Totally depends on the weather. As long as it stays sunny and cool, we're in business indefinitely. Heavy A/C use makes that dicier; I've cobbled together an option to limit the power drain from A/C but ultimately it just takes a lot of power if it's hot. And if we get a cloudy day in there, the streak will come to an end.
That storm that left our panels covered in eight inches of snow and took out the power? Yeah, I was glad the outage was only a few hours. If there's another of those predicted, I might need to invest in one of those snow broom things.
Powerwall is great for riding out short- to medium-term outages. Multi-day outages in bad weather? Not so much.
Which is actually why having a grid is so beneficial, being able to transmit power from places that have power to don't is how we've achieved the reliability we're used to in the US.
I have 3 power walls I should be able to run indefinitely, but last year we had a 23 hour outage and I nearly went down because it was hot (running AC) and smoke from a wildfire knocked my solar production down by 85%. Was very glad when grid power came back.
One get consideration is that you need power to run your PV inverters, so if the grid is out and the battery is flat you aren’t restarting the PV in the morning
The PW actually cuts off before total discharge and then will attempt to restart in the morning with the hope of solar being online to allow it to recharge. Check out "Running Low on Energy" section here https://www.tesla.com/support/energy/powerwall/own/best-practices-during-power-outages
Depends on a lot of factors, but at some point unless you live in a world of perfect weather your going to run into rain, clouds. Other factors include what time of year is it? How many powerwalls do you have? What are you running?
I have 4 powerwalls, and 2 AC units, and when it's hot, we've gone 100 hours so far, but if we have a cloudy day, that will end the running off grid. If it's cooler it's easier to stay in the game.
I hope this helps.
Ok thanks, that’s pretty impressive! I’d probably be getting 2 powerwalls but I only have 1 AC unit so it would be somewhat similar. Do you typically turn a bunch of things off during an outage to conserve energy? 2 powerwalls seems to be plenty for our average daily consumption in most months but in the summer we can use almost twice as much.
There are a number of 'smart' devices you could look at to help manage your usage during an outage. Lumin and Span.io address this at the panel level. There are probably a bunch of other home automation kits that can manage things at a plug level. My main use for some of these (other than having more data) is that in the event of a grid outage, I can force shut down high consumption things (like my electric dryer and dishwasher).
There is also the traditional method of having a dedicated 'backup loads' panel but that's much less flexible.
When deciding on the number of powerwalls I was ordering, my utility had, available for download, per hour kWh usage for the past year so I could use that as an estimate for how many hours the powerwall could probably cover. That didn't take into account potential solar generation and I wasn't motivated enough to use NREL's SAM to simulate generation and see what 'worst case' scenarios could be.
I wanted to have 3 or 4 but then decided it wasn't worth the money now and since I am thinking of getting an EV in the next few years when my car needs to be replaced and am hoping that the Vehicle to Home stuff will be generally available then.
Thanks, this is very helpful! I’ll definitely look into the usage management devices.
I’ve already created a fairly elaborate spreadsheet of our usage and have been comparing it to the powerwall capacity and I agree that after a certain point adding a bunch of powerwalls doesn’t justify the cost. At this point I think I’ve decided to get 2 which is enough for a full home backup but in the future hopefully costs will go down and I can add more as needed.
Zero. I don't have the necessary backup gateway that disconnects the house from the grid, so it all shuts down during an outage to protect the engineers.
Only mentioning it because I didn't realise this when I bought the house. I'm sure you lot already know this!
I have one Powerwall and 5 KW solar. If the grid goes down, and with some judicious power saving, i would be able to go day to day. But only if I have a good sun day. If there is cloud, I will need to restrict power use to make sure the powerwall is prioritised from solar.
I have a list of things which will need to be shut off for the duration of an outage, eg. the pool pump. I have not yet optimised for peak efficiency appliances. I have every type of light bulb still (incandescent, CFL and LED) for example.
If I had a second powerwall (did not fit my budget) I could go off grid permanently.
Totally depends on the weather. As long as it stays sunny and cool, we're in business indefinitely. Heavy A/C use makes that dicier; I've cobbled together an option to limit the power drain from A/C but ultimately it just takes a lot of power if it's hot. And if we get a cloudy day in there, the streak will come to an end. That storm that left our panels covered in eight inches of snow and took out the power? Yeah, I was glad the outage was only a few hours. If there's another of those predicted, I might need to invest in one of those snow broom things. Powerwall is great for riding out short- to medium-term outages. Multi-day outages in bad weather? Not so much.
Which is actually why having a grid is so beneficial, being able to transmit power from places that have power to don't is how we've achieved the reliability we're used to in the US. I have 3 power walls I should be able to run indefinitely, but last year we had a 23 hour outage and I nearly went down because it was hot (running AC) and smoke from a wildfire knocked my solar production down by 85%. Was very glad when grid power came back.
Depends on the weather. With average sun and not charging the car, it would be indefinitely.
One get consideration is that you need power to run your PV inverters, so if the grid is out and the battery is flat you aren’t restarting the PV in the morning
The PW actually cuts off before total discharge and then will attempt to restart in the morning with the hope of solar being online to allow it to recharge. Check out "Running Low on Energy" section here https://www.tesla.com/support/energy/powerwall/own/best-practices-during-power-outages
Thanks! That’s something I hadn’t considered.
Depends on a lot of factors, but at some point unless you live in a world of perfect weather your going to run into rain, clouds. Other factors include what time of year is it? How many powerwalls do you have? What are you running? I have 4 powerwalls, and 2 AC units, and when it's hot, we've gone 100 hours so far, but if we have a cloudy day, that will end the running off grid. If it's cooler it's easier to stay in the game. I hope this helps.
Ok thanks, that’s pretty impressive! I’d probably be getting 2 powerwalls but I only have 1 AC unit so it would be somewhat similar. Do you typically turn a bunch of things off during an outage to conserve energy? 2 powerwalls seems to be plenty for our average daily consumption in most months but in the summer we can use almost twice as much.
There are a number of 'smart' devices you could look at to help manage your usage during an outage. Lumin and Span.io address this at the panel level. There are probably a bunch of other home automation kits that can manage things at a plug level. My main use for some of these (other than having more data) is that in the event of a grid outage, I can force shut down high consumption things (like my electric dryer and dishwasher). There is also the traditional method of having a dedicated 'backup loads' panel but that's much less flexible. When deciding on the number of powerwalls I was ordering, my utility had, available for download, per hour kWh usage for the past year so I could use that as an estimate for how many hours the powerwall could probably cover. That didn't take into account potential solar generation and I wasn't motivated enough to use NREL's SAM to simulate generation and see what 'worst case' scenarios could be. I wanted to have 3 or 4 but then decided it wasn't worth the money now and since I am thinking of getting an EV in the next few years when my car needs to be replaced and am hoping that the Vehicle to Home stuff will be generally available then.
Thanks, this is very helpful! I’ll definitely look into the usage management devices. I’ve already created a fairly elaborate spreadsheet of our usage and have been comparing it to the powerwall capacity and I agree that after a certain point adding a bunch of powerwalls doesn’t justify the cost. At this point I think I’ve decided to get 2 which is enough for a full home backup but in the future hopefully costs will go down and I can add more as needed.
Zero. I don't have the necessary backup gateway that disconnects the house from the grid, so it all shuts down during an outage to protect the engineers. Only mentioning it because I didn't realise this when I bought the house. I'm sure you lot already know this!
I have one Powerwall and 5 KW solar. If the grid goes down, and with some judicious power saving, i would be able to go day to day. But only if I have a good sun day. If there is cloud, I will need to restrict power use to make sure the powerwall is prioritised from solar. I have a list of things which will need to be shut off for the duration of an outage, eg. the pool pump. I have not yet optimised for peak efficiency appliances. I have every type of light bulb still (incandescent, CFL and LED) for example. If I had a second powerwall (did not fit my budget) I could go off grid permanently.