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Export/Import options for Self-powered

Export/Import options for Self-powered

The Tesla app allows Backup-only, Self-Powered and 2 Advanced modes. None of these allow you to automatically charge the battery at off-peak rates, power the house from the battery when needed, and export solar at peak exporting rates. To charge the battery you can manually set the Powerwall to Backup-only and then manually change it back to Advanced every day. Unfortunately, you cannot force the Powerwall to export excess solar, while still powering the house from the battery when needed, unless the battery is 100% charged.

It would be great if Tesla would add similar UI functionality of Peak and Off-peak in Advanced mode to Self-powered mode but with the options labelled as Import and Export.
If no Import/Export times are active then Self-powered will work exactly as it does currently.
If an Import time is active then the Powerwall will be charged from the grid and the house powered from the grid.
If an Export time is active then any excess solar power is exported to the grid rather than charging the Powerwall.

This should be fine with the power companies as grid power is not being arbitraged via the battery.
It is a relatively simple change for Tesla to make since all the base functionality is already in the app.

gregbrew | 2020年5月20日

"If an Import time is active then the Powerwall will be charged from the grid and the house powered from the grid."

Most utilities in the U.S.A. prohibits charging of the PWs from the grid, except during a weather-related emergency via the Stormwatch feature.

bb0tin | 2020年5月20日

In NZ we are fortunate that we can charge the Powerwall from the grid at any time. I expect that in the US the ability to export all excess solar to the grid when export prices are high, and power the house from the imported grid power when power prices are low, would still be useful. It is crazy that utilities would prevent charging the Powerwall from the grid since it is in their long term best interests to allow it.

gregbrew | 2020年5月21日

In SCE country (So. CA) the energy prices are so high, and the cost differentials between Times of Use are so large that you could make serious money using that differential by charging off-peak and discharging on-peak. Utilities don't want the competition.

bb0tin | 2020年5月22日

There are places where utilities do not prevent it (such as where I live in NZ), and some even encourage it. At the moment I have to actually switch off the Powerwall to export solar at peak demand times. Not only is this financially better for me but it also reduces the need for fossil fuel generation. It would benefit the owner, environment and grid if Tesla added this functionality. It is the Powerwall software which prevents the Powerwall from operating in the best manner rather than the utility. i.e. having a Powerwall makes exporting solar at peak times worse than not having a Powerwall. This is arse about face.

gregbrew | 2020年5月23日

I agree with you completely on how it *should* be done, but it's the local electrical energy utility that dictates how it's actually done, and their fealty is to the stockholders, not their customers or the environment.

Ain't capitalism grand?

bb0tin | 2020年5月23日

I understand that there are utilities in some places which prevent a Powerwall from exporting stored energy to the grid. However, I am unaware of a utility preventing solar being exported to the grid rather than charging the Powerwall. You simply need to turn the Powerwall off to make this happen. In NZ, there is no utility or regulatory reason to prevent what I suggest from being implemented. It is purely a lack of functionality from Tesla. This lack of functionality is causing more fossil fuel power to be produced than necessary. i.e. the Powerwall is acting to increase emissions rather than decrease them, which is the opposite of sustainable energy. I find that just crazy.

gregbrew | 2020年5月24日

I'm not aware of any prohibition the the States to disallow exporting solar-produced power to the grid, just from the battery.

There are utilities in the States that don't meter power pushed back out to the grid from any source. One such example installation has been described previously on this forum. This acts as a pretty strong disincentive to provide excess power back to the grid, but doesn't prohibit it. That would really suck to be providing uncompensated power to your neighbors, via the grid, and have the utility then bill them for it.

Tesla-David | 2020年5月24日

I live in Edmonds, WA and have exported on average >50% of our solar PV electricity back to grid over past 8 years. They pay us for the excess electricity ($0.54/kWh) which has helped us pay off the relatively hefty cost of our 2012 installation. This incentive amounts to a maximum of up to $5,000/year, but those incentives will sunset at the end of 2020. After that excess electricity exported will be banked against utility grid use during winter, when we do not produce enough electricity off our solar PV to cover our needs. We operate our two PW2's in self-powered mode and can operate independent of grid for 9 months of the year. No restrictions from our utility on exporting solar back to grid.

gregbrew | 2020年5月25日

SCE has offered net metering for decades, with a single "True-Up" bill each year. That sounds like what you'll be moving to. In SCE country, if your production exceeds consumption over the entire year, you're paid at the going wholesale rate, which hovers at $.02 - $.03 per kWh. It will be interesting to see what your utility pays for excess at True-Up.

If you consider that lifetime production costs for residential solar is usually somewhere between $.05 and $.10 per kWh, being paid wholesale is a losing proposition. Installing a too-large system has a negative ROI, and is yet another disincentive to doing so.