Powerwall design with 100 amp meter main feeding two subpanels

[fuzzywuzzy1]

Hi,
I have a 100 amp meter main (with 1 disconnect). Currently the meter-main feeds house subpanel which is rated at 125 amps, my load-calculation is much low, like 60 amps. I am doing an addition which has its own 125 amp subpanel(load calculation on this this is also around 65 amps). I am thinking of adding solar 4.86 kW with Powerwall system to feed both the subpanels. Is that possible? I would like not to touch/upgrade the meter main - as that would require trenching/working with utility == huge cost.
Can the solar and grid both feed the 2 subpanels? If yes, what's the possible wiring diagram?

Solar ----| |---Subpanel 1
+----PW System --
Grind ---| |---Subpanel 2

 

[miimura]

The best way for someone to understand your true situation is to post a picture of your main panel showing all breakers and a legible picture of all the labels inside. There is a lot of detailed information about the panel on those labels.

In any case, it's probably possible to leave the main panel alone and use either the Backup Switch behind the meter or a Powerwall Gateway 2 with built-in breaker panel to handle your situation. To give any more detail, we would need to see the main panel. The Powerwall system has a Power Control System so you can put many backup loads and still not overload the 100A main.

 

[fuzzywuzzy1]

 

[BGbreeder]

Hi,
I have a 100 amp meter main (with 1 disconnect). Currently the meter-main feeds house subpanel which is rated at 125 amps, my load-calculation is much low, like 60 amps. I am doing an addition which has its own 125 amp subpanel(load calculation on this this is also around 65 amps). I am thinking of adding solar 4.86 kW with Powerwall system to feed both the subpanels. Is that possible? I would like not to touch/upgrade the meter main - as that would require trenching/working with utility == huge cost.
Can the solar and grid both feed the 2 subpanels? If yes, what's the possible wiring diagram?

Solar ----| |---Subpanel 1
+----PW System --
Grind ---| |---Subpanel 2

A few things;
Your meter appears to be a 200A meter, with a 200A main breaker (2x100). Usually, there is a sticker with the details of your particular panel somewhere, and those exact details may affect the actual plan.

You might want to check with your and other solar installers about what they propose as necessary; around here replacing a meter and main service panel is neither a huge cost, nor a big deal, though your particular details may affect the costs. We replaced ours to upgrade the panel. The utility sent a linesman out in the morning to cut the service drop to the house and he returned several hours later to splice in the new service drop to the newly installed main service panel. Splicing three utility wires took him less than twenty minutes.

Power is power. Whether you inject the power at point A or point B doesn't matter as long as the wires between them have sufficient capacity (strictly speaking, ampacity). Think of it as water in a water filled hose that pours out whichever end is lower.

I would get a few (more) quotes from solar installers. Just going through the quotes should give you more information.

Finally, I would drill down on your actual usage. You have a smart meter. Go to your utility account(s), and look through your usage by time of day, day, week and month to get an idea of how much power (kWh) you actually use, and what your peak draw (kW) actually is. Then add in any proposed upgrades, like your ADU, and see where you are. Armchair quarterbacking, 60A for Fremont, CA is a pretty sizable load without rapid charging an EV.

All the best,

BG

 

[fuzzywuzzy1]

A few things;
Your meter appears to be a 200A meter, with a 200A main breaker (2x100). Usually, there is a sticker with the details of your particular panel somewhere, and those exact details may affect the actual plan.

>> What does it mean to have 2 x 100 amp breakers? Does a breaker get associated with a subpanel connection? I already have the main subpanel connected to it, Does it mean I can connect another 100 amp subpanels to the meter main as of today?

You might want to check with your and other solar installers about what they propose as necessary; around here replacing a meter and main service panel is neither a huge cost, nor a big deal, though your particular details may affect the costs. We replaced ours to upgrade the panel. The utility sent a linesman out in the morning to cut the service drop to the house and he returned several hours later to splice in the new service drop to the newly installed main service panel. Splicing three utility wires took him less than twenty minutes.

Power is power. Whether you inject the power at point A or point B doesn't matter as long as the wires between them have sufficient capacity (strictly speaking, ampacity). Think of it as water in a water filled hose that pours out whichever end is lower.

I would get a few (more) quotes from solar installers. Just going through the quotes should give you more information.

Finally, I would drill down on your actual usage. You have a smart meter. Go to your utility account(s), and look through your usage by time of day, day, week and month to get an idea of how much power (kWh) you actually use, and what your peak draw (kW) actually is. Then add in any proposed upgrades, like your ADU, and see where you are. Armchair quarterbacking, 60A for Fremont, CA is a pretty sizable load without rapid charging an EV.

>> the 60 amp calculated was the peak usage, my actual usage over time has never gone up above 25 amps.

All the best,

BG

 

[jjrandorin]

I am thinking of adding solar 4.86 kW with Powerwall system to feed both the subpanels. Is that possible?

What did the companies that you contacted to get quotes propose? If you dont have any quotes yet, you should start with getting at least one, to get a professional opinion on what an installer says is possible.

 

[Vines]

Looks to me like a 100A 2-pole main breaker-only service, which should easily support a 4-5 kW system. I do not see a sticker on it, so doubt we can call it a 200A unit.

The pv connection is pretty trivial, and will feed all your loads on your side of the meter. Get a hold of your preferred installer and start the quote process, there should not be many issues with this.

 

[wwhitney]

Your meter appears to be a 200A meter,

Yes. But that doesn't mean the service is 200A, it can be lower.

with a 200A main breaker (2x100).

No, that's a 100A double pole main breaker. So the existing service is 100A.

Cheers, Wayne