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Powerwall Line Conditioning?

commasign

TeslaAdviceBlog.com
Aug 31, 2013
3,202
4,178
Davis, CA
Anyone know if Powerwall performs any line conditioning? When I have my Powerwalls set to backup only, my Model S and X occasionally have “charge interrupted” messages on the mobile app or “no power - check wall connector” error on the dash screen (blue port). But when Powerwalls are in self-powered mode, I get no charging errors at all from my cars. I charge the cars during Powerwall charging and discharging states.
 

GenSao

Member
Aug 3, 2017
550
938
Pleasant Hill, CA
IMHO, to a minor degree, Yes.

But it is not a proper substitute for a line conditioning device and the Powerwall is not advertised as one. There is no direct protection of equipment, no guarantee to remove noise from the AC line, no formal corrections to voltage fluctuations and waveform distortions, and any guaranteed system protection.

Powerwalls can condition the power line and act like an an Active Power Filter (APF) since they are are more sensitive to fluctuations in the power line in self-powered mode. The gateway monitors fluctuations in power and adjusting the Powerwall(s) on an ongoing basis. In backup only mode the Powerwalls are only need to respond when power cuts off. So monitoring may be a bit more relaxed as you have notced.

Per Wikipedia,
"Active power filters (APF) are filters which can perform the job of harmonic elimination. Active power filters can be used to filter out harmonics in the power system which are significantly below the switching frequency of the filter. The active power filters are used to filter out both higher and lower order harmonics in the power system."

Powerwalls does not filter the power line completely like other commercial solutions. Powerwalls seem to injecting active power with the same/similar frequency as the grid but it is unclear if they provide the reverse phase to cancel harmonic distortions required to remove noise from the power line. Prehaps the power from the Powerwall is cleaner and helps averaging down (not out) any distortions of the grid. On the flip side, it could be similar or worse than the grid.

Powerwalls can adjust the line voltage as needed to "universally" turn off solar panel inverters in an off-grid state,. It is unlikely (or unclear) that the Powerwall is actively condition the voltage to a nominal value.
 

miimura

Well-Known Member
Aug 21, 2013
6,375
6,081
Los Altos, CA
Powerwalls can adjust the line voltage as needed to "universally" turn off solar panel inverters in an off-grid state,. It is unlikely (or unclear) that the Powerwall is actively condition the voltage to a nominal value.
Correction: Powerwall curtails solar by changing the frequency, not voltage when the batteries are full in a backup power situation.
 

boaterva

Supporting Member
Apr 2, 2016
7,570
3,743
Northern Virginia, USA
I was thinking along these lines... what would one need to do, then, if one wanted to use or have a whole house UPS? The PWs act as a sort of one, since they serve as power backup, but they don’t do conditioning that a UPS may do or (I assume) do spike/surge control.

What else would need to be added to a Solar/PW system to have the equivalent of a ‘protected by a complete UPS/surge system’? A whole house surge suppressor? I’ve never heard a definitive answer on the worth of those, so comments appreciated!
 

GenSao

Member
Aug 3, 2017
550
938
Pleasant Hill, CA
If you have enough electronics that are sensitive to power fluctuations, then it may be a good idea to install a whole house surge suppressor. The cost is not too much more, especially if you are doing electrical work with a Powerwall and/or solar install. This would be similar to a good quality surge protector strip.

It should be considered an added level of protection and not replace the use of regular surge protector or UPS in the home. At a minimum it should be installed in the first panel that is connected to the grid. Optionally, surge suppressors can be installed in every other major panel (excluding the gateway).

A complete UPS is much more expensive and may not be worth the cost. Of course if you have a secret laboratory that uses a lot of sensitive equipment, then it is a must! =)
 
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Reactions: boaterva

Skipdd

Supporting Member
Dec 30, 2015
681
572
Silver Spring, MD
If you have enough electronics that are sensitive to power fluctuations, then it may be a good idea to install a whole house surge suppressor. The cost is not too much more, especially if you are doing electrical work with a Powerwall and/or solar install. This would be similar to a good quality surge protector strip.

It should be considered an added level of protection and not replace the use of regular surge protector or UPS in the home. At a minimum it should be installed in the first panel that is connected to the grid. Optionally, surge suppressors can be installed in every other major panel (excluding the gateway).

A complete UPS is much more expensive and may not be worth the cost. Of course if you have a secret laboratory that uses a lot of sensitive equipment, then it is a must! =)


I evaluated whole house UPS 7 or so years ago and the cost was huge. This was before Powerwall existed. Our local electric co was having multiple outsges per year, and I was tired of going w/o power for key things. Whole house generator cost also crazy expensive, so we opted for Honda EU series generator that provided clean power via inverter. Then WAPO exposed the utility by publishing a graph showing the inverse relationship between reduced maintenance spend and increased outages. And the local PUCs excoriated and fined the utility. Things started to get better.. We already had a whole house surge protector.. another sad electric utility story

Years before, after our HVAC electricals blew out twice in a row. After the Electric company brought out a UUGE meter and then claimed all was well. And then the HVAC boards on a brand new inside unit blew again, we paid an electrician to put in a surge protector in between the main power feed and main panel. No more problems. Surprise.

Fast Forward to 5 years ago. Electric utility replaces underground power cables. As they open up a trench in my yard, guess what is found? A SPLICED power cable with red tape wrapped around the outside...
 

boaterva

Supporting Member
Apr 2, 2016
7,570
3,743
Northern Virginia, USA
Thanks for the useful comments (how did anyone get anything done before the Internet (and I remember those days...). Maybe when I get the PWs installed (this fall, lol?) I'll see if they can add in a whole house surge suppressor... that's when they will be ripping everything apart, for sure!

TE solar panel contract is in, so that's the first step (no constraints on panels like PWs!)).
 

mongo

Well-Known Member
May 3, 2017
13,133
40,041
Michigan
PW can't condition since the grid is more powerful than it is. They 'could' be set up as a large UPS/ conditioner through some smart switch and control.

Basically, one PW is connected to sensitive loads and one PW is charging off grid. Th grid was gets turned off, switched to the load side, then turned back on (so that it synchronizes with the other). Then the original load one gets turned off, switched to the grid, and turned back on to charge.

Old school power conditioning/ UPS is a 3 Phase motor spinning a flywheel and 3 phase generator (with one way clutch if desired).
 

miimura

Well-Known Member
Aug 21, 2013
6,375
6,081
Los Altos, CA
A Double Conversion UPS is basically a grid connected battery charger and an independent inverter sized to supply the full load of the connected circuits. If the Powerwall design was changed to provide a separate "Generator Input" that just had a battery charger on it, then the Powerwall could be wired and used as a Double Conversion UPS.
 

mongo

Well-Known Member
May 3, 2017
13,133
40,041
Michigan
A Double Conversion UPS is basically a grid connected battery charger and an independent inverter sized to supply the full load of the connected circuits. If the Powerwall design was changed to provide a separate "Generator Input" that just had a battery charger on it, then the Powerwall could be wired and used as a Double Conversion UPS.

Yah, or if they took 2 PWs and connected the packs together, one would charge and the other would be the inverter.
 

miimura

Well-Known Member
Aug 21, 2013
6,375
6,081
Los Altos, CA
Yah, or if they took 2 PWs and connected the packs together, one would charge and the other would be the inverter.
Then you're cutting the inverter to capacity ratio in half. It's better to add the 5kW battery charger to each Powerwall so you can scale the power output 1:1 with each additional Powerwall.
 

mongo

Well-Known Member
May 3, 2017
13,133
40,041
Michigan
Then you're cutting the inverter to capacity ratio in half. It's better to add the 5kW battery charger to each Powerwall so you can scale the power output 1:1 with each additional Powerwall.

Well sure, two 5kW charger and two 5kW inverters put out more than one of each (if you have a pack that can handle 10kW during UPS operation). I was just saying what Tesla could do without any significant change to the current product.
 

miimura

Well-Known Member
Aug 21, 2013
6,375
6,081
Los Altos, CA
Well sure, two 5kW charger and two 5kW inverters put out more than one of each (if you have a pack that can handle 10kW during UPS operation). I was just saying what Tesla could do without any significant change to the current product.
Providing an external direct battery connection would be a significant change to the current product. If it was available that way, it would be a very good way to connect a 3rd party battery charger for generator backup. ;)
 

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