, not a TOU one). As far as what self consumption mode does, its pretty simple (compared to the TOU modes, at least from my reading about those here). Self consumption doesnt have fancy learning algorithms or anything, nor does it pay any attention at all to buy / sell rates etc. All it seems to do, to me is:

1. Use any available PV to power house loads.

2. If PV production > than house load, send any additional PV to powerwalls, until powerwalls reach 100%, only export to Grid when PV production > house load, AND powerwalls = 100%

3. If PV production doesnt cover house loads, and Powerwall capacity > than reserve, use Powerwall to supplement PV to cover house loads, until Powerwall reaches reserve setting.

4. If Both of the above are still not enough to cover house loads, then and only then pull from the grid.

5. Continue the above settings regardless of whether PV is generating or not. Powerwalls will run the house until they hit the reserve. If powerwalls never hit the reserve, even after being used overnight, no grid power is used (except for what is required to actually run the powerwalls it seems, about 200w a day for my 2 powerwalls).

Basically, self consumption does "what it says on the tin", in that it prioritizes not pulling from the grid, and the grid is only used when there is no other option to meet the house load (meaning Not enough or no PV, and not enough powerwall power or powerwall at reserve).

Peak / Off peak / Partial peak do not matter at all in self consumption mode, and one complaint some may have that use this mode (including me) is that if you have an EV, even if its set to charge in the middle of the night, when it starts charging it will quickly drain your powerwalls down to their reserve, before your car will charge from the grid.

I have my reserve set in such a way that my home tends to hit the reserve shortly before my car starts charging, but of course that changes depending on time of year, etc so I end up messing with my reserve sometimes.

That makes sense although I seem to remember some seesawing back and forth between charging and discharging the Powerwalls. My main concern with self consumption is during the winter I would hit my reserve during peak or partial peak hours and draw a lot of power from the grid during those hours. I think I'd be OK during the summer on self consumption but I don't know if I'd send enough back to the grid to offset the winter peak and partial peak consumption.

 

[jjrandorin]

That makes sense although I seem to remember some seesawing back and forth between charging and discharging the Powerwalls. My main concern with self consumption is during the winter I would hit my reserve during peak or partial peak hours and draw a lot of power from the grid during those hours. I think I'd be OK during the summer on self consumption but I don't know if I'd send enough back to the grid to offset the winter peak and partial peak consumption.

That makes sense.

Note that its definitely possible to see see sawing back and forth between charging and discharging. That would depend on the home load vs the PV production. If (for example, your PV was generating 2kW and your home load was 1.5, that additional .5 would be going toward the powerwalls if they were not full.

Then, if you have a spike in consumption (like you turned on a toaster oven / microwave), your home load might go from 1.5 to 2.5kW, and your powerwalls would switch from being charged by the additional .5 of PV, to discharging .5 of PV. It happens very fast, too (within a second or two in the app, but thats with showing the data, so I am sure the switch is milliseconds). After the toaster / microwave finished, it would switch back.

If its a cloudy day and your PV production is going up and down, and sometimes it covers your home load and sometimes it doesnt, the Powerwalls would switch from charging to discharging, as appropriate, to cover the home load or soak up additional PV.

It basically just prioritizes "dont use the grid" and it may not be appropriate for someone on a TOU plan, since there is no consideration whatsoever about peak, off peak, etc. Thats why I think its "simple" compared to the others.

Still, its likely not the right plan for someone on a TOU plan, unless they have other goals (like "i dont want to use grid power"). Its still appropriate for me, since I am still on a tiered plan.

 

[GregBallantyne]

I use only Self consumption mode (Still on NEM 1.0 and on a tiered plan, not a TOU one). As far as what self consumption mode does, its pretty simple (compared to the TOU modes, at least from my reading about those here). Self consumption doesnt have fancy learning algorithms or anything, nor does it pay any attention at all to buy / sell rates etc. All it seems to do, to me is:

1. Use any available PV to power house loads.

2. If PV production > than house load, send any additional PV to powerwalls, until powerwalls reach 100%, only export to Grid when PV production > house load, AND powerwalls = 100%

3. If PV production doesnt cover house loads, and Powerwall capacity > than reserve, use Powerwall to supplement PV to cover house loads, until Powerwall reaches reserve setting.

4. If Both of the above are still not enough to cover house loads, then and only then pull from the grid.

5. Continue the above settings regardless of whether PV is generating or not. Powerwalls will run the house until they hit the reserve. If powerwalls never hit the reserve, even after being used overnight, no grid power is used (except for what is required to actually run the powerwalls it seems, about 200w a day for my 2 powerwalls).

Basically, self consumption does "what it says on the tin", in that it prioritizes not pulling from the grid, and the grid is only used when there is no other option to meet the house load (meaning Not enough or no PV, and not enough powerwall power or powerwall at reserve).

Peak / Off peak / Partial peak do not matter at all in self consumption mode, and one complaint some may have that use this mode (including me) is that if you have an EV, even if its set to charge in the middle of the night, when it starts charging it will quickly drain your powerwalls down to their reserve, before your car will charge from the grid.

I have my reserve set in such a way that my home tends to hit the reserve shortly before my car starts charging, but of course that changes depending on time of year, etc so I end up messing with my reserve sometimes.

Less than 3 months of operation, but this is how I operate. I've been self powering since. And when you're self powering, the best reserve is the recommended 30%. If the grid goes out, your behavior doesn't require altering. You want as much battery capacity available to you as you can have, and you start thinking about another PW or two..... and charging the car gets a little more complicated, requires more attention. Messing with the reserve a little comes into play, used as a control.
I tried putting in the rate plan, and immediately noticed behavior I thought was rather odd. Then I found out that BGE (Baltimore Gas & Electric) wasn't going to change me to the TOU plan anyway, they don't let customers with solar generation use that. The self powered mode isn't perfect, but suits me better that the TOU operation mode. I didn't spend any time trying to make sense of it, just assumed it was all about lowering your bill, as stated, and resulted in operation I didn't want anyway. And when I'm self powering, by bill is just the minimum connection fee, less than $10. My excess to the grid is banked for winter when I likely run short of generation, and if not used a yearly reimbursement occurs. Now I'm just waiting for the software in the car to catch up so as to charge the car on excess solar...

 

[RKCRLR]

Well, I've tried your settings for over a week now and am not getting the same results you do. During partial peak and peak hours all solar power is being sent to the grid and my house is running off the Powerwalls like it did with my original settings. However, during off peak my house continues to run off the Powerwalls through most of the night until I hit my reserve. There is some draw from the grid during higher draws from the house during the off peak. I don't mind this but my objective of all this is to prioritize my solar power to my house during partial and peak hours.

I'm still using these settings and all solar during partial peak and peak is still being sent to the grid. However, there seems to be some logic now being used to keep me from hitting my reserve. The system still continues to run off the Powerwalls during off peak at night but appears to do some modulation by sometimes drawing power from the grid to keep me from hitting my reserve before morning.

I don't mind the way it is operating off peak but I would still like to find a way to prioritize solar to home consumption during partial peak and peak hours while still respecting TOU hours. I wish there was a hybrid self-consumption mode where you could tell the Powerwalls you want to avoid drawing power from the grid during partial peak and peak hours.