Powerwall Site Inspection Tuesday

[Mayer]

After reading threads here on placement of Powerwalls, I wondered about the best location and how “stacking” is defined.

Can 3 Powerwalls be “stacked” like a deck of cards or must they be “stacked” side by side?

Garage is my preferred location but is it preferred/required to place Powerwalls next to main junction box, which is in our basement?

Main junction box is directly below garage. Might this make garage placement reasonably accessible?

Or is the focus more upon the location of my micro inverters which are outside near the garage?

Here are photos of exterior panels and basement panels:

 

[BGbreeder]

After reading threads here on placement of Powerwalls, I wondered about the best location and how “stacking” is defined.

Can 3 Powerwalls be “stacked” like a deck of cards or must they be “stacked” side by side?

Garage is my preferred location but is it preferred/required to place Powerwalls next to main junction box, which is in our basement?

Main junction box is directly below garage. Might this make garage placement reasonably accessible?

Or is the focus more upon the location of my micro inverters which are outside near the garage?

Here are photos of exterior panels and basement panels:

This is a call for your local AHJ, but in many places, the current code is that powerwalls need to be 36" from each other and from windows and doors into occupied spaces, and around here garage locations need impact protection for many places within the garage.

Personally, I think outdoors is the best location due to potential fire risk, especially if you don't live close to a municipal fire hydrant, and fire station.

All the best,

BG

 

[Mayer]

Thank you BG.
And I showed significant ignorance not understanding the micro inverters are under the panels. I was confusing the inverters with what must be other equipment (gateway) attached to the side of my home.

Anyway, it will be more than disappointing if 3 Powerwall batteries require 13.5’ of wall space (30” width x 3 + 36” spacing x 2) if my math is accurate. Even in my basement that will push it under the small window.

And outdoor placement with our side entrance garage and south facing patio in back, would place batteries on side of house furthest from main junction box requiring pass through finished portion of basement.

If you know, would SunVault’s system require less room?
I believe it uses refrigerator sized cabinets to store batteries so I’m guessing it might be a better fit?

 

[BGbreeder]

Thank you BG.
And I showed significant ignorance not understanding the micro inverters are under the panels. I was confusing the inverters with what must be other equipment (gateway) attached to the side of my home.

Anyway, it will be more than disappointing if 3 Powerwall batteries require 13.5’ of wall space (30” width x 3 + 36” spacing x 2) if my math is accurate. Even in my basement that will push it under the small window.

And outdoor placement with our side entrance garage and south facing patio in back, would place batteries on side of house furthest from main junction box requiring pass through finished portion of basement.

If you know, would SunVault’s system require less room?
I believe it uses refrigerator sized cabinets to store batteries so I’m guessing it might be a better fit?

I think that the wall space needed depends a little on where you start, but the Powerwall themselves are 3x30, plus 2x36 =162", so yes 13.5', but, the the ends of the three powerwalls would also need to be 36" away from doors or windows to occupied space.

I'm not sure how the basement window factors in, but if it opens to an "occupied" space, that would count, as far as I understand the code.

I'm not an expert, but I believe that installations in a basement itself carry other requirements, like fire resistant ceilings to a certain level and volume requirements.

I don't know the sunvault system, so I would only be guessing.

All the best,

BG

 

[Matt-FL]

It depends on local codes. Mine were installed last year (in Florida) in my garage. They are double-stacked with about a foot in-between each stack. I did install a smoke detector on the ceiling above, but I also have temp sensors that will notify me if the temps get above what is normal - hopefully long before any fire hazard. I'm not very concerned about a fire hazard. If there was one, I'm in a ranch style home and can easily (grab the cat and) exit if needed.

For the past year they have been keeping in a very solid temp range, and I personally prefer them installed in my garage rather than baking in the hot sun and Florida humidity. I expect them to have a longer lifespan in a more controlled temperature environment.

 

[Mayer]

It depends on local codes. Mine were installed last year (in Florida) in my garage. They are double-stacked with about a foot in-between each stack. I did install a smoke detector on the ceiling above, but I also have temp sensors that will notify me if the temps get above what is normal - hopefully long before any fire hazard. I'm not very concerned about a fire hazard. If there was one, I'm in a ranch style home and can easily (grab the cat and) exit if needed.

For the past year they have been keeping in a very solid temp range, and I personally prefer them installed in my garage rather than baking in the hot sun and Florida humidity. I expect them to have a longer lifespan in a more controlled temperature environment.

Thank you Matt.
I wonder if reliable data exists on prevalence of fires.
I suppose an equal or greater problem is the fire starting elsewhere and the Powerwalls igniting.
Maybe I’ll talk to my insurance agent too.
I hate insurers but the know risk.

 

[BGbreeder]

Again, home electrical storage systems are bleeding edge technologies in my view. I expect bleeding edge technologies to fail more often than "normal" things.

One of the prime reasons that I bought Tesla Powerwalls over other brands is that the battery pack and technology come out of their vehicles. That gives me a warm fuzzy in the high MTBF over millions of vehicle miles, and the high probability that reliability transfers to the Powerwalls. The inverter/charger technology is quite old. If a capacitor blows in the AC system, it may take the battery system down, but it is highly unlikely to ignite a metal encased battery pack. The bit to keep your eye on is the battery in my view.

Cars can have 10X the capacity of a Powerwall, so you get to very high numbers of cycles/pack/year quickly. That means the estimate of MTBF has some good statistics on it, not just someone running a spreadsheet on a few early prototype battery packs.

There are elements of other systems that I like, but I like to look at the warranty. Is it 25 years? 20? 10? 5? That gives you the purchaser some insights as to what the company thinks. I went with Enphase microinverters for similar reasons.

By all means try a different vendor and technology, but I would do so with the understanding that what you are buying into is not as well tested, even if the underlying battery chemistry is thought to be safer. Manufacturing process is a big deal for battery safety and reliability. Sony had a billion, that is with a B, dollar recall on batteries due to a tiny manufacturing process alteration that allowed minute metal shavings to occasionally drop into battery cells. Getting precision, reliability, and scale in electrochemical production is incredibly hard to do at any scale, but especially at large scale.

I would suggest that you consider looking at a few videos of battery fires (e.g. this one)

and then think about whether you want that much energy inside your house.

One of the installers here, @Vines, posted some great photos of batteries on a freestanding wall behind some roses.

All the best,

BG

 

[Mayer]

I haven’t watched entire video yet (saw fireman slowly engaging) but instead went down this rabbit hole first:

Does Powerwall have a UL 9450A test report?​

Despite the alarms this thread raised (or referenced), or because of the alarms it raised, it was well worth the read.

Thank you @BGbreeder for pointing in that direction, and thank you @Vines for the details and closing concern about updated UL 9450A testing compliance.

And to think, when I started this journey I wanted to place my PWs in my family room as artistic display if only my wife would permit. I never realized I might have to also convince the Fire Marshal and municipality to “permit” it too.

I might plant another rose garden instead.

On the other hand, I do not live in wildfire country (although there are no fire hydrants within miles either).

Maybe I put this project on hold until I can build the detached garage I’ve always wanted, and use it to house the batteries and support a few more solar panels too.

That sounds better than a rose garden.

Thank you again, and I agree, when it comes to battery tech, Tesla is running away with the prize, exponentially.

 

[Mayer]

Site inspection went well.
It was a Tesla employee; I was expecting a local contractor.
He felt batteries could be stacked and placed in garage; he did not expect a problem from our township here in Pennsylvania with stacking but said placement in garage must be in side wall rather than back wall or bollard would be required to protect battery from car driving into battery.
He did advise Tesla’s online pricing (2 PWs for $24,486 & 3 PWs for $33,072) is for exterior install near meter and additional fees would be added for interior/garage install but proposal would have both options.
He looked over panels in basement and wall charger in garage, took photos and measurements, flew drone over our roof/array and was gone in under two hours, much of which was filled with conversation.

He said he didn’t expect a backorder delay on PW2, mentioned $500 panel discount but had no info on pending release of PW3 beyond that, given $500 discount through 10/31, it is anticipated to be available “soon.”

 

[Matt-FL]

Another aspect to consider is where on the outside of your house the batteries will be placed. Attached to the side of your house means a fire hazard just as much as being inside your garage. In my case, the batteries would have been placed next to the meter and inverters/gateway which is on the side of a bedroom. Our garage is the furthest point away from the bedrooms, so it ticked several of my requirements checkboxes.

 

[Mayer]

Another aspect to consider is where on the outside of your house the batteries will be placed. Attached to the side of your house means a fire hazard just as much as being inside your garage. In my case, the batteries would have been placed next to the meter and inverters/gateway which is on the side of a bedroom. Our garage is the furthest point away from the bedrooms, so it ticked several of my requirements checkboxes.

Agreed. I’ve been thinking out outside location and wondered cost of pedestal adjacent to my AC compressor, meter, gateway ….

If hung on stucco exterior is still a fire risk and kind of in a “drive lane,” next to where we park daily (outside our garage), although not like the drive lane in a garage.

I am assuming that in the event of battery meltdown the heat initially comes from sides, top, and bottom of the battery, but eventually would likely ignite anything close to those flames/heat.

I’m not even sure there’s room near my meter for a pedestal installation, and the side of the house might be the only option given the window and door.

Any thoughts on the attached photograph?

 

[Mayer]

Better pics attached.
I’m leaning toward pedestal at location of the hydrangea. It does get morning sun, but is shaded from afternoon sun.
I wonder if pedestal installation permits stacking two power walls together?

 

[Matt-FL]

If you want to put it to the left of the heat pump, Tesla will (most likely) have you remove the bushes in front of it. In my original design with powerwalls outside, they asked me to remove all bushes within a 4' area of the location, with adequate entry and exit points.

The weight of the unit is the ground, the wall mount is just to hold it up. If it goes out there, you might want to get a concrete pad or something for it to sit on. That would also protect it from rain-dirt splashing up on the pretty glass enclosures

 

[BGbreeder]

Don't forget the 36" away from windows rule...

I would also put in a concrete pad. The powerwalls are technically electrical equipment and clearance rules apply.

 

[Vines]

Don't forget the 36" away from windows rule...

I would also put in a concrete pad. The powerwalls are technically electrical equipment and clearance rules apply.

The Powerwalls are probably not required to follow normal working space clearances, this somewhat depends on your location, AHJ and inspector.

Personally, I would put my units on the exterior wall 3' away from the window, and 18" from the condenser if possible. As an alternative, you could free stand them on a concrete pad away from the home slightly.

 

[Mayer]

Thank you all for the feedback, experience, and expertise.
I had not thought about a concrete pad but it makes sense.