jhn_
Member
Here are the FAQs from the utility and Tesla. Note that Tesla keeps 20% of the payment from the utility for operating the program, hence why the utility says $50/kw in the winter and Tesla says $40.
Powerwall discharging to grid
- Thread starter Rich121
- Start date
Somebody in CT has the same/similar program, and it seems to be the same idea as what you linked - the payment is based on your "average contribution" in kW. For summer, that can be up to 60 three-hour events, and 5 in the winter. Since they pay $225 in the summer for up to 180 hours and $50 for up to 15 hours in the winter, that works out to a price per kWh of at least $1.25 in the summer and $3.33 in the winter (before Tesla's cut,) both of which are great deals. And, if they don't max out the number and length of the events, the value only goes up.
Of course, the down-side is that you have to pay for the PWs and there is a risk that exporting to the grid could result in you not having access to as much backup power should there be an outage the night after an event (since the events are scheduled 2-7, in most cases there will be little or no solar until the next morning to re-charge.) But, with the potential to make over $500 (and maybe up to $1000 with perfect circumstances) per PW, that can definitely help offset the costs.
Ampster
Active Member
In California, there are plenty of upsides to having solar and batteries as you point out. It all depends on where you are standing.
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Ampster
Active Member
From my California perspective, the brownouts that were experienced last August were from 5PM to 9PM and there was plenty of capacity from 11PM to charge Powerwalls from the grid.
Ampster
Active Member
I don't know, but I only think that program would be used to support the grid to avoid scheduled brownouts. Local or even large grid failures due to other factors are certainly possible.
My hope is that more DER resources will be brought online to make the grid more resilient. I am not waiting for the regulators to figure that out. I have already made an investment in my own hedge against uncertainty.
Yeah - that is the kind of risk I am thinking of. If you sign up for the program and choose to maximize your earnings by not setting a reserve, you could completely deplete your battery (PW has 13.5 kWh storage, with a 5 kW maximum continuous discharge rate, so a 3-hour event could do so if there is not also solar available to charge during that time.) If the event ends at the later time - 7:00 - you probably won't be able to put much back into the battery until the next morning. If a summer storm hits overnight, you might be without sufficient backup power.
And, to be clear, my point was not to criticize the program - I would seriously consider signing up should our area have such a program. The point is just to recognize there are tradeoffs. The more of your battery capacity you make available to the grid, the less you have for use as backup should you need it. What the right balance is depends on the individual's assessment of their own circumstances.
jhn_
Member
Tesla’s docs for the program say they won’t discharge your battery system below 20%. But even if you have a reserve of something higher in the app settings, say 30%, that backup reserve will be ignored during a Connect Solutions discharge event.
I figured for our setup, I could live with the 8kwh being left as a backup in the worst case scenario that our 3 Powerwalls were not very full when the Connect Solutions discharge began.
I figured for our setup, I could live with the 8kwh being left as a backup in the worst case scenario that our 3 Powerwalls were not very full when the Connect Solutions discharge began.
jhn_
Member
Another “grid services” event here on National Grid utility in Massachusetts today. Panels have been solely charging the Powerwalls all day and expect to see a lot of it discharge to the grid between 2-7pm.
Do you get some sort of notification that an event will occur? I get an alert from Chargepoint when an EVSE limiting event is going to occur, and received one of those today for 5-7pm. But I haven't gotten anything from Eversource when there is going to be a powerwall discharge event. Or at least I haven't yet. I guess I'll find out at 5pm if my powerwalls go to the grid.
jhn_
Member
From what I’ve read it’s up to the “administrator” of the program to send the email notices. SolarEdge says they do it for their battery customers. Sounds like ChargePoint does from your experience. Tesla does not notify by email and says the notification is in the app.
I would prefer an email. SolarEdge includes a link in their email notification that lets you opt out of individual events. That would be nice too.
I would prefer an email. SolarEdge includes a link in their email notification that lets you opt out of individual events. That would be nice too.
I would prefer that as well. The ChargePoint EVSE email does allow opt out. Today was indeed a discharge event for Eversource. The Tesla app didn’t have a grid services button, just shows the discharge to the grid in the graph. It didn’t show an arrow to the grid on the animation either. Does yours show those?
jhn_
Member
Hmmm. Is that an android or iOS device? Maybe the iOS device I have doesn’t show grid services yet.
jhn_
Member
Tesla manages mine too. I wonder if they have something not set up right in my account. Wouldn’t surprise me. Could be that I’m on Eversource and you’re on national grid. Looks like the OP, also on Eversource, had similar looking charts to me and no grid services.
Another difference is that I keep my system in backup only which leaves my batteries full most of the time. I do this because here we have 100% net metering so I get full credit for what I push to the grid from solar. So the system doesn’t need to manage charging the powerwalls before the event.
