Experience with Solar and Tesla Powerwall

Jeff

Our experience with solar + home battery during the recent power outage
We have a 3.5 kW solar array and had a 13.5 kWh Tesla powerwall2 battery installed in April.

The battery system was a bit more expensive than a whole-house backup generator and transfer switch, but I liked the idea of being able to power the house indefinitely using the energy gathered from the solar panels during an extended power outage.

Gas stations and natural gas lines might be shut off in certain circumstances, but PG&E can’t shut off the sun! Overall things worked well and we were able to run the fridge, lights, cell phone booster, washing machine, etc. for the entire 75 hours our power was out. But there were a few things I didn’t anticipate that I thought I would share with anyone else considering installing a similar battery backup:

1. The internet also went out which made monitoring the battery charge level and power flow between the solar, battery, and house using the smart phone app fail. There is an alternate way to directly connect to the powerwall system locally through wifi, but it is technically challenging and almost impossible to set up without access to instructions on the internet. I’m very glad I set up the alternate method ahead of time.
2.  When I originally estimated how much power the solar array would produce, I used the numbers from when the powerwall was installed in April. The panels were making about 20 kWh per day then. The real outage happened at a different time of year when the panels were only producing about 12 kWh per day and there were more hours of darkness when the panels weren’t generating power. This meant that we didn’t have enough energy to run our electric clothes dryer and had to restrict running the dishwasher to times the solar panels were making more power than the house was using.

To clarify you have ONE power wall?? Tesla estimated we need 2 but we only have 2000 sq ft, no pool, and really don’t use a ton of electricity

Yes- we only have a single 13.5 kWh powerwall. At the time, two powerwalls seemed like a bit much given the modest size of our solar array. But now that these sorts of extended outages might become a more regular occurrence, I can see the advantage of getting a second powerwall and adding some more solar panels. Things worked out pretty well for us this time, but I still had to keep close tabs on things and hang all our laundry on the tree in the back yard to dry. I'm pretty sure if I completely depleted the powerwall, it would have been really tricky to get the solar inverter to come back online until the grid came back up.

AC:   Jeff  I'm confused about this -- could you please explain? All I know about inverters its that they convert DC current to AC and don't require another power input to work ?

Jeff: It's a special safety feature for solar panels that are connected to the electric grid. Here is a good explanation I found on google:

"In the event of a blackout, a typical grid-tied system has a special automatic shut-off, to prevent that extra energy from being sent over power lines that may be damaged. It's a safety feature intended to protect the line workers who go out to fix things when they break."

The part about variations in solar panel output at different times of the year (and/or different weather conditions) is really important.

The info about monitor/controller challenges when the Internet is down is invaluable.

Just curious: if you are not at home when the PG&E power is shut off OR when power is restored, does the system transition seamlessly and automatically to/from your solar+battery supply? Or do you have to engage with the controls in some fashion?

Also, are you supplying *any* 240V appliances with your system, or (I assume) just 120V stuff?

The power transfer between the grid, solar, and the battery is automatic and almost seamless. The lights flickered briefly when our power went off Saturday night and the wifi rebooted so a UPS is still a good idea for anything sensitive. You are supposed to get alerts on your phone through the Tesla app when the power goes out or comes back on. But this only works if the internet stays on.

We have an air conditioner, electric oven, electric dryer, and electric car charger on separate 240V circuits. The air conditioner isn't connected to the powerwall because our single powerwall doesn't put out enough power to comfortably handle the load from the AC. We avoided using the electric dryer and electric oven (we also have a gas range/oven combo) during the outage. I did use the electric car charger a bit when we had extra solar power after the powerwall was recharged. But I dialed the amperage back to avoid overloading the powerwall. During the summer I would have been able to run the electric dryer while the panels were producing full power.

I heard on KQED that Tesla's giving $1k off on power wall batteries to anyone affected by the power-downs.

I talked with Tesla and it applies only when it is part of installation of solar at the same time. I already have solar installed-from Solar City-which Tesla took over. The $1000 was not applicable to buying a Powerwall to hook u to the solar.

Thank you for this post/ we are just about to sign our contract and still had some question around the power outage and how 1 battery would handle it: this was really insightful.

My husband and I really want to do this same set up! It’s a lot of money but we think it will be worth it. Did it make any difference in your insurance? We were also wondering about re-sale on the house itself after installing something like this. I would think it would help

I haven't mentioned the powerwall installation to our insurance company, but I've heard that some insurance companies will give you a modest discount if you install a backup generator so it might count as a backup generator. The equipment is UL certified so there shouldn't be any negative insurance consequences. This technology is so new that I have no idea about resale value changes for the house. Although I do expect this kind of equipment will get cheaper over time so it probably won't be the same bang-for-the buck as a kitchen or bathroom remodel.

If you don't mind sharing? What is the rough cost of a system like this. I would be interested if I could see a break even point that made sense. We managed okay with the power outage with flashlights and candles. We played a lot of candle lit board games with our teens... we made the most out of it and got to spend some real time with the teenagers! Oh and this would be a great selling feature on a home and increase the demand and resale of a home (I am a local realtor). Thank you so much for sharing your experience. I think you will inspire many to consider similar improvements.

I put our invoice for the powerwall installation in my reply to Ron  below. While the solar was a complete financial no-brainer when we installed it in 2015, the powerwall is a little harder to justify from a strictly financial angle. A natural gas backup generator and transfer switch would be cheaper and would probably perform better in a PG&E outage- as long as the natural gas supply doesn't get shut off. I like the complete self-sufficiency of solar + battery and I'm really interested in this type of technology. And you are absolutely correct that I shared my experiences in the hopes that others would consider doing something similar- or at least be aware of how well this can work and take the plunge once the prices come down to a level they are comfortable with.

When you switch to electric vehicles it makes even more sense to go solar+powerwalls. At that point you will have switched from financially feeding regressive / destructive fossil fuel industries to progressive renewable industries. A huge positive shift for yourself and the planet. I’m completely happy with my Tesla model 3 + Tesla solar and 2 powerwalls. Completely had power through entire outage period, and kept AC circulating through high quality air filter to keep indoor air nice and clean too

If you don't mind sharing could you tell me who your got your panels and batteries from and the sq' of your home.

The solar panels (3.5 kW) were installed in 2015 by solar city (before Tesla bought them). The powerwall was installed by Tesla in April 2019. We have a 2,200 square foot house.

Since I've gotten some PMs about the price, here is our invoice for the powerwall system: Powerwall Energy Storage System, Installation Services, and Purchase Price

• 1 x Powerwall $5,900
• Backup gateway $700
• Installation service $2,750
• Multi-Powerwall installation $0
• Main panel upgrade $0
• Trenching $0
• Hidden conduit $0
• Concrete pad $0
• Additional charges $0
• Permitting fees $150.00
• Taxes $594.00
• Sub-total $10,094.00
• Credit for order payment -$500
• Purchase Price $9,594.00
  
  Thanks so much, Jeff. This is invaluable! We get our solar panels and powerwalls installed next month. We are getting Tesla’s medium solar system and two powerwalls. Our AC units can’t be connected, but the batteries should be able to power our house, major appliances, pool pump and EV. Great tips about the lower solar production this time of year and challenges connecting through the app. Can you please share more about the alternative way to connect directly to the powerwall system locally through Wi-Fi? Also, how did you dial back the amperage to avoid overloading the battery when charging your EV? Thanks again!
  
  For others considering this option, please note that the permitting process took a lot longer than expected and install dates are farther out than Tesla originally estimated. We ordered our system/signed contracts on September 24 and our install date is Dec 17, so about a 3 month wait. Original estimate from Tesla was install by end of October. We’re told that after install it can then take another 2-4 weeks for the inspection to be completed and PG&E to give permission to turn the system on.
  
  Right. Tesla is handling everything for me...permitting, installation, pg&e paperwork, getting their permission to turn the system on.
  
  Were they fast? I’m getting a lot of mixed information about going directly through Tesla .
  
  Tesla was very fast. Installed solar panels, inverter, powerwalls in 4hrs. All has worked very well. Pge was very slow to formally approve the system and enable the solar power credit for feeding excess solar power back to the grid.
  
  so far I have been very happy with Tesla. They’ve been extremely patient with me as I ask all my questions and decide which options to choose. In terms of fast, it’s all relative and the permitting process is out of your control. I would prefer to have an earlier install date, but as long as I get in by the end of year for the tax credit, I’m good.
  
  Here’s my timeline:
  • Beginning of August-started discussions with Tesla team at The Village.
  • August 20 - placed online request for both solar panels and powerwalls. Note-you have to place the requests separately and put down deposits of around $100 for each.
  • August 22 - Tesla technician reached out requesting info about power usage, pictures of panels, etc.
  • August 24 - I submitted all info
  • W/o August 26 - several phone conversations with technician to get all my questions answered. Again, he was very patient with me. We had some complexities because of our existing pool solar system.
  • September 13 - received system info (layouts, output, limitations, process, etc.)
  • Sep 18- another long phone conversation about proposed system
  • Sep 20 - signed contract to move forward
  • Sep 24 - additional info was provided via email and an activation specialist was assigned. She checked in every 10-14 days while we went through the permitting process. I think there is a backlog, as everyone is looking for PG&E alternatives right now and looking to take advantage of the tax credit.
  • Oct 22 - permits came through, scheduler called to explain what would happen day of and get me on the calendar.
  • Dec 17 - first available date for installation.

  do you mind letting me know what the cost was? Did you hav an idea of cost when you visited Tesla in Corte Madera?
  I’m trying to figure out if going through Tesla is cheaper than going through a certified Tesla installer: right now the PW with all plans and permits is about 14k with an install in February. This would push me over to 2020 which my tax credit drops to 26%...but it’s better than nothing .
  
  our pricing aligns with Jeff’s. Yes, the Tesla team at The Village gave us pricing and helped us explore options at a high level. For two powerwalls it was around $18k all in. For the panels, we decided to rent at $130/month for now. In a few years, we want to integrate our pool and house solar systems into one combined system. That might mean a full replacement, so did not make sense to buy the panels at this point.
  
  sounds like going directly through tesla is cheaper. thanks so much for the information. much appreciated.
  
  Adding to the others, thanking you for your account. So helpful. Question about internet. Once your house was powered on via the Powerwall/Solar and your modem had power. Did you have internet then? If so who is your provider.
  
  We have Comcast and I'm not very happy with them right now. The internet stayed on for a few hours after the power went out in our neighborhood, but their backup power must have failed shortly afterwards because we lost internet despite being able to power the modem in our house. I tested things every couple of hours during the outage, but didn't have any luck until the power in our neighborhood came back on. I'm toying with the idea of getting satellite internet since that won't be affected by PG&E outages as long as we have backup power in our house.
  
  I am also starting to think about satellite internet and other alternatives. Comcast is so unreliable. How did cellular hold up during the outage? I was away for most of the outage. Could a Verizon MiFi jet pack provide a similar alternative to internet during a power outage?
  
  D. For cell service I have AT&T and my wife has Verizon. AT&T data and texting went out completely for me about 12 hours after the initial outage. Voice still worked, but that was it. My wife at least had intermittent data, but it was excruciatingly slow when it did work. We used her phone as a hotspot, but it still took minutes to open relatively simple web pages. In Marin, more than half of the cell phone towers went out. Presumably the ones that were still up were overwhelmed with data traffic because comcast internet and the other half of the cell towers were down.
  
  I had no problem with Verizon’s cell service or data – same speeds etc. Just my iphone’s draining battery kept me from using it constantly.
  
  We are looking for a solution. Where did you purchase the backup system? I have called several companies with no response yet.
  
  The Powerwalls are the backup batteries. Purchased through Tesla online.
  https://www.tesla.com/powerwall
  
  you can also use Luminalt solar in San Francisco. They are a certified installer and will order the powerwalls for you. Luminalt.com or 415-641-4000. we had a great experience with them.
  
  A small backup generator did the job for us. The type used by RV enthusiasts will provide 3000 watts plus and ours runs on propane or gas. They are relatively quiet too. Propane is much easier to manage. A small (20 lb) propane tank lasted for 3 days of operation for about 12 hours/day. Plenty of power to run the refrig, heater blower, dishwasher etc, though not all at the same time. No dryer. You can consult an electrician about hooking it up to your panel or just use 12 gage extension cords. Cost with duel fuel and electric start, about $1,100. Costco sells big generators. They provide 8000+ watts, run on gas/propane, have electric start, are very heavy (around 300lb I think) and are pretty noisy. Around $700. Thats a lot of power for the money.
  
  Can you please tell me the brand you purchased, This sounds exactly like what we can afford. We only want to power the frig & freezer, and nothing real heavy. Were seniors
  
  Looks like this evening san rafael wants to amend its noise ordinance during blackouts so people can run generators.
  
  Yes. Heard about this. I also found out is is nearly impossible right now to permit a backup generator in SR due to the noise restrictions. That's insane. My next door neighbor has one (I believe via medical exception) and it popped on when the power went out and I barely heard it. I'd take a little noise and backup power any day over the dark. Hoping SR officials see the logic in amending this based on the PG&E reality.
  
  Jeff what company did you use for the addition of the Powerwall. We have our solar through Solar City which is now Tesla, but I have also seen ads from third party companies. My wife and I are considering and would appreciate the referral. Thanks!
  
  We went directly with Tesla for the powerwall purchase and installation. We put down a deposit a while ago so things may be different if you start the process now. Third party companies also carry the powerwall and they might still have slots for the SGIP incentives. Sunrun also has a similar product called "brightbox" (which I believe is a rebranded LG resu battery with 9.8 kWh capacity) so there are options both for who installs the battery system and which system you go with.
  
  Jeff, thank you for all this information and your experience. When your solar system is running, I assume it feeds back to the grid, and supplies you with income or an offset of your energy costs, is this true? And, if you needed to run it separate from the grid, could you? That is, like an extended power outage?
  
  Before we got our home battery, our solar energy system automatically sent any extra power back to the grid and we got a credit on our electric bill. But the solar energy system is designed to automatically shut down during a power outage so as not to endanger any PG&E employees trying to fix whatever caused the outage. When we got our Tesla powerwall home battery, it came with equipment that would automatically shut off the connection to the electric grid during a power outage and allow the solar energy system to continue producing power to run our house and/or charge the battery so we could power the house after the sun went down. This will allow us to power the house indefinitely during an extended power outage as long as the sun shines at least a few hours a day and we don't completely drain the battery.
  
  I also must add, not everyone has the right situation with sunshine, but we had a lot of generators on, in hazardous high fire potential areas, and they were noisy, and had a lot of exhaust. The fear of fires from the generators made me insane for five nights, as they were on even at night in many cases. This is in Buckingham, in Lake County, where we were during the blackouts. We enjoyed flashlights, candles, sleeping with sundown, meeting more neighbors and eating fresh fruits and veggies that did not need refrigeration. The quietude was nice, but the fear of fires was horrible!!! Solar energy and backup, when possible, seems like such a great option.
  
  We have solar and two batteries from tesla. We have special need child. Let me tell you having power during power outage was blessing. It is expensive but consider 30% tax break and money from PG and e back, it makes a big difference
  
  Do you get the 30% tax break for installing the power wall alone (we’re already leasing solar panels)?
  
  Diana  as long as you connect the powerwalls to solar panels, the tax credit should apply.
  
  That reminds me that there is one aspect of the powerwall I found surprising that I forgot to mention. If you are installing it with solar then it is programmed to only allow the battery to be charged from solar and only discharge in order to power your house. Even though it is technically possible to charge the battery from the grid or sell power from the battery to the grid, the software won't let you do this. This is done to make it eligible for the tax credit.
  
  Not sure if you know this but with the app in storm watch once a storm watch is activated by the weather service the powerwalls will automatically fully charge from the grid. This is incase you do lode power with the storm or PGE shut down
  
  Several years ago we were told that the placement of our house would make solar impractical/useless.
  Aside from getting an assessment with newer materials available, is it practical and/or possible to use the battery walls without solar?
  
  Yes- the powerwall can be configured to work without solar and charge from the grid. But then it isn't eligible for the tax credit. And you couldn't recharge the battery during an extended outage without a whole-house backup generator.
  
  We also have a solar array with a back up battery, an LG. We are in essence our own grid. We designated our fridge and kitchen outlets to be on the battery. So the first night I did not have to empty our fridge or freezer. I could read and even have Netflix, in the kitchen or office. The next night the internet was weakening but that was an inconvenience to the habit, not a true problem. Folks came to charge their phones and have a mtg as the Meeting place went dark. I am proud and privileged that we have this set-up, as not everyone can afford around $17,000, or have their own building, or have sun. But for those in Marin whohave these options, you need to use them, now. This will only continue, and worsen. Unless, of course, climate change is a hoax. I presented our system at a Drive Clean/go electric event the very day we Gad the first shutdown. If you want more information, I am available.
  
  Does anyone have experience with a Generac generator that uses natural gas? Thanks,
  
  I just met with my electrician today to ask about these, they say they’ve been installing a lot of them lately. They were a great source of info on helping me choose right sized generator for my house and configuration for where it would go. I can give you the name or put you in touch if you’re interested.
  
  I have a Guardian generator that used natural gas and powered my entire house (automatically goes on and off). A neighbor helped me with the cellular problems. I am 84. Can’t imagine dealing with the battery option. My husband at one point was dependent on electric devices— oxygen, a hospital bed, tummy tube, etc. My system is expensive but worth every penny. Installed 12 years ago. No problems.
  
  What if... in an earthquake, the gas is turned off?
  
  Great insight, Jeff. When you bought it, did you look at other types of batteries. It looks like a nice neat system. I also would like to know who installed it.

  I read somewhere that off-brand house batteries have a risk of explosion. Like with laptop batteries. Toxic smoke, etc., firefighters are grappling with this now...