Welcome to Tesla Motors Club
Discuss Tesla's Model S, Model 3, Model X, Model Y, Cybertruck, Roadster and More.
Register

Powerwall drained…Sun is shining but nothing ?

This site may earn commission on affiliate links.
Howdy,

My first post here and I’ve done a bit of lurking and searching in this forum to see if there is an answer to this but no luck so here goes hopefully the wisdom of the internet will have an answer.

We have recently had a 8KW system installed with a Powerwall and gateway installed. Our primary rationale was resilience and we were particularly keen to ensure we would have a system that would continue to operate when the grid was down.

As luck would have it, 2 days after the system was installed Cyclone Gabrielle hit NZ and this knocked our grid offline for almost 50 hours. The powerwall had 50% capacity at the point the grid went down and throughout the day we gradually tracked downwards (whilst removing heavy loads to prolong the battery life) but eventually everything died and we were out of power till the grid came back on, which meant we were were without power for almost 2 days. What was frustrating to me was that the sun was shining outside and the Powerwall and inverter were dead and as soon as the grid came back on the inverter fired into life and started recharging the Powerwall, which implies that our system is still grid tied.

My expectation (perhaps misinformed!?) was that while the grid was down our PV system should have activated our inverter and started recharging the Powerwall and allowing us to start drawing an AC load from the Powerwall when sufficiently charged. This use case seems very reasonable to me and frankly rather important in a scenario where the grid goes down for an extended period of time so I’d like to figure out a solution. Here are some possible options :-

  1. This is a common use case and it should just work as you expected so the fact it didn’t means there is something wrong.
  2. Can the Powerwall be configured to never go to 0%, perhaps provide a 5% margin that can be used for the inverter to jump back into life (when the sun start shining) and start recharging the powerwall when sufficient PV power is available?
  3. Is there a way to jump start the Powerwall or gateway with an external power source to activate the PV/inverter?
  4. or if none of these can be made to work do I need to get a generator and wire it into the gateway so that it auto starts when the battery run down and the grid is disconnected?

Any other ideas ?
 
  • Like
Reactions: dhrivnak
Howdy,

My first post here and I’ve done a bit of lurking and searching in this forum to see if there is an answer to this but no luck so here goes hopefully the wisdom of the internet will have an answer.

We have recently had a 8KW system installed with a Powerwall and gateway installed. Our primary rationale was resilience and we were particularly keen to ensure we would have a system that would continue to operate when the grid was down.

As luck would have it, 2 days after the system was installed Cyclone Gabrielle hit NZ and this knocked our grid offline for almost 50 hours. The powerwall had 50% capacity at the point the grid went down and throughout the day we gradually tracked downwards (whilst removing heavy loads to prolong the battery life) but eventually everything died and we were out of power till the grid came back on, which meant we were were without power for almost 2 days. What was frustrating to me was that the sun was shining outside and the Powerwall and inverter were dead and as soon as the grid came back on the inverter fired into life and started recharging the Powerwall, which implies that our system is still grid tied.

My expectation (perhaps misinformed!?) was that while the grid was down our PV system should have activated our inverter and started recharging the Powerwall and allowing us to start drawing an AC load from the Powerwall when sufficiently charged. This use case seems very reasonable to me and frankly rather important in a scenario where the grid goes down for an extended period of time so I’d like to figure out a solution. Here are some possible options :-

  1. This is a common use case and it should just work as you expected so the fact it didn’t means there is something wrong.
  2. Can the Powerwall be configured to never go to 0%, perhaps provide a 5% margin that can be used for the inverter to jump back into life (when the sun start shining) and start recharging the powerwall when sufficient PV power is available?
  3. Is there a way to jump start the Powerwall or gateway with an external power source to activate the PV/inverter?
  4. or if none of these can be made to work do I need to get a generator and wire it into the gateway so that it auto starts when the battery run down and the grid is disconnected?

Any other ideas ?

It should have worked the way you describe, but if you have too much solar for the amount of powerwalls you have, you can end up in a situation where "the system" will not work.

Tesla recommends no more than 7kW PV per powerwall as far as I know, unless the system designer / installer does something to work around that. My guess is you had too much generation for one powerwall, so it wasnt starting, but thats just a guess. You should go back to your installer and ask them to troubleshoot it.
 
  • Like
Reactions: dhrivnak
The powerwalls are supposed to have a small reserve at the bottom end to be able to try to restart once there is sufficient solar to start charging them. However you need to turn off all the breakers to your home loads to allow them to do this. If they get too low to restart themselves there is also a procedure to jump start them by applying 12V to the gateway.

I'm assuming that when the power initially went out and the powerwalls were powering your house your inverters were still producing power but not enough to cover your usage. If they weren't producing any power even when there was sun that indicates an issue with your system.

 
  1. This is a common use case and it should just work as you expected so the fact it didn’t means there is something wrong.
  2. Can the Powerwall be configured to never go to 0%, perhaps provide a 5% margin that can be used for the inverter to jump back into life (when the sun start shining) and start recharging the powerwall when sufficient PV power is available?
  3. Is there a way to jump start the Powerwall or gateway with an external power source to activate the PV/inverter?
  4. or if none of these can be made to work do I need to get a generator and wire it into the gateway so that it auto starts when the battery run down and the grid is disconnected?

Any other ideas ?

1. This is a common use case and it should just work as you expected, provided you dont have an issue somewhere. The fact that it didnt means there is something wrong, somewhere, in the setup of your system.

2. Powerwalls do have a bottom buffer that is supposed to do what you say. Zero in the app is not supposed to be zero for the powerwall, and its supposed to try to start the system in the morning, if it runs out of power.

3. there are a couple of threads here on this although I havent had to do it myself. Here are a couple of links:


4.Some people who want ultra resiliency have both solar + powerwalls and a generator. We have a few different members here that have that setup currently. If you have an issue where you think this could happen more than "once in a lifetime" type events, and want more resiliency, then this is possible.

The generator wont charge the powerwalls, but can be configured such that they (powerwall+ solar and generator) never see each other, and you either manually or automatically switch on the generator if there is no solar + powerwall. In that instance, the solar + powerwalls basically become "the grid" for the generator, so the generator only comes on if there is no solar + powerwalls. I am not speaking from experience here though, just from information shared, so if this is wrong, those members who have more knowledge on this topic than me will correct me.