Powerwall for Planned Power Outages

[SoundDaTrumpet]

I live in California in an area that PG&E can sometimes decide to turn off the power.
I live on the peninsula on the west side of the San Francisco Bay. We are not very windy and don't have those dreadful winds that other areas of California get. But PG&E can decide what they will. Where I immediately live they did not turn the power off in 2019.

In other words, you are not affected by the PSPS. This alone reduces the benefit of getting a Powerwall as it did for me.

But now with the coronavirus, the former backup plan was to just pack up a few things and find a hotel with the power on. Seems like a less viable solution now. And food in the refrigerator and freezer seems more valuable than in 2020. The former argument was say even a $300 a night hotel for say 3 nights would be only $1000 a year if it is required.

What you pointed out here is why I "liked" your post.

So looking for a powerwall or another brand equivalent. Elon's recent behavior makes me much more open to a non-Tesla alternative. I have briefly looked at a generator option but these do not seem any cheaper and the greenie in me rebels against the thought.

Elon has the desire for competitors to succeed. I investigated a natural gas - based generator since natural gas is cheap given but Powerwall ended up being cheaper with incentives/credits I have already received.

I have a 13 year old solar system that I think is producing 3.8kW - but I for the life of me can't find the documentation. It is a little less than I could use as I pay up a couple hundred dollars a year to PG&E, but it is likely too old to expand.

Your system minus PWs matches mine. 2 PW setup n fire season is perfect, in cooler weather PV is at peak efficiency, and A/C usage is zero.

What I have not been able to find anywhere is succinct information on why I can't keep charging the powerwall during an outage if the solar is active.

Generally speaking the majority of PV owners have larger PV system, if the solar system generates more than X.X kW, a single PW can't handle it. It is likely the specification for PW might be lower for recharging. It can certain discharge at 5K, but recharge might be lower.

If this capability were there, I think 1 powerwall would be enough. But the Tesla person said that feature is not available. Technically why not?

Installing 1 PW involves a lot of working pulling individual circuits and installing a critical/backup load center for just your few circuits. It's easier to backup an entire subpanel with say a 125A branch circuit, than the numerous 15/20/30A branch circuits. This critical loads center needs to located really close to the subpanel feeding the house (assuming the house circuit breakers aren't located at the meter).

I'm perfectly okay with just running the fridge, the internet, and a few small devices such as laptop, microwave, phones etc... during an outage. If this low usage model will work with 13.5kWh, 1 powerwall should be sufficient. No need to run things like dishwasher, laundry, A/C (its not that hot here) or charge the car (go to a supercharger). Am I missing something?

Read what I wrote above. It's easier to rope in the "lighting" and "outlets" from the bedrooms and include them. Approach this at the subpanel level, and not at a per plug basis.

 

[cali8484]

I live in California in an area that PG&E can sometimes decide to turn off the power.
I live on the peninsula on the west side of the San Francisco Bay. We are not very windy and don't have those dreadful winds that other areas of California get. But PG&E can decide what they will. Where I immediately live they did not turn the power off in 2019.

But now with the coronavirus, the former backup plan was to just pack up a few things and find a hotel with the power on. Seems like a less viable solution now. And food in the refrigerator and freezer seems more valuable than in 2020. The former argument was say even a $300 a night hotel for say 3 nights would be only $1000 a year if it is required.

So looking for a powerwall or another brand equivalent. Elon's recent behavior makes me much more open to a non-Tesla alternative. I have briefly looked at a generator option but these do not seem any cheaper and the greenie in me rebels against the thought.

I have a 13 year old solar system that I think is producing 3.8kW - but I for the life of me can't find the documentation. It is a little less than I could use as I pay up a couple hundred dollars a year to PG&E, but it is likely too old to expand.

What I have not been able to find anywhere is succinct information on why I can't keep charging the powerwall during an outage if the solar is active. If this capability were there, I think 1 powerwall would be enough. But the Tesla person said that feature is not available. Technically why not?

I'm perfectly okay with just running the fridge, the internet, and a few small devices such as laptop, microwave, phones etc... during an outage. If this low usage model will work with 13.5kWh, 1 powerwall should be sufficient. No need to run things like dishwasher, laundry, A/C (its not that hot here) or charge the car (go to a supercharger). Am I missing something?

Do you have a Tesla car? Given your goal is just keep the essentials (e.g. fridge, lights, internet, phones, laptops) going during power outage you could use the huge Tesla car battery (much bigger than Powerwall) if you have one. Check MASTER THREAD: Powering house or other things with Model 3 12V battery for more info.

In any case, you should have a generator for backup even if you get a Powerwall. Clouds/smoke kill PV production.

 

[cali8484]

Okay, another potential roadblock. My wi-fi in that part of the garage and house is pretty lame. I have a lot of stone walls and stainless steel and fancy stuff that interfere. Its pretty far away from either the router or the extender that is wired under the house. Anyone have a clue on this part?

Cellular signals are there but weak also due to topography (hills).

Powerwall (or another home battery) installation will likely involve significant electrical wiring changes to your house so it would likely be small incremental work to add Ethernet wiring if needed. The likely main issue is still your PV array is probably too small to keep the Powerwall charged consistently.

 

[jrweiss98020]

"barring any extended rainy days."

If there were extended rainy days, we would not have any power shut offs as the wildfire planned outage would not be in effect!

OTOH, there may be lots of smoke, which will also reduce PV output...

 

[jrweiss98020]

Okay, another potential roadblock. My wi-fi in that part of the garage and house is pretty lame. I have a lot of stone walls and stainless steel and fancy stuff that interfere. Its pretty far away from either the router or the extender that is wired under the house. Anyone have a clue on this part?

A couple possible solutions:

Replace your router with one of the new "mesh" systems. You can use 3 or 4 units that should cover almost any reasonably-sized house.

Replace the extender with a WAP (wireless access point) that has wired Ethernet ports that can be hooked up to the Gateway. You might be able to find a good price on a Linksys WRT1900AC or WRT3200ACM, both of which can be configured as routers, extenders, or WAPs. The WRT series will have MUCH more power output than a cheap extender.

 

[gpez]

I think your rough calculations are very good. I looked at Saturday May 9 and 10kWh/day was sent to the grid. That was the max. So even on a sunny day (well mostly sunny) in almost summer no car charging and regular usage, I agree with you. I won't be able to generate enough electricity for a second Powerwall.

I don't follow this, could you help me understand @Owner?

The size of the battery matters only for periods of time that the PV is not producing. "I won't be able to generate enough electricity for a second Powerwall" is a time-bound statement because if your consistently overproducing you'll eventually run out of capacity even with multiple Powerwalls.

Some numbers would really help! How much does your solar produce on average and maximum and how much power do you use (or would project to use during an outage) both in a 24 hour period and when the sun is not up?

As an example my 8.6kw system produces at max 50kWh on cloudless summer days. Normally with EV charging and normal power use we consume 25-35kWh/day. During an outage we can reduce that to 12kWh/day with minimal life-impacting conservation, could likely get it down to 6kWh/day with the bare minimum (fridge/freezer, lights, tankless hot water heater). The single Powerwall would last about a day in the first scenario, two in the second. All that matters though when the sun is shining enough to compensate for a full day's usage is that the Powerwall not drain fully before the sun rises. One Powerwall is plenty for that even though my system has the capability to produce 4x it's storage capacity.

Does that make sense?

 

[jboy210]

Okay, another potential roadblock. My wi-fi in that part of the garage and house is pretty lame. I have a lot of stone walls and stainless steel and fancy stuff that interfere. Its pretty far away from either the router or the extender that is wired under the house. Anyone have a clue on this part?

Cellular signals are there but weak also due to topography (hills).

Can you run another Ethernet line or consider updating your Wifi network to a mesh network? You just need to plug in a few mesh units into the wall sockets around the house to get pretty solid wifi throughout even a big house.

 

[Owner]

I don't follow this, could you help me understand @Owner?


Some numbers would really help! How much does your solar produce on average and maximum and how much power do you use (or would project to use during an outage) both in a 24 hour period and when the sun is not up?

As an example my 8.6kw system produces at max 50kWh on cloudless summer days. Normally with EV charging and normal power use we consume 25-35kWh/day. During an outage we can reduce that to 12kWh/day with minimal life-impacting conservation, could likely get it down to 6kWh/day with the bare minimum (fridge/freezer, lights, tankless hot water heater). The single Powerwall would last about a day in the first scenario, two in the second. All that matters though when the sun is shining enough to compensate for a full day's usage is that the Powerwall not drain fully before the sun rises. One Powerwall is plenty for that even though my system has the capability to produce 4x it's storage capacity.

Does that make sense?

Yes, but unfortunately that's really hard to give you those numbers. I just don't really have them. PG&E only tells you the final results. I didn't put on a meter in-between. So it is guess work.

But pre-COVID - usage was about 25kWh/day, now down to more like 17kWh/day due to a lot less driving as there is nowhere to go.
pre-COVID averaging 50-50 car/house
now more 25-75 car/house

So that's around 12kWh/day for the house. Minimum lighting requirements here and not a lot of use of entertainment devices. My scenario assumes charging at the superchargers.

The max that gets sent to the grid on a cloudless (all summer days are cloudless here) is 15kWh/day with no one at home.

So if the 1 powerwall was in use, that would last 1 day if it didn't get refreshed. If there is a wildfire thing going on, it typically is before a wildfire with a lot of wind, so the air is typically clean as it has been blown clear.

 

[Owner]

Can you run another Ethernet line or consider updating your Wifi network to a mesh network? You just need to plug in a few mesh units into the wall sockets around the house to get pretty solid wifi throughout even a big house.

I can't run another Ethernet line, or well it is possible but not quite worth the trouble. I tried a cheap extender but it didn't work. I haven't tried a mesh network I should look into that anyways.

 

[Owner]

OTOH, there may be lots of smoke, which will also reduce PV output...

the power outages are for pre-wildfires. When it is windy and likely no smoke yet.

 

[SoundDaTrumpet]

I can't run another Ethernet line, or well it is possible but not quite worth the trouble. I tried a cheap extender but it didn't work. I haven't tried a mesh network I should look into that anyways.

Another Ethernet line? You make it sound like you have ethernet on your solar inverter. I bet your solar inverter has an extra port (open up and see). Then use double jacketed 600V ethernet cable, which I used to run in the existing conduit between gateway and inverter via the backup load center. Else run a separate PVC conduit between the inverter and gateway.

 

[Owner]

Another Ethernet line? You make it sound like you have ethernet on your solar inverter.

No, the house is kind of a triangle. One corner is where the modem is and kind of close by is the main power source. At another point is the garage, I just don't get good wifi there. I put the second ethernet line under the house that goes to the 3rd triangle point back when we used wires. The garage does not have a crawl space. The stainless steel fridge, stainless doors on the opening to the bbq cause a lot of problems with wifi.

I like the idea of trying a mesh network, some look beefy enough to cover a lot more than what I'm getting now.

 

[SMAlset]

They hooked up our powerwalls to our router through a powerline adapter.

Interesting. We might need something like this but not sure yet. Did they supply it or did you have to buy one yourself?

 

[SMAlset]

@Owner, you stated that your PV system is 13 years old already and you weren't sure of it's rating. Just wondering with advancements in solar panels, inverters and gateways, might it pay to look into a new system which might be able to generate more power and that uses some type of a microinverter system if you get any shade or even with shading from cloudy days? We are waiting for our Solar and PW system to be installed, but the solar panels Tesla is using for our house is from Hanwah Q Cells, specifically the Q.Peak Duo Blk-G5 model and paired with a Solar Edge inverter. Q.PEAK DUO BLK-G5 : Residential & Small Commercial : U.S. & CANADA : SOLAR PANELS : PRODUCTS : Q CELLS Both together look to have some very nice features especially for cloudy/partially cloudy days which I assume by the coast there you might have. If you are considering upgrading your current system, think about donating your solar panels and inverter to something like Habitat for Humanity. I've seen on the news where homeless people are recycling older discarded systems to help power their phones. Donating to a group like Habitat you could probably get a tax deduction (not sure if that's even something these days with changes to IRS forms).

With the 26% Federal ITC credit and some of the current pricing on PWs (and possibly the PG&E SGIP incentive--we don't qualify under their new special programs), it might be worth it to think about upgrading now and taking advantage of it particularly if you will be staying in your home and don't have plans for moving.

We are in PG&E's PSPS area and did go through one shut off in 10/2019. But before that I recall we also got affected by some rolling power blackouts when the temps were really hot all over and they were asking people and businesses to conserve. With the weather these days who knows what to expect temperature wise. If you are in a position to WFH now or in the future (some companies will maintain that through the year end from what I've heard), having power to use your computer, etc. is another plus to having the battery back up. And totally hear you about the refrigerator/freezer especially during Covid. One power outage took out our food and that was when it was much easier to buy food before Covid.

 

[nwdiver]

I live in California in an area that PG&E can sometimes decide to turn off the power.
I live on the peninsula on the west side of the San Francisco Bay. We are not very windy and don't have those dreadful winds that other areas of California get. But PG&E can decide what they will. Where I immediately live they did not turn the power off in 2019.

But now with the coronavirus, the former backup plan was to just pack up a few things and find a hotel with the power on. Seems like a less viable solution now. And food in the refrigerator and freezer seems more valuable than in 2020. The former argument was say even a $300 a night hotel for say 3 nights would be only $1000 a year if it is required.

So looking for a powerwall or another brand equivalent. Elon's recent behavior makes me much more open to a non-Tesla alternative. I have briefly looked at a generator option but these do not seem any cheaper and the greenie in me rebels against the thought.

I have a 13 year old solar system that I think is producing 3.8kW - but I for the life of me can't find the documentation. It is a little less than I could use as I pay up a couple hundred dollars a year to PG&E, but it is likely too old to expand.

What I have not been able to find anywhere is succinct information on why I can't keep charging the powerwall during an outage if the solar is active. If this capability were there, I think 1 powerwall would be enough. But the Tesla person said that feature is not available. Technically why not?

I'm perfectly okay with just running the fridge, the internet, and a few small devices such as laptop, microwave, phones etc... during an outage. If this low usage model will work with 13.5kWh, 1 powerwall should be sufficient. No need to run things like dishwasher, laundry, A/C (its not that hot here) or charge the car (go to a supercharger). Am I missing something?

What's your budget looks like? The most cost effective option might be swapping your current 3.8kW inverter for a new 3.8kW SMA with SPS (Secure Power Supply). You can probably do that for <$2k.

 

[CrazyRabbit]

If you have solar you can only charge from the grid under stormwatch. If the weather service expects an event in your area or if there is a planned outage then the battery will prepare itself by charging from the grid. Otherwise it's expected you get all your battery charging from solar. If you play with the advanced time based controls you can get the battery to charge from solar while you run the house off the grid.

to get the tax credit on the powerwalls that is how it works. if you don't want the tax credit then you can charge from the grid...
tesla has a distributed generation agreement with some municipalities where the walls will dump to the grid, if you enable the feature, in rare instances and then charge from the grid.

 

[Owner]

If you are considering upgrading your current system, think about donating your solar panels and inverter to something like Habitat for Humanity. I've seen on the news where homeless people are recycling older discarded systems to help power their phones. Donating to a group like Habitat you could probably get a tax deduction (not sure if that's even something these days with changes to IRS forms).

With the 26% Federal ITC credit and some of the current pricing on PWs (and possibly the PG&E SGIP incentive--we don't qualify under their new special programs), it might be worth it to think about upgrading now and taking advantage of it particularly if you will be staying in your home and don't have plans for moving.

I love this idea! Yes with the credit and incentives it could happen.

But then I hit this snafu.... To be eligible for tax credits, you must have a tax liability at least equal to the credit.

I didn't really get the credit on the cars... Financial people can be clever to help you avoid being taxed.

 

[charlesj]

..

We did an endurance test last year and went 8 days (over 200 hours) off the grid, just using solar and Powerwalls.

May have asked before but could you have continued beyond 8 days or weather just didn't cooperate enough after 8 days?

 

[charlesj]

They hooked up our powerwalls to our router through a powerline adapter.

How is that working out for you? Is it Tesla's powerline? I may need such a setup next Thursday as the Gateway is pretty far for wi-fi and it uses the older G protocol. My wi-fi is on the N protocol for 2.4Gig band as it is faster than the G and auto mode would slow it down to the G speeds.

I relocated my Enphase Enlighten that used their powerline to connect to router but now I don't need it. Perhaps that may work as well as all it is doing, I think, is just transmitting digital data over the 240V house wiring.

 

[Mokuzai]

How is that working out for you? Is it Tesla's powerline? I may need such a setup next Thursday as the Gateway is pretty far for wi-fi and it uses the older G protocol. My wi-fi is on the N protocol for 2.4Gig band as it is faster than the G and auto mode would slow it down to the G speeds.

I relocated my Enphase Enlighten that used their powerline to connect to router but now I don't need it. Perhaps that may work as well as all it is doing, I think, is just transmitting digital data over the 240V house wiring.

Tesla brought it but it is just a retail TP-Link powerline adapter. It was plugged into the same outlet that we had our enphase envoy unit plugged into since it's the closest outlet to the main panel. The envoy uses a wifi dongle to communicate with our router. This caused a problem with the envoy not reporting all the micro-inverters. Was able to fix this by moving the envoy to a different outlet in the room.