Powerwall 2 Design

[gpez]

Maybe I'm putting too much value on the simplicity (design-wise) of a whole-home backup. Maybe it's easier than I imagine to convert my existing main panel (brand new) to a main panel + essential loads panel. Will a lot of electrical work be 'undone' from my existing main panel if I end up just installing a single PowerWall and need to add an essential loads panel to limit backup to lights and outlets? How hard is the wiring for a partial home backup vs a whole home backup?

My utility also pays 1:1 for supplying the grid so I don't need the battery to time-shift my solar usage....

Our solar + PW was installed after the home was finished and we simply converted the existing panel in the garage to be the critical loads panel. As part of the solar + PW install the electrician installed two new panels, a generation panel and a non-critical loads panel, then moved the high wattage circuits to the non-critical loads panel. All told it's a few hours of labor and a new breaker panel (the generation panel may or may not be required for your solar). Unless you have some super fancy panel you have to designate the entire panel to be backed up or not - no splitting as far as I'm aware.

I have 2 powerwalls and backed up everything but my tesla wall connector... so I have an "essential loads" panel with every load for my home except for the tesla wall connector in it. I guess it depends on how complex your specific setup is. The essential loads panel goes close to the main panel (in my case, its on the interior of my garage, on the same wall as my main panel, which is on the outside of my garage on the same wall).

These are construction projects, so you need to look at your individual circumstances... but with that being said, when I got my 3 quotes, all three basically planned on setting up an essential loads panel, even though my stated goal was "whole home backup". They just all suggested I leave the tesla wall connector separate (in main panel) and move everything to the backup loads panel.

This boils down to personal preference and how protected from power outages you want to be, and how much you want to "live like normal" vs "go into camping mode".

I wanted the ability to live like normal, even though I would probably curtail usage of some stuff. My wall oven (40amp circuit) is backed up (for example) but in a real outage situation, I would just bake with one of my BBQ grills (I have different types of BBQ grills, natural gas hooked up to the home, komodo style, and pellet style). I wanted to be able to run my AC "a bit" if in an outage situation, but wouldnt run it much.

Basically, experience has taught me, especially with technology based things, one usually doesnt regret buying the higher end / better thing... they regret not spending the money up front because some feature or other is missing.

People usually dont say "wow my TV is too large! I wish I got the smaller one!". If you get two powerwalls, and backup almost everything, nothing says you HAVE to run everything. the difference is your choice, vs one forced on you by grid being down. That is, of course if one is just making a decision based on "how much do I want / need this" and not "this is cost prohibitive, I cant do it".

This is a really good take, though l'm on the camping side. For us I don't regret only getting one Powerwall at all even though some of the niceties are not backed up. Having lights, fridge/freezer, entertainment, and peace of mind was well worth it and I couldn't justify the expense of a 2nd Powerwall that would sit 99.9% of the year unused in backup only mode. Of course if we had ToU pricing or frequent outages that would absolutely change the math.

 

[SoundDaTrumpet]

@mbroowil You seem concerned on whether or not single vs. double is a better design. What's in your service panel (the one with the meter or the closest one)? Simplicity for my home was to backup the panel filled with all the "110V" circuits (kitchen, rooms, etc.), which turns out to be more complicated because the oven 30A and dryer 30A (unused, but somewhat required) in the panel. For Tesla to relocate those two circuits would have been messy. Good reason for two PWs.

Tesla nailed down the explanation about A/C here. Tesla at their finest:
What does Powerwall Backup | Tesla

Software issues and Nest thermostats. The sizing is usually for to get the compressor going Locked Rotor Amperage (LRA). Usually this doesn't happen simultaneous unless I schedule my A/C to turn on at the same time (Ecobee user here), which I do! Again, my A/C units are offset by PW but not backed up.

My 10 SEER units is going on 16 years, so when they are replaced by state mandated 14 SEER, the efficiency alone will be like getting another PW for free! (Used 40kWh for A/C alone).

 

[charlesj]

I just had 2 power walls installed on May 21. Had a solar system for 8 years and it was a headache when we had power outages infrequent as they were. No solar energy without this PW package. Generator was a hasal too, noise, no 240V outlet in house so only 120V and certainly just 1/2 of the one subpanel.
Yes, I also had a 200A main breaker with 2- 100A subpanels. Seems to use about what you used in one month. My system is only a 3990W system but had no second thought about getting 2 batteries regardless what the suggestions are.

One estimate was by a certified Tesla installer, $10k more that Tesla's 2nd quote and that installer's installation would not have been as clean as in these pictures.
Installation will depend on where main panel is, if you have all breakers in it or you have subpanel/s or not.

Yes, there are 2 power wall there.

 

[wjgjr]

@mbroowil You seem concerned on whether or not single vs. double is a better design. What's in your service panel (the one with the meter or the closest one)? Simplicity for my home was to backup the panel filled with all the "110V" circuits (kitchen, rooms, etc.), which turns out to be more complicated because the oven 30A and dryer 30A (unused, but somewhat required) in the panel. For Tesla to relocate those two circuits would have been messy. Good reason for two PWs.

That is part of why I ended up going with 2 - it made things simple/cleaner since, along with the sure start device Tesla installed, it meant I could do the whole-home backup. Also, at least in my case, the way Tesla was pricing it, there was no increase in the installation/equipment costs (they actually fell a bit,) and they gave another ~$1k discount on the solar+powerwall package. Along with the fed+state (MD) incentives for the 2nd powerwall, it came in at just over $2k net for the second, which helped me make up my mind - knowing it would cost several times that if I wanted to add one later instead.

 

[jjrandorin]

Sorry for the off topic post here but...

Can I say just how much I love this section of TMC? This thread is a perfect example. People really try to help each other here, and new posters with questions are normally treated with respect, and a ton of information as everyone pulls together to try to help them understand their particular needs.

So many smart and helpful people here, its very inspiring! It really does remind me of a "simpler time" when most internet sites were something like this, instead of what we have now (which is decidedly different in most places).

ok, enough with the kumbayaa moment, lol..... i am just so appreciative of how people share info here, and really genuinely want to help others.

 

[mbroowil]

Sorry for the off topic post here but...

Can I say just how much I love this section of TMC? This thread is a perfect example. People really try to help each other here, and new posters with questions are normally treated with respect, and a ton of information as everyone pulls together to try to help them understand their particular needs.

So many smart and helpful people here, its very inspiring! It really does remind me of a "simpler time" when most internet sites were something like this, instead of what we have now (which is decidedly different in most places).

ok, enough with the kumbayaa moment, lol..... i am just so appreciative of how people share info here, and really genuinely want to help others.

As the recipient of all of the information and respect I really would like the second this. Thanks to everyone here!

(I can't believe I haven't received a "search the forum" or "search the web" or RTFM response to a few of my less researched questions... I find the subtleties of this very nuanced... different units for electrical demand, hourly, annual, peak, operating, power, current... will the solar panels operate off-grid... gateways, inverters, micro-inverters...)

Thanks again! (I'm not saying I'm done with questions, I just wanted to thank everyone again)

 

[charlesj]

Certainly. I still and will continue to ask questions myself. Hard to remember all the answers as the use of specific answer may be rarely needed and memory fades.
Luckily we have a good bunch of members who do remember better and are kind and willing to repeat.

 

[jrweiss98020]

I have whole-house backup with 2 PWs. I would recommend that approach, because it is the most flexible. If you lose power when it's sunny, you can still run everything normally during the day, and cut back on high-load items after sunset. If it's the dead of winter, you can choose to shut down whatever loads you consider unessential, and keep the power for the refrigerator and furnace blower.