Tesla Powerwall 2 - Solar generation during power cuf

Qyburn

Hi,

This is a question for anyone with a Powerwall 2, configured for backup during power cuts. Does your solar inverter work and charge the battery in this state, if so then what inverter do you have?

I guess the same for installations where it doesn't work, it would be worth knowing which inverter types to avoid.

Tesla documentation says that it should work with "most" inverters, but the local installer says not.

NigeWick

It's the gateway that allows us to go off grid, I don't believe the inverter matters as it readily accepted whatever mine is. 

The system gets information and the battery will top itself up if there's a storm forecast. Surprised me the first time I saw it.

Qyburn

Thanks. To be clear can you confirm that your inverter still works to charge the battery from solar while it's disconnected from the grid during a power cut?

If so what happens when the battery's fully charged? 

[Deleted User]

Qyburn said:

Thanks. To be clear can you confirm that your inverter still works to charge the battery from solar while it's disconnected from the grid during a power cut?

If so what happens when the battery's fully charged? 

It works as described here:

How Powerwall Provides Backup Power

When a utility power outage does occur, your Powerwall instantly disconnects from the grid and restores backup power to your home in a fraction of a second, over one hundred times faster than typical standby generators. This means your appliances keep running without interruption, and there’s no need to reset your clocks. You may not even notice when an outage occurs. Learn more about what Powerwall backs up.

If you have solar, your Powerwall can recharge from your solar system to run your home from solar and Powerwall even when the grid is down. A traditional solar system without a Powerwall does not function during a grid outage.

If more solar energy is produced than can be used or stored during an outage, Powerwall will turn off the solar system and turn it back on when the energy can be used again.

Qyburn

Dolor said:

It works as described here:

If more solar energy is produced than can be used or stored during an outage, Powerwall will turn off the solar system and turn it back on when the energy can be used again.

Thanks. I saw that in Tesla documentation, but it isn't clear whether this requires some specific signalling or connection between PW and the solar inverter, or whether it's more passive like the inverter responding to frequency or voltage rise.

Just a little vent, I'm having real trouble getting detail from any of the installers, they seem to work on the basis of expecting us to give the go ahead first, then sort out the practicalities later.

pete-20-11

Qyburn said:

Dolor said:

It works as described here:

If more solar energy is produced than can be used or stored during an outage, Powerwall will turn off the solar system and turn it back on when the energy can be used again.

Thanks. I saw that in Tesla documentation, but it isn't clear whether this requires some specific signalling or connection between PW and the solar inverter, or whether it's more passive like the inverter responding to frequency or voltage rise.

Just a little vent, I'm having real trouble getting detail from any of the installers, they seem to work on the basis of expecting us to give the go ahead first, then sort out the practicalities later.

It increases the frequency which causes the solar inverter to stop generating 

Grandad2b

pete-20-11 said:

Qyburn said:

Dolor said:

It works as described here:

If more solar energy is produced than can be used or stored during an outage, Powerwall will turn off the solar system and turn it back on when the energy can be used again.

Thanks. I saw that in Tesla documentation, but it isn't clear whether this requires some specific signalling or connection between PW and the solar inverter, or whether it's more passive like the inverter responding to frequency or voltage rise.

Just a little vent, I'm having real trouble getting detail from any of the installers, they seem to work on the basis of expecting us to give the go ahead first, then sort out the practicalities later.

It increases the frequency which causes the solar inverter to stop generating 

Pedant alert: I wasn't aware that the inverter did any generating. Perhaps you'd be good enough to explain what you mean.

Martyn1981

To prevent SSEG's (small scale embedded generation) from pushing the grid voltage and frequency too high, when there's a lot of generation (and export), and not enough demand, inverters will shut down. For instance if grid voltage reaches 253V, the inverter should shutdown, and monitor the situation, before restarting.

So from what Pete says, it sounds like that's the way generation is controlled/managed in this situation, when the battery is full.

pete-20-11

Grandad2b said:

pete-20-11 said:

Qyburn said:

Dolor said:

It works as described here:

If more solar energy is produced than can be used or stored during an outage, Powerwall will turn off the solar system and turn it back on when the energy can be used again.

Thanks. I saw that in Tesla documentation, but it isn't clear whether this requires some specific signalling or connection between PW and the solar inverter, or whether it's more passive like the inverter responding to frequency or voltage rise.

Just a little vent, I'm having real trouble getting detail from any of the installers, they seem to work on the basis of expecting us to give the go ahead first, then sort out the practicalities later.

It increases the frequency which causes the solar inverter to stop generating 

Pedant alert: I wasn't aware that the inverter did any generating. Perhaps you'd be good enough to explain what you mean.

Okay, so it stops the inverter from inverting. 😆

basically stops the solar inverter from doing its job. 

Inverters are designed to stop generation from the panels being sent to the house or grid if the voltage and/or frequency is outside of the allowed range. The Tesla power wall is taking advantage of that design to control/stop the solar generation.