Advice for installing storage system

[RKCRLR]

Thanks for the update. Hopefully you get yours installed before next Fall.

Thanks
My biggest concern is the Tesla bureaucracy. I put my Powerwall order in on April 14. I still haven't received answers to a bunch of questions or a design. They didn't seem familiar with the Equity Resiliency program until I pointed it out to them. I'm still not sure if they have actually submitted my incentive application, and they used their standard install price ($18,122.25) as the of incentive amount they requested vs the amount I qualify for ($26,400). I'm sure my install price is going to go up before the design is finished. Over a third of the funds were allocated yesterday (May 1) when PG&E opened up applications.
Trying to get Tesla to respond is an exercise in futility.

[Ampster]

Thanks for the update. Hopefully you get yours installed before next Fall.

[RKCRLR]

I thought I'd provide an update. I decided to go directly through Tesla since there is no developer cap for the SGIP Residential Equity Resiliency Program. If everything works out I will get 2 Powerwalls installed for free.

[Ampster]

........
He has shared many pros and cons of Powerwall that's why I find his videos informative. For me, energy sovereignty is a great goal but 6 Powerwalls with all the hassles he's gone through makes me wonder if it's really worthwhile. It does not seem that much simpler than soldering all the BMS wires for DIY battery packs.

Yes that is the conclusion I came to. Since each Powerwall contains its own inverter stacking multiple Powerwalls is not as cost effective as just adding battery capacity. With Powerwall stacking one might also be adding unneeded inverter capacity.

Since my original comment about his video I have watched a few more of his videos and I have more respect for his viewpoint than I initially mentioned. I made some comments on his blog and he was responsive. Thanks for that link.

[solardreamer]

...

The video above was a year old and the guy who posted the video has more recentlyunderstood how his Powerwall works and understands CA Rule 21 better now and no longer thinks it is a Investor Owned Utility conspiracy. He has become a real advocate for something that I believe in, which is the right to generate power and do anything behind the meter that you want to as long as it conforms to building codes. He calls it The Energy Sovereignty Project, It is a concept that most off gridders on this forum would agree with and he applies it to grid tied scenarios without relying on a generator,

I agree, I have watched many of this videos on the project. I think his point is that the federal tax credit requirement for only solar charging came from lobbyists working for utilities so they are ultimately responsible. He has shared many pros and cons of Powerwall that's why I find his videos informative. For me, energy sovereignty is a great goal but 6 Powerwalls with all the hassles he's gone through makes me wonder if it's really worthwhile. It does not seem that much simpler than soldering all the BMS wires for DIY battery packs.

[Ampster]

Your explanation is good but it also highlights just how complicated and unintuitive it is to get Powerwall with incentives.

The SGIP process is the same for any battery system that anyone wants to get incentives from. It is not just about Tesla. Actually Tesla ran out of the quota of SGIP incentives early on and if you look at the list of installers on the SGIP website most of them are third party installers. I spent a year working for a Congressman and I agree any governmental process can appear unintuitive, However if you start with the objectives of those incentives the logic becomes clearer, even if you disagree with the objectives and goals of the state of California. I cancelled my Powerwall order and did a self install of an Outback Skybox. I chose to take the Federal incentive but did not want to go through the controls imposed by the SGIP program for another 20 to 30% incentive. I also knew my used Nissan Leaf batteries would not qualify for the requirement for a 10 year warranty and I didn't want to pay the price for an LG Chem or SimpliPhi solution.

Also just wondering, does Tesla allow owners to opt out of their control of batteries if you agree to do your own tracking for audit purposes? It seems quite a few people are surprised to find they don't have full control of the Tesla batteries they own to use as they see fit. Perhaps Tesla does not explicit advertise you can charge from the grid but I don't think it's unreasonable for most people just looking for backup power solution to assume that since they charge lots of other batteries (e.g. laptops, rechargeable batteries, UPS, etc.) from the grid.

No, Tesla does not allow users to opt out. The only workaround would be to order a Powerwall when you have no solar, so you can charge from the grid. Then you would have to get a third party to install solar later but they would need to understand the Gateway to get the AC coupling to work with the new GT solar. Or if you are comfortable messing with CTs and understand how the Gateway logic works you could cobble together a workaround. I think that might mess with the warranty however. The Gateway is just a Neurio with several CTs connected to some logic. It is not to difficult to loop another wire through a CT or double the loop of an existing wire through a CT if you know what you are doing. If you have those skills a DIY hybrid system might be the most cost effective solution, That is what I chose to do and why I cancelled my Powerwall order. I am envious of the constant over the air updates that Powerwall users get and the knowledge base of users in California who understand how to best program their Powerwalls to leverage TOU rates and get a payback. There are that skeptics that don't think that is possible from a battery system.

Many people are surprised to find that their grid tie system doesn't work when the grid is down. I don't know who is responsible for peoples naivete. The value of forums like this is that those that choose to be informed and verify their assumptions have a better chance of making an informed decision. I don't think that is the fault of any particular solar installer when in a sales mode. Caveat Emptor has always worked for me.

I spend time on the Tesla Energy subforum of the Tesla Motors Club and most people there are well informed about the capabilities of the Powerwall system. I would disagree that many people are surprised about their Powerwalls. The workarounds I mentioned above came from that knowledge base. The video above was a year old and the guy who posted the video has more recentlyunderstood how his Powerwall works and understands CA Rule 21 better now and no longer thinks it is a Investor Owned Utility conspiracy. He has become a real advocate for something that I believe in, which is the right to generate power and do anything behind the meter that you want to as long as it conforms to building codes. He calls it The Energy Sovereignty Project, It is a concept that most off gridders on this forum would agree with and he applies it to grid tied scenarios without relying on a generator,

[solardreamer]

To be clear it is the Federal Tax credit that stipulates that you have to charge from the solar most of the time to get the credit. Tesla implements this by restricting the Powerwall so that Powerwall users do not have to produce documentation if they are audited, With my hybrid inverter I track the amount charged by solar in case I am audited because i took the Federat Tax credit. . Of interest to the OP, during inclement weather, Tesla can override those restrictions so that Powerwalls can be charged from the grid so that they enter those weather events fully charged. For example during last Fall in anticipation of the Public Safety power outages Tesla let affected users charge from the grid so that they when the power was turned off the Powerwalls would have a greater chance of being full. They did that with over the air controls. Other inverter manufacturers leave that up to the user. I don't know how Enphase will implement it. As far as SGIP incentive there is a monitoring that the specific utility does to make sure the user does not sell more to the grid than the expected output of their solar panel system. That is to prevent a user from charging from low cost power at night and selling back that power at high peak rates. That is part of what any user signs when he agrees to accept the SGIP incentive.


He makes a FALSE assumption that the control of this is with the Utilities because their plants will go idle. The reality of the deregulated California market is that the majority of generation capacity is in the control of independent generators like AES, CalAlpine and others who bought the generation assets twenty years ago. The control mechanism that video guy talks about is frequency of the grid not through the web connection. Incidentally that frequency is controlled by the California Independent System Operator (CAISO). Even old inverters had that ability to be shut down by a high frequency in the order of 61 or 62 Hz. That was necessary to protect the grid. That is what the OPs older inverter does and I assumed what he meant when he said, bang bang, is that those old inverters were either on or off. All Rule 21 did was force inverters to modulate. That is what the OP's Enphase IQ7's do. That reduces the shock to the grid and for a situation when the grid is down it is how AC coupling works. What that does is allow the Powerwall to leverage a GT system to generate power to charge the batteries and run the house load.

The video has a teaser headline because Tesla never advertised that you could charge from the grid if you had solar. Non solar customers who have Powerwalls can and do charge from the grid but they can not claim the Federal Tax incentive, They can apply for SGIP grants and in those cases, as noted above, those SGIP agreements restrict selling to the grid. The point of all post is that it is helpful to become informed because this is complicated and one could make assumptions that could turn out to not be as one thought they were causing a change in results that differ from expectations.

Your explanation is good but it also highlights just how complicated and unintuitive it is to get Powerwall with incentives. Also just wondering, does Tesla allow owners to opt out of their control of batteries if you agree to do your own tracking for audit purposes? It seems quite a few people are surprised to find they don't have full control of the Tesla batteries they own to use as they see fit. Perhaps Tesla does not explicit advertise you can charge from the grid but I don't think it's unreasonable for most people just looking for backup power solution to assume that since they charge lots of other batteries (e.g. laptops, rechargeable batteries, UPS, etc.) from the grid.

[Ampster]

Depending on the incentives you utilize you may not be able to use Powerwall like a regular battery/inverter system in many ways (e.g. charging from grid/generator as needed, etc.) that are important for backup power usage during outages especially extended ones.

To be clear it is the Federal Tax credit that stipulates that you have to charge from the solar most of the time to get the credit. Tesla implements this by restricting the Powerwall so that Powerwall users do not have to produce documentation if they are audited, With my hybrid inverter I track the amount charged by solar in case I am audited because i took the Federat Tax credit. . Of interest to the OP, during inclement weather, Tesla can override those restrictions so that Powerwalls can be charged from the grid so that they enter those weather events fully charged. For example during last Fall in anticipation of the Public Safety power outages Tesla let affected users charge from the grid so that they when the power was turned off the Powerwalls would have a greater chance of being full. They did that with over the air controls. Other inverter manufacturers leave that up to the user. I don't know how Enphase will implement it. As far as SGIP incentive there is a monitoring that the specific utility does to make sure the user does not sell more to the grid than the expected output of their solar panel system. That is to prevent a user from charging from low cost power at night and selling back that power at high peak rates. That is part of what any user signs when he agrees to accept the SGIP incentive.

I have found the experience of this owner of 6 Powerwalls very informative. It's way more complex than I had expected and seems more like a science project.
https://www.youtube.com/watch?v=2hYONZqkZcg

He makes a FALSE assumption that the control of this is with the Utilities because their plants will go idle. The reality of the deregulated California market is that the majority of generation capacity is in the control of independent generators like AES, CalAlpine and others who bought the generation assets twenty years ago. The control mechanism that video guy talks about is frequency of the grid not through the web connection. Incidentally that frequency is controlled by the California Independent System Operator (CAISO). Even old inverters had that ability to be shut down by a high frequency in the order of 61 or 62 Hz. That was necessary to protect the grid. That is what the OPs older inverter does and I assumed what he meant when he said, bang bang, is that those old inverters were either on or off. All Rule 21 did was force inverters to modulate. That is what the OP's Enphase IQ7's do. That reduces the shock to the grid and for a situation when the grid is down it is how AC coupling works. What that does is allow the Powerwall to leverage a GT system to generate power to charge the batteries and run the house load.

The video has a teaser headline because Tesla never advertised that you could charge from the grid if you had solar. Non solar customers who have Powerwalls can and do charge from the grid but they can not claim the Federal Tax incentive, They can apply for SGIP grants and in those cases, as noted above, those SGIP agreements restrict selling to the grid. The point of all post is that it is helpful to become informed because this is complicated and one could make assumptions that could turn out to not be as one thought they were causing a change in results that differ from expectations.

[Ampster]

..................
I think the 2 Powerwalls will be the cheapest initial solution since they will work with both the Enphase microinverters and my old string inverter (although not efficiently since it will be operating in bang-bang mode). But it would probably still be the cheapest even if I factor in a new string inverter.
The Enphase Encharge batteries don't appear to support anything other than Enphase IQ6/IQ7/ inverters so I would need to upgrade my old system to IQ7 microinverters, but my old string inverter is probably on borrowed time anyway. The nice thing about the Enphase Ensemble system is how well integrated it is. And the Enpower smart switch has generator input if they release the planned firmware (vaporware?) update. But it isn't clear to me if the generator input would recharge the batteries unless a "special" generator is used.
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A 4kW string inverter is $1,200 plus a few hundred for an electrician to swap it out. Micro inverters might be the same depending on how many panels you have but roof time labor is more expensive and to swap them out takes more time because each panel would have to be accessed from the rear.
I continually hear that the Powerwall is one of the best values out there for a turn key system. Since you already have a manual generator input you could always run the house loads off your generator and let the solar charge your batteries. My experience with Public Safety power outages is that they have occurred during sunny weather so the chances are that you will have solar during those times. That may be a better option instead of taking a chance that there will be vaporware or a special generator that can do that. Enphase is essentially AC coupled like the Powerwall and I don't know of any generators that have been successfully AC coupled. There are generators that use inverters to generate a cleaner sine wave, and all it would take is software for someone to come up with the control circuitry to fill that niche but it isn't even in the vaporware category yet.

[solardreamer]

It sounds like the incentives are the critical factor for your Powerwall decision to deal with PG&E PSP (i.e. mainly backup power during outages) so you should investigate and understand all the restrictions of Powerwall with various incentives. Depending on the incentives you utilize you may not be able to use Powerwall like a regular battery/inverter system in many ways (e.g. charging from grid/generator as needed, etc.) that are important for backup power usage during outages especially extended ones.

I have found the experience of this owner of 6 Powerwalls very informative. It's way more complex than I had expected and seems more like a science project.

https://www.youtube.com/watch?v=2hYONZqkZcg

[RKCRLR]

^^^^
I live in El Dorado county but thanks for the offer.
The Powerwall app has an option to send send you an alert when the grid goes down. I suspect Enphase will have something similar.
I think the limiting factor on how much rebate I can get will be based on the discharge rate. I get the feeling 2 Powerwalls (or equivalent) will be the sweet spot from the conversations I've had so far.
I think the 2 Powerwalls will be the cheapest initial solution since they will work with both the Enphase microinverters and my old string inverter (although not efficiently since it will be operating in bang-bang mode). But it would probably still be the cheapest even if I factor in a new string inverter.
The Enphase Encharge batteries don't appear to support anything other than Enphase IQ6/IQ7 inverters so I would need to upgrade my old system to IQ7 microinverters, but my old string inverter is probably on borrowed time anyway. The nice thing about the Enphase Ensemble system is how well integrated it is. And the Enpower smart switch has generator input if they release the planned firmware (vaporware?) update. But it isn't clear to me if the generator input would recharge the batteries unless a "special" generator is used.
Enphase seems big on powerline communication. I wouldn't be surprised if they introduced a smart transfer switch some time in the future that can be controlled by the Ensemble system.

Edit: I've found conflicting information that the residential “Equity Resiliency” storage rebate is limited to storage sizes of 10 kW or 10 kWh. I emailed PG&E for clarification (even their website doesn't state any size limit).

https://www.pge.com/en_US/residentia...r-process.page

[Ampster]

Okay then, I won't put any effort into figuring out a different solution. Where I was going with that is the possibility of derating your main house panel and pulling new conductors plus another set for a sub panel. I am not sure 2 1/2 conduit would have given you much flexibility anyway. The labor cost plus over 1,000 feet of wire was going to be expensive. That is a moot point now that you are comfortable manually controlling the loads. You could use the extra Cat 5 cable to send a control signal to some kind of bell or flashing light that would alert you when the grid drops so you can shut down any loads or at least be notified when the grid drops.

With regard to any Tesla Powerwall proposals, one caveat that I have heard through the grapevine is that Tesla Powerwalls are limited to 30 Amps each. That may mean that you might require 3 or 4 depending how they calculate that. However if you are going to be get a rebate at $1,000 per kWh of storage that extra storage might not cost you anything anyhow. I have pondered the 4 hour discharge test and I can understand how that might be a constraint but that would depend on all your loads running at once and might be worth verifying. There are probably some workarounds and it would be worth finding out which vendors are most familiar with those details. Interestingly, if you are in Sonoma or Mendocino counties, there may be a way to reduce the rebate risk if your vendors are not willing to guaranty the rebate. Let me know, and I can provide details. It is a non profit entity that provides gap financing.

Keep us informed as you progress through your decision process since this will be a good example for future readers to benefit from. This is especially true for readers in California because I think the state will continue to fund more SGIP rebates.

[RKCRLR]

The big unknown left to solve is the possible need for a sub panel and how to feed it, if it needs to be in the main house and on a separate separate feed from the battery backed inverter.
Do you know if the 200 Amp panel is fed through conduit or direct burial cable? If in conduit, what size is the conduit and conductors?

The PVC conduit is 2 1/2" OD. I don't know the size of the conductors but they are big. I don't feel like shutting the power down to measure and I don't like poking around in a live panel but I've included a picture (before the last solar install).

Having said that, both installers are proposing a "whole house" backup solution. I put "whole house" in quotes because the batteries won't actually be able to power everything in the house. Both have said that the systems will just shut down (like a power outage) if they detect an overload condition (and my research supports that), and I'm OK with that. I don't mind managing the loads manually.
20190607_113724.jpg

[Ampster]

The big unknown left to solve is the possible need for a sub panel and how to feed it, if it needs to be in the main house and on a separate separate feed from the battery backed inverter.
Do you know if the 200 Amp panel is fed through conduit or direct burial cable? If in conduit, what size is the conduit and conductors?

[RKCRLR]

^^^^
I'm in a Tier 2 moderate wildfire risk area and have PSPS shutdowns (way too many). I had looked into the SGIP rebates earlier but, like you, I determined I didn't meet the income eligibility requirements. But I guess a recent rule has been put in place that if you are on a well that relies on power from the grid then you don't need to meet the income eligibility requirements. I've been told this by two storage installers now.
My solar installer got back to me about how the rebate works. He said "it is $1,000 per kWh of storage. It is based on the amount of hours it takes to discharge. 2-4 hours gets 100%. 4-6 hours 50% and greater than 6 hours is 0%." I don't quite understand the discharge rate thing, it seems I'd be able to discharge any of the batteries in 4 hours.