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PW's discharge rate during "Grid Services" event.
- Thread starter solarAddict
- Start date
jhn_
Member
Yeah I was really surprised to see grid services events both Thursday and Friday when things had cooled down. Monday was in the 90’s and no event. Tuesday and Wednesday pushing 100F and both days were events. Thursday was 80’s and an event. Then Friday was rainy and barely 60F and still an event pushing all power to the grid. 
I was in this program and absolutely could not get out fast enough once I realized they were commandeering my battery both the night BEFORE and the night AFTER an "event" if they are anticipating an event the following day. Essentially meaning that I had NO use of my battery at nighttime (because Tesla has it in "aggregate mode" and battery would be in "standby" mode) as I had before the "events" started. And during the day they have the grid power my house so that all solar went toward powering the PW the day before an "event." I had NO control over this. The final day before I was able to unenroll I just turned off the battery so my solar would go toward powering my house FIRST like it's supposed to, instead of Eversource stealing it.
The person at Tesla who finally helped me unenroll said it best, "yes, we knew it was an imperfect program but as one of the largest solar providers, it wasn't good politics to say no we won't participate. Admittedly, my system is a smaller one, but there is so little detail given when you sign up for the program, and when I had questions prior to signing up, no one at Eversource knew anything (in CT they have outsourced this program to a third party facilitator called "EnergyHub" and there is no reaching anyone at EnergyHub. The kicker is that you have to stay in the program the entire season to see any money--so by disenrolling I forfeited the money that Eversource/Tesla essentially stole from me (potential KW from my solar). And one of the posters above is correct--NO ONE is able to tell me exactly how the payments are calculated or how one might do a rough calculation as to what to expect. I get that there are sun/weather variables and etc., but it's pretty sketchy IMHO.
I have screenshots of all this, but I don't know if they would make any sense to anyone. You can see the grid powering my house when there is adequate solar to do so....but it's ALL going to the battery.
I have a different perspective on connectedsolutions on Eversource than you expressed above. In the end, Eversource doesn't ever "steal" power, they pay for it, actually quite a lot per kWh. They certainly do a lousy job explaining how much you'll get and they take forever to pay it, I won't defend that. Also, I can only comment on the program with Eversource in Mass where I live.
The incentive they offer in eastern MA is $225 for summer and $50 for winter. This incentive is paid per kW you are providing on average during the season's events. In my case they typically discharge 30kWh over a three hour period so the rate would be 10kW. So I'd expect my payment to be about $2250 for the summer. If there are the maximum events that they expect (60) that works out to about $37.50 per event. If there are fewer events, it would be more. Since they discharge 30kWh (for my three powerwalls) per event that is getting paid >$1 per kWh. A pretty good payment, even if it takes them 5 months to pay it. Not to mention the 30kWh also either supplies my house or turns the meter backwards then too and so with the 1:1 net metering we have here, it is also a win there. The only downside I see is that the power that goes to the battery before going to my house or the grid has only a 90% payback vs the power going in to the battery due to the systematic loss. Easily made up for by the large rate they end up paying.
With 1:1 net metering, I am actually better off financially leaving my battery full, and spinning the meter backwards when I have excess generation, rather than cycling the battery. I normally leave my system in "self powered" mode with 85% reserve for power failure just so that the battery cycles some which is a requirement for the SMART program's battery incentive ($.04/kWh). They say they want at least 58 battery cycles (IIRC) to get that incentive. I suspect that the connected solutions would be providing enough cycling, but I also am guessing that leaving my battery at 85% most of the time is slightly better for battery longevity than staying at 100% all the time, but who knows. With 1:1 net metering, using the battery at all has a slight loss due to the 90% efficiency of the in vs out to the powerwall.
You are right that they try to maximize utilization of your battery for their program. I also don't mind that because I get paid much more with them discharging a full battery during an event. If my battery is empty for an event I lose money in the program since I can't provide power. The purpose of this program is to allow the power company to shift my peak generation to be able to discharge it at their peak load. They are using the batteries of the participants in the connected solutions program as a cushion to prevent them from needing to purchase additional (and likely dirtier) generation capacity at high rates during peak consumption. Your battery becomes a power plant. They will in fact use all of your solar generation to charge your battery and power your house from the grid entirely when preparing for an event. Since we are only allowed to charge the battery from solar generation, this maximizes the power in your battery for the event later in the day or the next day when they need the generation. It does increase grid usage at that point in time, but when you dump it back you "replace" it. You don't lose anything in this trade vs discharging the battery to your house at night off peak.
The only real downside I see is that if there is a powerfailure when the battery has been discharged (to the 20% it goes to) after an event which would leave you hoping for a sunny day the next day. They should be managing storm watch vs connectedsolutions events, but others have noticed that they have a problem with this need to dramatically improve this linkage. I personally haven't had a problem with this, but now that I've said that I hope that I haven't jinx'd it.
In MA between the battery incentive kicker and connected solutions payouts, it really put a dent in the cost of a system pretty quickly and made it reasonable for me to buy the powerwalls, even though our favorable net metering makes them less necessary. I love the idea of having them for backup power and that they allow generation to continue even with the grid out.
Question for you. Does the amount sent back to the grid under grid services factor into the incentive amount. I have two powerwalls and during a two hour event they are discharging at 10kw combined for two hours but since the house is using about 1.5 kw the amount seen sent back to grid services shows up as 17kw. So does the grid take the 17kw into account or the two hours of the 10kw the batteries were discharging even though the house was using some of that power in the meantime. Thanks
No, it’s based on the discharge rate of your batteries. So with 2 PW, you’re discharging at a rate of 10kW. The 17 you reference above is kWh not kW. Think the difference of miles (distance) and mph (speed). You’re confusing units of measurement.
Im not confusing the two units. I understand the difference between kw and kWh. my question was about what Tesla used to measure performance because they highlight the kwh amount sent during grid services and I wanted to get the correct answer from people that have been in the system already collecting money
You never sent 17kW to the grid, you sent 17kWh. You can’t sum kW over time and keep using the kW measure. That’s like saying I went 20 miles and then another 30 miles, so I was going 50 miles per hour. The information on the ConnectedSolutions sites are pretty clear that it’s based on average kW and that the kWh don’t matter.
Again yes I understand the difference between kWh and KW. my questions with Tesla is on their grid services tab on the app is that they emphasize KWH sent and not average KW during a connected solutions discharge.
For some reason I don't have grid services showing up in the app so I can't comment on what that reports. It is the amount discharging from your PW which is what you get credit for, doesn't matter if it went to your house or the grid.
Ah okay that makes sense that it’s different on the app for you guys. I have an extra tab on my app that says grid services and it tallies the amount sent back grid during an event. The powerwalls are discharging at 10kw combined but if the house is using the 1.5 kw during the two hours I see only 17 KWH sent towards frid services during those two hours which would mean an average of 8.5 kw instead of the full 10kw towards grid services. This happens even if my solar is producing more power than the house needs. The house still uses the battery during an event and the solar gets sent towards the grid as well
It seems to me that some of the directionality of the electricity flows I have seen in screenshots shown in this forum is artificial. All of the sources and loads are wired together so it is not really possible to send all of the power from the solar panels to the grid while drawing power from the battery to power the home, for example. Assuming the grid is up, the solar inverter will be pushing all* the power that it's getting from the sun towards the common tie point. The house will be drawing its loads from the common tie point. The batteries can also be instructed by Gateway algorithms or utility commands for Grid Services to also push power towards that common tie point or to pull power from that common tie point at various times. If the solar inverter and the batteries are pushing more power than the house is drawing, then the excess will go to the grid. If the batteries are charging and that load plus the load of the house is greater than what the solar inverter is pushing to that common tie point, then the remainder will be drawn from the grid. You can't say that the battery only gets electrons that come from solar power or that electrons from the grid only go to the house. It's just a matter of accounting and limiting the charge rate of the battery to no more than the power that solar is producing.
* In the future, with planned Smart Inverter enhancements, the utility may be able to throttle the solar inverter to protect the grid from overvoltage when the total solar power being injected into a distribution grid exceeds the total load.
This is my second year on Connected Solutions with National Grid. This morning I was in grid services and it locked my battery at 100% once it charged which is normal. Events usually happen at 3, 4, or 5pm. When 5pm hit, the battery went into self powered mode and didn’t discharge. I don’t know if it’s related to the new software but I don’t recall an event being canceled. Before upgrading to app version 4, I had the grid services icon and could track the events. It’s gone in the new version.
Yea I agree it’s only a matter of accounting when it comes to the app. I just found it weird how the
im glad I’m not the only one that saw this. I also upgraded to new app and at 5pm it had a 4k spike discharge and automatically went off and didn’t discharge on probably the hottest day of the year. Hoping it wasn’t a Tesla fault which would lower the average for connected solutions
For those not currently participating, one thing to be aware of is that the frequency and duration of the events isn't consistent across Massachusetts.
My understanding is that it's dependent on the local grid needs and unfortunately, you can't really figure it out in advance of installation.
My mom lives in Acushnet and has EverSource - she's had overwhelmingly 3-hr events, even some called when it's been cloudy and not that warm. As a result, her average kW discharge is down around 6.6 kW. This is resulting in a much lower incentive than if she had more 2-hr events.
My understanding is that it's dependent on the local grid needs and unfortunately, you can't really figure it out in advance of installation.
My mom lives in Acushnet and has EverSource - she's had overwhelmingly 3-hr events, even some called when it's been cloudy and not that warm. As a result, her average kW discharge is down around 6.6 kW. This is resulting in a much lower incentive than if she had more 2-hr events.
I also had that same spike and then revert to normal non-grid services mode. It was weird.
Any idea what the effect of not having net metering is? I’m planning on participating in connected solutions when my system is installed. Im still not sure if power consumption vs production is netted on an instantaneous basis, hourly, daily, monthly etc, monthly would be best. I’m in eastern MA and have national grid. My planned solar is above the 10kW ac cap so I lose the net metering. There doesn’t look to be any net metering allocation available at the moment either.
Something interesting just happened the other day with my mom's event. Her events have always discharged at current SOC down to ~22% or so. The other day, it just went to ~45% at a correspondingly lower rate for the duration of the event. It's like someone decided that they just didn't want as much as she could give them.
Pretty lame because it reduces her incentive
One thing that i am curious about - if you don't have net metering, does that mean you don't have a bi-directional meter? I assume that it means you don't get credit for energy exported but do you also have to pay for the same energy imported back? If so, that's complete BS IMHO. Or does it just mean that you don't have get credit to apply to another bill cycle than the current one?
Just an FYI, apparently, you can apply for an exception to the cap (Net Metering in Massachusetts: What You Need to Know | EnergySage) but no guarantee of approval or a timely one if even approved. Still might be worth the effort.
Pretty lame because it reduces her incentive
It's not just you, my mom's been online since June 12th and still nothing... and yes, she's using the new app version.
I'm not sure exactly on this but my thinking is that if you opted not to participate in Connected Solutions (i.e, your PowerWalls were there for you to use as much of the solar production), then not having NM might not be too bad, as long as your production and usage were relatively close. If you do, however, then it would be as if you didn't have the PWs as grid events export and are subject to net metering benefits.
One thing that i am curious about - if you don't have net metering, does that mean you don't have a bi-directional meter? I assume that it means you don't get credit for energy exported but do you also have to pay for the same energy imported back? If so, that's complete BS IMHO. Or does it just mean that you don't have get credit to apply to another bill cycle than the current one?
Just an FYI, apparently, you can apply for an exception to the cap (Net Metering in Massachusetts: What You Need to Know | EnergySage) but no guarantee of approval or a timely one if even approved. Still might be worth the effort.
So here is what I THINK it means but I haven't had it fully confirmed yet.
What I do know, under the 10kW AC inverter size you get full net metering. You more or less get the full retail rate credit even if you overproduce in a given month. They won't refund you but it accumulates indefinitely. I was originally right at 10kW with the SE 10kW inverter. Tesla isn't installing those anymore and I have two power wall + units which each have a 7.6kW inverter, so 15.2kW ac inverter size. Quite a bit more inverter than I need for 13kW DC of panels. (39 340w panels). Maybe I can add another string of panels on another part of my roof in the future without needing to upgrade inverters, that could be a plus.
If you are over 10kW and you don't get cap allocation, you sell excess power from the month at the average wholesale rate for the month. (As you said, you can apply for it. I was told I should, but there are currently something like 15k people on the allocation waiting list.)
So here is where it is a little fuzzy. I will be on the the wholesale P-rate tariff is typically around $0.03/kWh vs the total delivered retail rate of about $0.25/kWh. So it sounds like it's based on monthly net, but have not confirmed nor heard from someone in the same situation. I hope it's based on the monthly net consumption/production and not the instantaneous or hourly usage.
There will be a bidirectional meter for my main meter as well as a production meter only measuring solar production. As I understand it the production meter is for the SMART incentive.
