(4) Powerwalls with 8kw Solar Array cost concerns

[Vines]

Putting both sets of "Grid" CTs from two different Backup Gateway Neurio devices on the same main feed is obviously the wrong way to do it. You could have one set of CTs on the main feed and one on its own Gateway input like they place them at the factory. I see no reason that wouldn't work. It may not lead to equal loading and cycling on both sets of Powerwalls, but the customer should know that going in when they sign off on a parallel installation serving over 200A.

While I agree there are plenty of ways to make a system like this work well enough, there is enough confusion with these systems, that it may be a regulation thing, a training thing or a liability thing.

 

[miimura]

While I agree there are plenty of ways to make a system like this work well enough, there is enough confusion with these systems, that it may be a regulation thing, a training thing or a liability thing.

When it really comes down to it, if Tesla doesn't support it, then it shouldn't be done. However, that doesn't mean that someone who needs it shouldn't get a good reason why they don't support a certain configuration. That's where some of the problems are with Tesla Energy - Communication. It's hard to get answers from people who really know the right answers.

 

[tomguy]

While Powerwalls can limit the power they discharge, the NEC does not recognize that as an effective means to protect the busbar.

As to your question @tomguy It simply sounds like the Tesla team are in over their heads, or there was some confusion as to what panel was supposed to be installed. Pictures would help, and include the picture of the sticker, if you are comfortable with doing so, turn off power and remove the dead front and we can really see whats going on. I'm surprised after multiple site visits they didn't recognize that you had installed a main panel with distribution, rather than the Main breaker only panel, or a separate meter socket, that would have made this easiest. Now that things are sealed up under the stucco its tough to go and change things. Depending on the guts of the panel, there may be other options.

For those considering multiple backup systems in parallel @ohmman , Tesla may not allow that at all. They have told us that they do not want us to do this again, as it causes issues with the App, and the customer experience.

In the end, @Vines you are correct that Tesla was way over their heads on this. After they finally got back to me, they basically said the additional cost now is due to them having to subcontract out the electrical work because they didn't have the manpower to do the installation. So I told them, so it's somehow my fault now that Tesla was unable to deliver my referral powerwalls at the contract signing date last year, so now I have to end up paying over 5k more? They said there was no negotiation and I had them escalate it to upper management which they still hold to their price. So I ended having to sign the new contract with the much higher fee and within about a week I get a call from the electric subcontractor to schedule my installation of the main panel upgrade.

 

[RoBoRaT]

4 Powerwalls is large-scale storage, not small-scale. Tesla is not capped out on that program. Large-scale is currently on Step 2 for PG&E. See this page for details: https://www.selfgenca.com/home/program_metrics/

Per Tesla, they reached their limit on all Steps, seen here:

Powerwall and California SGIP | Tesla Support

"How much of a financial incentive will I receive for Powerwall?

Currently, Tesla has reached its cap for all steps, but some of our Certified Installers still have allocations for SGIP...."

I just recently receive a proposal and design from Tesla Energy for 10kW Solar PV system and 2 Powerwalls - but I declined it since Tesla can not submit application for SGIP, because of they reached their cap.
Both my Enrergy Advisor and Project Designer confirm SGIP will not be reserved for this project under Tesla.

It would be awesome if someone from Tesla Energy can confirm in writing that they will submit SGIP reservation for 4 Powerwalls for the OP. Otherwise, about $16K of SGIP rebate is on the line.

 

[Merrill]

At some point I believe Tesla will receive more funding from the 800m bill that was passed last August, there is now another 166m for 2019 for the SGIP program.

 

[tomguy]

Per Tesla, they reached their limit on all Steps, seen here:

Powerwall and California SGIP | Tesla Support

"How much of a financial incentive will I receive for Powerwall?

Currently, Tesla has reached its cap for all steps, but some of our Certified Installers still have allocations for SGIP...."

I just recently receive a proposal and design from Tesla Energy for 10kW Solar PV system and 2 Powerwalls - but I declined it since Tesla can not submit application for SGIP, because of they reached their cap.
Both my Enrergy Advisor and Project Designer confirm SGIP will not be reserved for this project under Tesla.

It would be awesome if someone from Tesla Energy can confirm in writing that they will submit SGIP reservation for 4 Powerwalls for the OP. Otherwise, about $16K of SGIP rebate is on the line.

I actually have 2 powerwalls under SGIP and 2 powerwalls under the referral program. The delay to install was due to the referral red powerwalls, otherwise I would've had this project completed early last year.

 

[SoundDaTrumpet]

Wayne is right on with the 705.12 and its various interpretations regarding sources vs loads.

If I wasn't going to do the service upgrade I'd leave the top breakers for the AC and pergola off the backup system and see if I could put the PV, and one or both of those subpanels in the backup circuit with a 125A max feed from that main panel. Depending on the load calculations between those 2 subpanels, a 125A breaker might be enough, and even if the load calcs are marginal, having 2 Powerwalls set to self consume will offset brief periods of what might have otherwise popped the 125A breaker in the main.

So you'd install a new Gateway and 200A subpanel next to the main off that 125A breaker, relocate all those subpanel feeds to that panel (or just choose to backup either garage or main house subs) and put the PV+PW in the same subpanel, though a separate generation panel is an option as well out of the 2nd lugs on the gateway.

Also, you can still self consume the AC loads even though they are not backed up and same with the garage or main subpanel. Just depends where and how many CT are installed, which determines where the TEG sees loads vs loads it cant see. Will still need a bit of stucco work but not the level of a new service panel.

@Vines @wwhitney Tesla came back and said my house panel exceeds 125A. Relocating breakers will trigger a redesign & reprice. I am considering going up in service rather than doing a 1:1 panel swap.

 

[Vines]

Sounds like a service upgrade or equipment swap is in order, if that is what they are recommending.

Increasing the service size to 400A is usually a big cost if the feed is underground. If its overhead it can be a lot cheaper. Still its cheapest just to swap equipment for something that works better with your system design.

 

[Lloyd]

In the end, @Vines you are correct that Tesla was way over their heads on this. After they finally got back to me, they basically said the additional cost now is due to them having to subcontract out the electrical work because they didn't have the manpower to do the installation. So I told them, so it's somehow my fault now that Tesla was unable to deliver my referral powerwalls at the contract signing date last year, so now I have to end up paying over 5k more? They said there was no negotiation and I had them escalate it to upper management which they still hold to their price. So I ended having to sign the new contract with the much higher fee and within about a week I get a call from the electric subcontractor to schedule my installation of the main panel upgrade.

Have an attorney send them a letter for non-performance of their original contract.

 

[SoundDaTrumpet]

Sounds like a service upgrade or equipment swap is in order, if that is what they are recommending.

The equipment swap is what Tesla is recommending. The engineer said a service upgrade must be driven by a need (e.g. adding a Tesla Wall Connector to force a service upgrade).

Increasing the service size to 400A is usually a big cost if the feed is underground. If its overhead it can be a lot cheaper. Still its cheapest just to swap equipment for something that works better with your system design.

I am crossing my fingers that the existing 3" conduit is free and clear when PG&E pulls a mandrel thru. If successful, the cost will just be slightly more than an overhead. It would be costly if the conduit is blocked and needs trenching to repair it.

If I decide to go with a slight service upgrade of 225A for an extra 25A, PG&E said would simply be a $70 charge for a meter pull. This has no forecasted cost risk because the service conductors will not need to be replaced going from 200A to 225A. The increased load will allow me to at least add another 50A for EV charging.

 

[SoundDaTrumpet]

@Vines @wwhitney Guys, thanks for all the help. Tesla was successful and designed a "no main breaker" solution to avoid a Main Panel Upgrade (MPU). I am backing up only the panel that powers the living space; thereby omitting EV charging and air conditioning. The gateway will sit behind a 125A branch breaker. I signed a new contract today to include the extra fee for hidden conduit. Everything should roll smoothly from here on out.

 

[NYUES88]

We have to do a MPU and sub upgrade as well as a new service mast and bonding. I am interesting in learning more about this 1900 that PGE gives back for a MPU. Do you know what the program is called and were you successful getting it?

Similar situation here. My PW + Solar is half of yours. I was originally quoted $0 and no need for a main panel upgrade (MPU). At the time the price was $2400 back in July 2017. Today the are saying I need the MPU because the combined 80A generation load from Powerwalls (2) and solar (4kW) exceeds the allowable backfeed of 40A on my main lug only (MLO) 200A main service panel. They are asking $3800 for this MPU line item.

Your situation sounds like a lessons learned walk-back from Tesla. I talked to the Tesla Electrical Engineer. / It sounds like you are a large user and most likely cannot simply swap main breakers either because your panel doesn't allow it, unavailable or not field replaceable (factory set), or because your loads are too high. They are pretty much putting in a 320/400A service upgrade. This is truly an upgrade not a replacement which the $2400 was. I asked specifically about what if I decided to add more solar or powerwall in way out in the future. It sounded like I would have to upgrade the upgrade. Not assuring to say the least.

I have PG&E rolling to do service upgrade on a different swim lane while Tesla is spinning. I objected to the new $3800 pricing and asked them to honor the prior pricing for MPU at the time of initial quote in 2017. Is this fair?

The $7875 does not shock me, but I would not be surprised if the $3800 current pricing is built into it. My contractor buddy said the prices are reasonable. PG&E supposedly pays back the homeowner up to ~$1900 for upgrades on the supply side as they really own anything leading up to the house. I would like to know is this being factored into the pricing. This gets the numbers to $5700 for you. Sounds like it's ~$2000 premium for 320/400A after all is said and done. Less $16000-$1800 for increased cost of the larger panel. The panel is double the width and is surface mount.

I appreciate the price you stated as it gives me a data point on what to expect for a service upgrade. What year/month was the quote made for the $2400? I saw this posted once before, but be good to have a contact.

 

[Vines]

@Vines @wwhitney Guys, thanks for all the help. Tesla was successful and designed a "no main breaker" solution to avoid a Main Panel Upgrade (MPU). I am backing up only the panel that powers the living space; thereby omitting EV charging and air conditioning. The gateway will sit behind a 125A branch breaker. I signed a new contract today to include the extra fee for hidden conduit. Everything should roll smoothly from here on out.

Sounds great. I have often said that "to make it safer, NEC says remove the Main Breaker!" Its a pretty silly interpretation of the code but at least it got you out of the problem!

We have to do a MPU and sub upgrade as well as a new service mast and bonding. I am interesting in learning more about this 1900 that PGE gives back for a MPU. Do you know what the program is called and were you successful getting it?

I believe this poster is referring to the PGE funds that pay for their portion of the service upgrade. Its a standard allotment for service side upgrades to your homes electrical service.

For instance, if you have an overhead drop and can get a new overhead drop as well that is the cheapest possible scenario, often the 1900 covers the PGE time and materials in entirety. These dollars are a credit to doing the wiring run, Meter etc.

Often times however you are in a location where a new 400A service cannot be an overhead aerial, and must be an underground service. This is usually a $20-30k cost, less the 1900 PGE gives you to do the upgrade.

 

[ReddykwRun]

Open question to the folks on this thread. Would you have gone solar if your grid power cost at the pole was .084 cents per kWh and no Net Metering? I live in Alabama, yea, I know it's worse than you think about being a non-friendly state towards solar. This month's power use was $95 for 1130 kWh of grid power. My ICF home does not use power but I wanted to see if it was financially viable for me to install a 9.26 kWh ground array (on 5 acres). A local contractor wanted to add two Tesla Powerwalls to the design for an extra $24,000. Gulp. I am strongly looking at installing my own system as a DIY project. Tesla does not service this backwoods area, the contractor would bring them from FL, I live ten miles across the state line into AL.

 

[mswlogo]

Open question to the folks on this thread. Would you have gone solar if your grid power cost at the pole was .084 cents per kWh and no Net Metering? I live in Alabama, yea, I know it's worse than you think about being a non-friendly state towards solar. This month's power use was $95 for 1130 kWh of grid power. My ICF home does not use power but I wanted to see if it was financially viable for me to install a 9.26 kWh ground array (on 5 acres). A local contractor wanted to add two Tesla Powerwalls to the design for an extra $24,000. Gulp. I am strongly looking at installing my own system as a DIY project. Tesla does not service this backwoods area, the contractor would bring them from FL, I live ten miles across the state line into AL.

Amortize the cost over 20 years (typically the warranty is 20 years on good panels).

The rule of thumb is, that solar cost around $0.08 per kWh when you amortize the cost.

 

[ReddykwRun]

Amortize the cost over 20 years (typically the warranty is 20 years on good panels).

The rule of thumb is, that solar cost around $0.08 per kWh when you amortize the cost.

So I see no gain of me going solar if it's the same cost of my grid power. Thanks.

 

[Akikiki]

Open question to the folks on this thread. Would you have gone solar if your grid power cost at the pole was .084 cents per kWh and no Net Metering? I live in Alabama, yea, I know it's worse than you think about being a non-friendly state towards solar. This month's power use was $95 for 1130 kWh of grid power. My ICF home does not use power but I wanted to see if it was financially viable for me to install a 9.26 kWh ground array (on 5 acres). A local contractor wanted to add two Tesla Powerwalls to the design for an extra $24,000. Gulp. I am strongly looking at installing my own system as a DIY project. Tesla does not service this backwoods area, the contractor would bring them from FL, I live ten miles across the state line into AL.

Wait a minute. I know you are under TVA, but you're paying less than 1/10 of a cent for one kwh?

 

[ReddykwRun]

Wait a minute. I know you are under TVA, but you're paying less than 1/10 of a cent for one kwh?

South Alabama, near the coast, Baldwin EMC is our Co-Op power provider. It's a 24/7 flat rate of .084 per kWh. Not quite 9 cents per kWh. .......... $95.00 / 1130 (kWh) = $ 00.084 per kWh.
I hear HI has some steep rates.

 

[Akikiki]

32-34 cents. You know though, that's different from what you said I first.

I grew up in North Bama.

 

[bob_p]

Open question to the folks on this thread. Would you have gone solar if your grid power cost at the pole was .084 cents per kWh and no Net Metering? I live in Alabama, yea, I know it's worse than you think about being a non-friendly state towards solar. This month's power use was $95 for 1130 kWh of grid power. My ICF home does not use power but I wanted to see if it was financially viable for me to install a 9.26 kWh ground array (on 5 acres). A local contractor wanted to add two Tesla Powerwalls to the design for an extra $24,000. Gulp. I am strongly looking at installing my own system as a DIY project. Tesla does not service this backwoods area, the contractor would bring them from FL, I live ten miles across the state line into AL.

We installed 44 330W panels (15.4 KW) and 4 PowerWalls at the end of December last year in Houston. Yesterday, for the last two days with full sun, our panels generated over 86 KWh of power, more than our house used.

Our current electricity plan is $.091/KWh (our previous plan was $.111/KWh).

Comparing the first 4 months of this year, our electric bills have dropped from $1336 (for Jan-Apr) to $403 - a $900 savings. Though not all of the savings was due to the solar power - because of the current crisis, we're not using as much electricity to charge our S & X vehicles.

When our current plan comes up for renewal, we may shift to a "free nights" plan that charges $.204/KWh from 9AM to 9PM with free electricity between 9PM and 9AM. Under that plan our electricity costs for Jan to Apr would have dropped to $194 (with all EV charging being done after 9PM each night).

At least so far, we are very satisfied with the cost savings we've seen from our solar panels/PowerWalls, even with the low electricity rates we're getting in Texas and no solar "buyback" (which isn't required in Texas). And if we really can use a "free nights" plan, we could drive our grid costs down even further.

NOTE that when we planned our system, we did a projection of when we would break even on the solar/PowerWall costs (after the 30% federal tax credit). For that assumption, we assumed an annual 3% increase in electricity costs. And based on those estimates, we projected break even after 11 years - which we decided was acceptable.

And based on results so far, we may have been too conservative in our estimates, and could see our break even point faster.

Plus, because we are getting about 2/3 of our electricity (on average) from our solar panels & PowerWalls, we're confident that we can operate off-grid for days during an extended power outage (hurricane) - saving us the cost of purchasing a backup generator (which might have cost us $10K, after installation).