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Power Outage with Powerwalls
We have a Tesla Energy PV system and two Powerwall 2's which were commissioned about two months ago. We live in the Phoenix AZ area.
A few days ago, during a thunderstorm, my wife and I were working at our computers in our office when, at 4:30pm, we noticed that the lights flickered off once, and our DSL modem retrained. Our computers were unperturbed. Such a flicker is not all that unusual during thunderstorms, so we went about our internet activities. But about 10 minutes later, I started thinking, "what if there was a power outage, and our home batteries were switched in?" I looked outside, and sure enough, the neighborhood was dark, and we were the only ones with power. I might not have known.
The Tesla application revealed that our battery system was indeed powering the house, and the solar panels were providing no power due to the clouds.
When we realized that we were on backup for a yet undetermined period of time, we increased the thermostats from 80 degrees F to 85 degrees F and turned off unnecessary lights and phantom loads. The main loads resulting in the 0.7kW draw were the refrigerator and a medical device required for recovery from a recent hospital stay. We left a few house lights (LED's) and fans on, but turned off the outside lights to avoid being accused of witchcraft. Our home network, router, and modem were left on. The result was a 0.7kW load.
The backup power source consists to two Tesla Powerwalls 2's in our garage configured via the application to retain a 45% reserve for possible outages throughout all of their activities.
Given the reduced house load, that reserve would last us about 12 hours. After that, we would not open the refrigerator and we would need to use (and possibly order additional, which had me a little worried) mechanical backup for the medical device. The utility company's web page indicated that the outage in our area was projected to last until 8:30am the next day, but they're usually pessimistic. Nevertheless, we had to plan for that.
So, we didn't watch television or listen to the stereo, but we did use the kitchen facilities (blender, seed grinder and lights, while opening and closing the refrigerator numerous times) to make smoothies. And we read and surfed.
I periodically checked the application for status to monitor our reserve capacity, and eventually, round 9:30pm (five hours later), the application indicated that the grid was back up, and the battery reserve was no longer in use.
If we had known that the outage would have been this "short," we may have streamed a movie on our big system or cooked a meal with electric appliances. But, we plan for the worst.
The outage depleted our 45% reserve to 32%. I was concerned that the following day, with extreme AC demand and cloudy weather, there would not be enough excess PV production to recharge the battery to the reserve threshold. However, as soon as the sun came up, all PV production was diverted by the energy gateway to the batteries, and when I got out of bed and checked, the capacity had already been replenished to 45%, and normal operation had resumed. I was impressed with the sophistication of this control algorithm, and overall, my expectations have been exceeded.
One problem that I see is that, whether we were at home or away, we may not have been aware that an outage was in progress and would have gone about running the AC and pool pump and charging the car, thus depleting the battery much more rapidly. We have to keep an eye on that. Since the application runs on a mobile device (not windows, unfortunately ... we had to acquire an android device specifically to run this application), we can monitor the system remotely and get home quickly if we need to.
A few days ago, during a thunderstorm, my wife and I were working at our computers in our office when, at 4:30pm, we noticed that the lights flickered off once, and our DSL modem retrained. Our computers were unperturbed. Such a flicker is not all that unusual during thunderstorms, so we went about our internet activities. But about 10 minutes later, I started thinking, "what if there was a power outage, and our home batteries were switched in?" I looked outside, and sure enough, the neighborhood was dark, and we were the only ones with power. I might not have known.
The Tesla application revealed that our battery system was indeed powering the house, and the solar panels were providing no power due to the clouds.
When we realized that we were on backup for a yet undetermined period of time, we increased the thermostats from 80 degrees F to 85 degrees F and turned off unnecessary lights and phantom loads. The main loads resulting in the 0.7kW draw were the refrigerator and a medical device required for recovery from a recent hospital stay. We left a few house lights (LED's) and fans on, but turned off the outside lights to avoid being accused of witchcraft. Our home network, router, and modem were left on. The result was a 0.7kW load.
The backup power source consists to two Tesla Powerwalls 2's in our garage configured via the application to retain a 45% reserve for possible outages throughout all of their activities.
Given the reduced house load, that reserve would last us about 12 hours. After that, we would not open the refrigerator and we would need to use (and possibly order additional, which had me a little worried) mechanical backup for the medical device. The utility company's web page indicated that the outage in our area was projected to last until 8:30am the next day, but they're usually pessimistic. Nevertheless, we had to plan for that.
So, we didn't watch television or listen to the stereo, but we did use the kitchen facilities (blender, seed grinder and lights, while opening and closing the refrigerator numerous times) to make smoothies. And we read and surfed.
I periodically checked the application for status to monitor our reserve capacity, and eventually, round 9:30pm (five hours later), the application indicated that the grid was back up, and the battery reserve was no longer in use.
If we had known that the outage would have been this "short," we may have streamed a movie on our big system or cooked a meal with electric appliances. But, we plan for the worst.
The outage depleted our 45% reserve to 32%. I was concerned that the following day, with extreme AC demand and cloudy weather, there would not be enough excess PV production to recharge the battery to the reserve threshold. However, as soon as the sun came up, all PV production was diverted by the energy gateway to the batteries, and when I got out of bed and checked, the capacity had already been replenished to 45%, and normal operation had resumed. I was impressed with the sophistication of this control algorithm, and overall, my expectations have been exceeded.
One problem that I see is that, whether we were at home or away, we may not have been aware that an outage was in progress and would have gone about running the AC and pool pump and charging the car, thus depleting the battery much more rapidly. We have to keep an eye on that. Since the application runs on a mobile device (not windows, unfortunately ... we had to acquire an android device specifically to run this application), we can monitor the system remotely and get home quickly if we need to.
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Comments
In a way I was sorry we were not home to get the benefit of the Powerwalls, but they did a great job at running the house for the 11 hours power was out.
I have no idea whether it will be implemented but even if they don't it gives one a warm feeling.
to 100 pecent each day?
I have my battery set to 10 percent reserve for backup. So far in about 1 year of use we've loss power 2x.
But in spring I probably will kick it up to 40 percent (T-storms and Tornado's).
I have 2 Tesla's and normal household loads. On an average day I usually export +30kw to the grid.
As many mention, the battery practically keeps me off the grid 24 / 7. Well worth the purchase price.
My solar system is approx 17kw with 16kw Sonnen battery. I might be adding 2nd battery next spring to
handle additional loads during normal solar downtime.
The Powerwall is similar in a way to the UPS units you are familiar with. A good UPS (all that I know of) is also a "line conditioner" which means it will use the internal battery and a combination of filters to ensure that a steady voltage reaches everything that is connected to it. Normally, grid power is always more "dirty" than what you will produce with a UPS or with the Powerwall, in that there are frequent fluctuations in the voltage. If your UPS has a voltage log you may notice that when you are on grid power, it is not always "123V" but there may be brownouts or spikes (small changes lower or higher than this voltage). The line conditioner function will use the system to keep a steady voltage however, and this is what your TV rep was talking about using for your TV to protect the system.
When you are on battery voltage from the powerwall it is not unusual to have 115V. The powerwalls are designed to run in a variety of voltage ranges and include filters and conditioners in the unit to ensure a pure and steady voltage/current. The voltage you see is also a function of some resistance drop from the battery source through your gateway and to your wall outlet, but should be very steady (like a UPS) so that there should not be significant fluctuations in voltage during powerwall use. Your UPS is beeping because you likely have it set to alert for certain low or high voltages, but this is not bad.
If you check the specs for your equipment, tv etc., usually in the manual or on the back of the power supply transformer, you will see specs such as "Input voltage" and "output voltage" etc. Input voltage for most electrical equipment will say something like 100-125V or 100-240V (i.e. international travel chargers). This means that the equipment will function normally with anywhere from 100V to 125V or 100V to 240V depending on what it says, so there will be no adverse effect if the voltage is 115 instead of 123V. I have not seen equipment that would not operate properly on 115V but would on 120V this is too small of a difference to matter, but look at the specs to be sure.
Enjoy! I myself am on the loooong waiting list for powerwall and I'm hoping to pair it with a solar roof on the new house I'm building (even longer wait). Its always nice to hear people's stories with their Tesla energy products, I can't wait till mine finally gets installed.
Our system is 7.4kW and is projected to provide 50% of our electricity annually if we make no changes, but with our new variable-speed pump, and other possible upgrades, we may do better. Obviously, we are not achieving off-grid-like performance. However, during the non-summer months (as recently as many days last May), we are able to charge the Powerwalls to 100% from PV and avoid using expensive onpeak grid power. During the summer months, with temperatures in PHX very high, the AC units run a lot more, so use of onpeak grid power is necessary, but minimized. In this case, we can maintain our reserve from PV, but cannot charge to 100% in a single day. (This overall performance is achieved using "self-powered" mode, as we do not have the TOU app upgrade yet.)
The result is that our most recent electric bill was half of what it was for this same period last year.
Coincidentally, we had another storm last night and lost power for three hours (second > hour outage this month!). My wife noticed the TV flicker and the app revealed that the grid was down. The backup system performed as expected, and we shut down non-essential appliances like in the previous outage but left a few more (LED) lights on.
Good advice about shutting down non-essential loads.
When yr pw’s are charged to 100% do they have enough reserve to supply yr off solar needs? I might look into adding another battery.
I charge both Tesla during peak solar production. 1 at a time. So far, I’m at 100% meeting my electrical needs. I keep a/c at comfortable setting. During a recent blackout I had neighborhood party at my house. Outside air temp’s over 110. My home only one with electricity and a/c. Transformer blew up and burnt the power pole. Outage was 5 hours.
My guess is that the demand of your house is exceeding the 5kW that a single powerwall can provide. You may have to do more planning for outages, such as triage the items that you need to power and shut down those that you don't.
In our case, if the outage occurred when we were charging our car and running the pool pump, the demand would likely exceed what the powerwalls can provide. Therefore, in an outage, I unplug the car and turn off the pool pump.
PS you asked for an expert to respond but I do not fall into that category just so you know. Good luck!
Help!!!!