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Mass Save Connected Solutions Incentive

EdA

Model S P-2540
Mar 24, 2011
2,306
262
Cape Cod
I don't understand how the utilities don't just install a few MW of batteries. Why is a distributed system better?
 

Retrospected

Member
Sep 29, 2017
128
52
New Hampshire
"Which Batteries Qualify?
National Grid Customers: The battery storage systems supported by this program are:

Pika Energy Harbor Smart Plus & Flex
SolarEdge
Sonnen
Sunrun BrightBox
Tesla Powerwall

Eversource Customers: Please contact Eversource to determine what battery storage systems are supported.

Customers are eligible to apply for a HEAT loan for the material and labor costs associated with installing a battery storage system to participate in ConnectedSolutions. The HEAT Loan cannot be used to cover the cost of the solar PV or the cost to use setup your battery system for backup power. If you are interested in receiving an authorization form which can be brought to participating lenders to apply for a HEAT Loan, please mark the appropriate field on your ConnectedSolutions application. Please consult your battery vendor for more details."

In the application:
"0% Financing for the cost of the battery is available through the HEAT Loan. QUALIFIED customers MAY receive an Authorization Form which can be brought to Participating Lenders to apply for the loan. Some restrictions apply, see MassSave.com/HEATLoan for eligibility requirements and details."

and lastly Masssave website..
To be eligible:
  • You must have completed a Mass Save Home Energy Assessment
  • You must have a residential electric account with one of the participating sponsors, National Grid and Eversource
    Note: If you live in a municipal town, you must heat your home with National Grid or Eversource Gas (not eligible for electric cooling measures)
 

Tdreamer

Supercharger
Supporting Member
Sep 10, 2017
1,270
2,294
Bedford, Massachusetts
Update on this - I reached out to Eversource the other day and they confirmed Tesla Powerwall support was just added. They will begin accepting applications for them March 1st, 2020.
 
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canbonbon

Member
Nov 12, 2017
92
81
Boston
If a home already has Solar panels on the roof and are part of the Netmetering program, then how does having these batteries help them? Whatever they generate builds credit that is used up at night or in months they are not producing enough. I cannot think of any advantages of a battery except on those days when you loose power? So in short, they will replace a generator. But in states where Net metering is not offered this could be a viable option. Can someone enlighten me on this? Maybe I am surely missing something considering there is so much excitement about Powerwalls.
 

tga

Supporting Member
Supporting Member
Apr 8, 2014
3,997
2,865
New Hampshire
I don't understand how the utilities don't just install a few MW of batteries. Why is a distributed system better?
The goal of this program (and the similar program in NH under Liberty Utilities) is to reduce peak demand charges at the wholesale meter (between the transmission grid and the substations) by discharging batteries to meet some of the retail demand during the ~3 hour monthly ISO-NE peaks. Transmission charges are prorated and based on the utility's peak demand during these peaks. If you can reduce demand during these peaks, you can reduce overall transmission costs, which, in turn, reduces costs for all ratepayers. To do this, you need to put the batteries on the retail/distribution side of the wholesale meter (ie, in the substation or closer to the end user). A large bank of Powerpaks at the substation or lots of Powerwalls at the end users both work.

One advantage of a distributed network of smaller batteries (ie, Powerwalls) is that, by distributing the storage closer to the end users, you reduce load on the distribution grid, potentially reducing the need to upgrade wiring, transformers, etc in your distribution grid (utilities call these kinds of projects a "non-wires alternative", or NWA). The distributed model is also more efficient, since there's less power wasted as heat pushing the batteries' power through a network of wires and transformers.

If a home already has Solar panels on the roof and are part of the Netmetering program, then how does having these batteries help them? Whatever they generate builds credit that is used up at night or in months they are not producing enough. I cannot think of any advantages of a battery except on those days when you loose power? So in short, they will replace a generator. But in states where Net metering is not offered this could be a viable option. Can someone enlighten me on this? Maybe I am surely missing something considering there is so much excitement about Powerwalls.
If you have net metering, there isn't much of an advantage to a powerwall on its own; it really just becomes an expensive, quiet generator (with a limited fuel supply). You need time of use rates (where retail rates are higher when wholesale rates are higher), or incentive payments for allowing the utility to tap into your battery for the finances to work out. The former (TOU rates) are common in CA. The Eversource program discussed in the OP is an example of the later. The utility is sharing some of the cost savings in avoided transmission costs with the owners of the batteries.
 

canbonbon

Member
Nov 12, 2017
92
81
Boston
Thanks that was informative. Tried to read the description and checked the prices for Tesla Powerwall. So it will cost about $14000 to install two Tesla powerwalls. From what I could read the connected solutions incentive for National Grid (probably same for Eversource) is about $1000 a year (not guaranteed) if you participate in that program and have solar. So it will take about 14 years to get the return. From what I know if the Tesla Powerwall is not installed with Solar, then you cannot claim Federal credit. Are there any other credits for install Powerwall?
 

brianbsl

Member
Feb 13, 2019
35
37
Southborough, MA
I had 2 Powerwall's installed under this program last summer, we are in National Grid territory, its the same program basically but started earlier. We had a somewhat complex install due to our panel configuration and found it less expensive to use MassRenewables for it and they were also more responsive.

On two Powerwall's you should do much better than $1000/yr (Tesla estimates $700/yr per Powerwall, so $1400 would be their estimate on 2).. The summer payment is $180/kW average during the event and the winter is $40. So total of $220. All events so far have been 2 hours. They are allowed to call 3 hour events but there have not been any. For a 2 hour event, two Powerwall's can discharge at 10kW for the entire event, so if they stay as 2 hour events, that is $2200/yr, if they mix in some 3hrs call it $1500/yr. On an event day, the Powerwall charges multiple times a day (whereas on a standard day, it only charges up once per day), so its always at 100% when the event starts. On my first event I only averaged 9.3kW as it seemed to aim to leave some reserve (20%?), after that I turned off Storm Watch and have been getting 10kW for the full event (not sure if it was the storm watch change or a Tesla change) and then end the day at about 15% remaining.

I have not received my payment yet for last summer. With Tesla, you do not get paid directly, the utility pays Tesla and then Tesla pays you after taking a cut (20%) for running the program. Has anyone else gotten a payment yet? The Tesla guys at the email address are somewhat responsive (in that they respond to about half the emails I send them) and my understanding is there were some delays, but hoping to get the summer 2019 payment in the next few weeks.
 

jsurpless

Member
Feb 20, 2020
99
9
Massachusetts
On two Powerwall's you should do much better than $1000/yr (Tesla estimates $700/yr per Powerwall, so $1400 would be their estimate on 2).. The summer payment is $180/kW average during the event and the winter is $40. So total of $220. All events so far have been 2 hours. They are allowed to call 3 hour events but there have not been any. For a 2 hour event, two Powerwall's can discharge at 10kW for the entire event, so if they stay as 2 hour events, that is $2200/yr, if they mix in some 3hrs call it $1500/yr. On an event day, the Powerwall charges multiple times a day (whereas on a standard day, it only charges up once per day), so its always at 100% when the event starts. On my first event I only averaged 9.3kW as it seemed to aim to leave some reserve (20%?), after that I turned off Storm Watch and have been getting 10kW for the full event (not sure if it was the storm watch change or a Tesla change) and then end the day at about 15% remaining.

I have not received my payment yet for last summer. With Tesla, you do not get paid directly, the utility pays Tesla and then Tesla pays you after taking a cut (20%) for running the program. Has anyone else gotten a payment yet? The Tesla guys at the email address are somewhat responsive (in that they respond to about half the emails I send them) and my understanding is there were some delays, but hoping to get the summer 2019 payment in the next few weeks.

Hi Brian

My mom is considering a similar install to what you have and had some questions.

Could you elaborate on why you say that the summer rate is $180/kw and the winter rate is $40/kw when MassSave says that it's $225/kw and $50/kw, respectively?

Regarding the difference between a 2-hr and 3-hr event incentive rate, I take it that a battery can't charge and discharge at the same time? I thought that I had asked Tesla about not being able to sustain the full 5kw discharge rate for a 3-hr event and asked if her solar system could make up for that by charging the battery while it was being discharged. I guess I was mistaken?

Regarding the discharge rate - what determines this? Is it just based on what you can provide (i.e, they take whatever you can/willing to give them)? Or does the utility decide?

Tesla takes a cut of the incentive? I haven't seen any mention of that?

Thanks!
 

brianbsl

Member
Feb 13, 2019
35
37
Southborough, MA
Hi Brian

My mom is considering a similar install to what you have and had some questions.

Could you elaborate on why you say that the summer rate is $180/kw and the winter rate is $40/kw when MassSave says that it's $225/kw and $50/kw, respectively?
This answers your last question as well, but it's because Tesla is taking a 20% cut here. When you fill out the program application with Tesla you have to choose to have them send the incentive to Tesla. So your utility will send the $225/$50 to Tesla, but Telsa only then sends you $180/$40 (in theory, although they have not yet but are responsive when I ask for the status). They say this is to cover the costs of running the program. Its annoying, but in their defense:
  1. At this small scale, I really do thing they are at best breaking even on the costs of running this. I think there are 1-2 people at Tesla who work on this close to full time, but only in the low hundreds of households enrolled. So optimistically they would decrease this cut as the program scales, but that also seems unlikely.
  2. Powerwall is still much better break-even than any other battery solution on the market (most kWh/$), much more than 20% better.
  3. If you are participating in SMART also, the way the DC-attached battery solutions work (SolarEdge, Sunrun which is still SolarEdge, and Pika), you end up not earning SMART generation credits for those kWh (unless they have fixed this) because the gen credits are done using an AC meter provided by the utility which is after the entire DC plant.
  4. I believe Sunrun is doing it where the end user doesn't get any of the credits and it's all "baked in" on the Sunrun lease/PPA.
Regarding the difference between a 2-hr and 3-hr event incentive rate, I take it that a battery can't charge and discharge at the same time? I thought that I had asked Tesla about not being able to sustain the full 5kw discharge rate for a 3-hr event and asked if her solar system could make up for that by charging the battery while it was being discharged. I guess I was mistaken?
It can charge and discharge at the same time during outage events (well really it either charges or discharges and is offset by the solar - as in if your solar generation exceeds the demand of the house, it will charge, if it does not, it is discharging but at a lower rate - note there is actually a 3rd state where your solar generation exceeds the demand of the house, and the battery is either fully charged or your generation exceeds the charging capacity of the power-wall, in that case the Powerwall signals to the solar inverter via a frequency shift to shutdown the inverters.
Anyways, during one of these events, since its not an outage, you export both your PV and your Powerwall discharge, so any PV generation does not count towards the event discharge, and is not stored in the Powerwall. Originally when this program was drafted they were going to include PV generation during events, but the final program did not, I'm not sure if that was for technical or economic reasons.

Regarding the discharge rate - what determines this? Is it just based on what you can provide (i.e, they take whatever you can/willing to give them)? Or does the utility decide?
I think it gives everything it can give, but calculated to attempt to be even across the event. So if its a 3hr event, I would expect to see 8.6kW discharge on 2 Powerwall's with Storm Watch disabled (which seems to preserve 20%) and 6.9kW discharge with Storm Watch enabled. But we have not seen any 3 hour events yet, so I don't have any data. (I export the csv out of the Tesla app for every day there is an event for my own records)

One final note - I think this is only worth it if you really want the backup (and the backup's value is somewhat questionable in the winter where we often have days that you would not be able to recharge, although if you are using fossil fuel for heating, perhaps your consumption is low enough), OR if you are also participating in SMART and get the storage incentive.
 

tga

Supporting Member
Supporting Member
Apr 8, 2014
3,997
2,865
New Hampshire
note there is actually a 3rd state where your solar generation exceeds the demand of the house, and the battery is either fully charged or your generation exceeds the charging capacity of the power-wall, in that case the Powerwall signals to the solar inverter via a frequency shift to shutdown the inverters.
Why? This is just wasting solar generation capacity instead of exporting it to the grid. I hope they don't try to do this in the Liberty Utilities NH program.
 

jsurpless

Member
Feb 20, 2020
99
9
Massachusetts
This answers your last question as well, but it's because Tesla is taking a 20% cut here. When you fill out the program application with Tesla you have to choose to have them send the incentive to Tesla. So your utility will send the $225/$50 to Tesla, but Telsa only then sends you $180/$40 (in theory, although they have not yet but are responsive when I ask for the status). They say this is to cover the costs of running the program. Its annoying, but in their defense:
  1. At this small scale, I really do thing they are at best breaking even on the costs of running this. I think there are 1-2 people at Tesla who work on this close to full time, but only in the low hundreds of households enrolled. So optimistically they would decrease this cut as the program scales, but that also seems unlikely.
  2. Powerwall is still much better break-even than any other battery solution on the market (most kWh/$), much more than 20% better.
  3. If you are participating in SMART also, the way the DC-attached battery solutions work (SolarEdge, Sunrun which is still SolarEdge, and Pika), you end up not earning SMART generation credits for those kWh (unless they have fixed this) because the gen credits are done using an AC meter provided by the utility which is after the entire DC plant.
  4. I believe Sunrun is doing it where the end user doesn't get any of the credits and it's all "baked in" on the Sunrun lease/PPA.
To clarify, your #3 point doesn't apply to Tesla? So we could participate in SMART battery adder?

It can charge and discharge at the same time during outage events (well really it either charges or discharges and is offset by the solar - as in if your solar generation exceeds the demand of the house, it will charge, if it does not, it is discharging but at a lower rate - note there is actually a 3rd state where your solar generation exceeds the demand of the house, and the battery is either fully charged or your generation exceeds the charging capacity of the power-wall, in that case the Powerwall signals to the solar inverter via a frequency shift to shutdown the inverters.
Anyways, during one of these events, since its not an outage, you export both your PV and your Powerwall discharge, so any PV generation does not count towards the event discharge, and is not stored in the Powerwall. Originally when this program was drafted they were going to include PV generation during events, but the final program did not, I'm not sure if that was for technical or economic reasons.

This actually brings up another question - during an outage, say a bright and sunny day with excellent PV production. What would the solar panels be doing when the battery is full and my generation exceeds the house load? I would like the house load to not come from the battery but I'm not sure that's what happens? Mainly because if I'm generating 40kw and only using 20kw, there's nowhere for that extra 20kw to go? Does the solar system get turned off OR does it "scale down" in some fashion via this frequency shift you mentioned?

Regarding a 3-hr event at 5kw average rate - I know the battery can sustain that full rate for 13.5 kWh / 5k = 2.7 hrs which wouldn't be an average of 5kw for the entire event. Could some of my generation go into the battery while it's discharging to supplement that 13.5kWh as it's being depleted so that it could supply the 5kw for the entire 3 hrs? Kind of like simultaneously filling a tank while drawing from it?

I think it gives everything it can give, but calculated to attempt to be even across the event. So if its a 3hr event, I would expect to see 8.6kW discharge on 2 Powerwall's with Storm Watch disabled (which seems to preserve 20%) and 6.9kW discharge with Storm Watch enabled. But we have not seen any 3 hour events yet, so I don't have any data. (I export the csv out of the Tesla app for every day there is an event for my own records)

One final note - I think this is only worth it if you really want the backup (and the backup's value is somewhat questionable in the winter where we often have days that you would not be able to recharge, although if you are using fossil fuel for heating, perhaps your consumption is low enough), OR if you are also participating in SMART and get the storage incentive.

I assume that the 8.6kW discharge you mentioned is the PowerWall determining that it can do 27kWh evenly over the 3 hrs?

As for this making financial sense, I realize that this is unlikely to "make money" - my mom heats with oil but has a sump pump in her basement which is why she's drawn to the battery security.

Thanks!
 

brianbsl

Member
Feb 13, 2019
35
37
Southborough, MA
Why? This is just wasting solar generation capacity instead of exporting it to the grid. I hope they don't try to do this in the Liberty Utilities NH program.
This state is during an outage, not during a discharge event. During an outage, you are disconnected from the grid, so there is no place to export it. See further down in my message for the behavior during a discharge ("Grid Services") event, it does go to the grid, in MA at least, you do not get paid for your PV export, only the battery discharge (regardless of export, discharge + self consumption is still paid).
 

brianbsl

Member
Feb 13, 2019
35
37
Southborough, MA
To clarify, your #3 point doesn't apply to Tesla? So we could participate in SMART battery adder?
Correct PowerWall is an AC connected system, even if you do Tesla Solar (usually with a SolarEdge string inverter with optimizers), so that point does not apply. On a SMART (not SREC) PV install, the Solar inverter AC power will go through the AC generation meter before connecting to the PowerWall gateway.

This actually brings up another question - during an outage, say a bright and sunny day with excellent PV production. What would the solar panels be doing when the battery is full and my generation exceeds the house load? I would like the house load to not come from the battery but I'm not sure that's what happens? Mainly because if I'm generating 40kw and only using 20kw, there's nowhere for that extra 20kw to go? Does the solar system get turned off OR does it "scale down" in some fashion via this frequency shift you mentioned?
I have not seen it happen because my only outages with Powerwall so far have been short overnight ones but I believe it will cycle your solar back and forth - as in shut it down, let it discharge a bit, then turn it back on to recharge to 100% etc. I have a microinverter system where that could theoretically be possible but that would have to be over Enphase's PLC protocol not over the frequency shift, I believe the frequency shift signaling is all or nothing but I have not read the specs on it.

Regarding a 3-hr event at 5kw average rate - I know the battery can sustain that full rate for 13.5 kWh / 5k = 2.7 hrs which wouldn't be an average of 5kw for the entire event. Could some of my generation go into the battery while it's discharging to supplement that 13.5kWh as it's being depleted so that it could supply the 5kw for the entire 3 hrs? Kind of like simultaneously filling a tank while drawing from it?
No because during a discharge event your generation goes to the grid not to the battery. The battery is either charging or discharging, so what you are really asking for is for your PV export to count, which it does not under the final version of this program.
Anyways like I said every single event so far has only been 2 hours.

I assume that the 8.6kW discharge you mentioned is the PowerWall determining that it can do 27kWh evenly over the 3 hrs?
Yes, thats the capacity of 2 Powerwall's from 100% to 0%.

As for this making financial sense, I realize that this is unlikely to "make money" - my mom heats with oil but has a sump pump in her basement which is why she's drawn to the battery security.

Thanks!
If this is really what you are trying to deal with (sump pump), just buy a battery backup sump pump system. I had one from Wayne in my old house. It uses a marine battery, or you could get fancier telecom batteries if you wanted. This goes in parallel with your existing pump through some check valves with the DC pump setup to trigger at a higher level. I would imagine you could be all-in installed for like $1k and DIY for like $500.
 

tga

Supporting Member
Supporting Member
Apr 8, 2014
3,997
2,865
New Hampshire
This state is during an outage, not during a discharge event.
Got it. I missed that point.
in MA at least, you do not get paid for your PV export
Do you no longer get net metering credit though?
If this is really what you are trying to deal with (sump pump), just buy a battery backup sump pump system. I had one from Wayne in my old house. It uses a marine battery, or you could get fancier telecom batteries if you wanted. This goes in parallel with your existing pump through some check valves with the DC pump setup to trigger at a higher level. I would imagine you could be all-in installed for like $1k and DIY for like $500.
I did a DIY battery backed sump pump once just like that - a marine bilge pump, installed above the main sump pump trip height, with a 12V deep cycle and float charger to power it. I ran an extra exhaust line, so no issues with check valves. Easy-peasy.
 
Last edited:

brianbsl

Member
Feb 13, 2019
35
37
Southborough, MA
Do you no longer get net metering credit though?
You still get net metering credit, it just does not count towards the discharge incentive. How this works with the battery is basically you get your generation (SMART/SREC) credits immediately. You get your net metering credits when you discharge. So you are always sitting on 26kWh of net metering credits (PLUS the loss of keeping the battery topped off, which seems to be about 0.6kWh/day) in your battery when its at 100%.
The top-off loss is annoying but works out to about $50/yr of net metering credit loss, plus the $6 of credit always stuck in the battery.
 

jsurpless

Member
Feb 20, 2020
99
9
Massachusetts
So you are always sitting on 26kWh of net metering credits (PLUS the loss of keeping the battery topped off, which seems to be about 0.6kWh/day) in your battery when its at 100%.
The top-off loss is annoying but works out to about $50/yr of net metering credit loss, plus the $6 of credit always stuck in the battery.

I'm not familiar with the Tesla app so maybe this is clear within it but how do you estimate that there's a "top-off" cost to the battery?

If this is really what you are trying to deal with (sump pump), just buy a battery backup sump pump system. I had one from Wayne in my old house. It uses a marine battery, or you could get fancier telecom batteries if you wanted. This goes in parallel with your existing pump through some check valves with the DC pump setup to trigger at a higher level. I would imagine you could be all-in installed for like $1k and DIY for like $500.

It's not all that she's trying to deal with (fridge back and heat is a priority as well), it's just that her basement flooded several years back so the sump pump is important as well.
 

brianbsl

Member
Feb 13, 2019
35
37
Southborough, MA
I'm not familiar with the Tesla app so maybe this is clear within it but how do you estimate that there's a "top-off" cost to the battery?
Yes, you can both export a CSV and inside the app see a graph and sum for each source/destination. So if I go to yesterday, and choose to graph only Powerwall data, it shows me 0.6kWh. Its one of the more well-done solar app implementations (better than Enphase or SolarEdge's app's) but its app-only, no website access, and I don't think they ever show you any per-panel data even if you have Tesla solar with SolarEdge optimizers. You do get solar data even if you add Powerwall to an existing solar install.
 

jsurpless

Member
Feb 20, 2020
99
9
Massachusetts
Update on this - I reached out to Eversource the other day and they confirmed Tesla Powerwall support was just added. They will begin accepting applications for them March 1st, 2020.

TDreamer - I was just told by Tesla that they're not currently participating with EverSource but are working on it. How did you contact EverSource (I tried calling but got nowhere with anyone knowing anything about the program and was told to email).
 

Tdreamer

Supercharger
Supporting Member
Sep 10, 2017
1,270
2,294
Bedford, Massachusetts
TDreamer - I was just told by Tesla that they're not currently participating with EverSource but are working on it. How did you contact EverSource (I tried calling but got nowhere with anyone knowing anything about the program and was told to email).
I believe I submitted an inquiry via a web contact form on the connected solutions website. I got an e-mail response from them within a day or two stating they would begin accepting applications on March 1st, and the applications would be collected by Tesla. They stated they would have a link to the application closer to the start date. I've not yet had any further contact from them. PM me for the contact info if you like. I'll gladly share the link to the application if/when I receive it. I have my site survey later this week by Tesla Energy and hopefully will learn more at that time.
 

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