Powershare update: Home Backup enabled for Solar + Backup Switch

[mongo]

One complaint I have though is that I can't prioritize where my solar power goes. It always goes to power the house first, the truck second, the powerwall third, and the grid last. I wish I could charge the powerwall before the truck as that makes more economic sense for my situation. The work around I have found for this is to limit the charge rate of my truck to about 2/3 of what my solar produces to force some into the powerwall.

Are you wanting time of use load shifting so that solar charges Powerwalls in the day and then Powerwalls run your home in the evening/ next morning? When do you want the truck to charge, and from grid or PW?

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[chaosmarine92]

Are you wanting time of use load shifting so that solar charges Powerwalls in the day and then Powerwalls run your home in the evening/ next morning? When do you want the truck to charge, and from grid or PW?

I want solar to charge the powerwall to full then charge the truck. Not the otherway around. It only takes a few hours to charge the powerwall on a sunny day vs a few days of sun to charge the truck.

 

[mongo]

I want solar to charge the powerwall to full then charge the truck. Not the otherway around. It only takes a few hours to charge the powerwall on a sunny day vs a few days of sun to charge the truck.

Right, I was trying to understand the "economic sense" part of your post. When is the energy from the Powerwall being used? (trying to manipulate available settings to achieve your goal without daily slider interaction)

 

[chaosmarine92]

Right, I was trying to understand the "economic sense" part of your post. When is the energy from the Powerwall being used? (trying to manipulate available settings to achieve your goal without daily slider interaction)

The powerwall powers my house in the evening/morning and can just about cover all my usual usage during that time. I'm fine with my truck taking a little longer to charge as i can minimize my grid usage that way. With it charging my truck first I end up using more power from the grid since my evenings/mornings are all grid power. Basically my truck usage is flexible and can shift around but my home usage is fixed.

 

[mongo]

The powerwall powers my house in the evening/morning and can just about cover all my usual usage during that time. I'm fine with my truck taking a little longer to charge as i can minimize my grid usage that way. With it charging my truck first I end up using more power from the grid since my evenings/mornings are all grid power. Basically my truck usage is flexible and can shift around but my home usage is fixed.

So it's a matter of matching overall energy usage to your solar production versus a day/night rate plan? Top up Powerwall on solar to carry house through the night, then charge with whatever solar is left, even if truck doesn't get fully charged?

 

[FlyShacker]

I was in your situation a couple months ago. I used my voucher from buying the truck to get the UWC and gateway 3V. Afterwards I decided to get solar plus battery installed. Come to find out from my installer that the gateway 3V I got is incompatible with solar and I need the gateway V3 instead. They also said the guts of both are nearly identical but the software on them is the main source of incompatibility.

Fast forward and now I have solar plus battery installed and running. But powershare from the truck is not available until there is a software update from Tesla. This update was supposed to come out by end of last year but now it's slated for sometime this year. Hopefully.

One thing to note, after my system was installed I couldn't configure my truck to use the charge on solar option for a couple weeks until my agreement with my utility was finalized for selling back excess power and I enabled the export power option on the app.

One complaint I have though is that I can't prioritize where my solar power goes. It always goes to power the house first, the truck second, the powerwall third, and the grid last. I wish I could charge the powerwall before the truck as that makes more economic sense for my situation. The work around I have found for this is to limit the charge rate of my truck to about 2/3 of what my solar produces to force some into the powerwall.

Very interesting. Thank you for chiming in. The priority scheme with your solar power in particular. Your workaround almost sounds like that was probably intentional in the design — throttling the charge rate of your truck. Is there any downside of doing that? Sounds very effective. I guess you also could pull the charger from your truck for a while to throw all the charge into your powerwall, but that takes a lot of manual intervention and monitoring. Anyway, it sounds like you are all set except for waiting for the Power Share update.

 

[chaosmarine92]

So it's a matter of matching overall energy usage to your solar production versus a day/night rate plan? Top up Powerwall on solar to carry house through the night, then charge with whatever solar is left, even if truck doesn't get fully charged?

That's essentially correct. I pay a flat rate all the time for usage and get a flat credit back for excess that is only 1/3 the import cost so it's better for me to maximize how much solar I use myself vs exporting it.

 

[chaosmarine92]

Very interesting. Thank you for chiming in. The priority scheme with your solar power in particular. Your workaround almost sounds like that was probably intentional in the design — throttling the charge rate of your truck. Is there any downside of doing that? Sounds very effective. I guess you also could pull the charger from your truck for a while to throw all the charge into your powerwall, but that takes a lot of manual intervention and monitoring. Anyway, it sounds like you are all set except for waiting for the Power Share update.

My workaround still feels cludgy and only really works for sunny days. If it's a little cloudy then I still end up putting nearly everything into the truck and only like 10-20% into the powerwall unless I limit the charge rate further.

Battery health wise I don't think there are any downsides to throttling the charge rate but charging efficiency wise the lower you go the worse your efficiency gets since there is a minimum amount around 600-800 watts that's used by the truck running the charging equipment. That's part of why level 1 changing is so slow, it's just barely over the minimum to actually charge. It's not a big deal in my case though as I throttle to around 5kw charging most of the time.

 

[mongo]

That's essentially correct. I pay a flat rate all the time for usage and get a flat credit back for excess that is only 1/3 the import cost so it's better for me to maximize how much solar I use myself vs exporting it.

Have you tried time based control?
Even though you are on a flat rate plan, this might provide the end result you want if the custom rate plan has the right settings.
Ugly way is switching Backup Reserve to 100% and back every day...

From Tesla docs:
With Time-Based Control, Powerwall stores energy when energy costs are low and may sell that low-cost energy back to the grid when energy costs are higher instead of using the excess solar energy for Charge on Solar. You may also see this behavior during virtual power plant or utility program events. In most cases, you will see the vehicle pause charging during Peak to prioritize total savings or charge your Powerwall from excess solar while charging your vehicle during Off-Peak from the grid.

 

[chaosmarine92]

Have you tried time based control?
Even though you are on a flat rate plan, this might provide the end result you want if the custom rate plan has the right settings.
Ugly way is switching Backup Reserve to 100% and back every day...

From Tesla docs:
With Time-Based Control, Powerwall stores energy when energy costs are low and may sell that low-cost energy back to the grid when energy costs are higher instead of using the excess solar energy for Charge on Solar. You may also see this behavior during virtual power plant or utility program events. In most cases, you will see the vehicle pause charging during Peak to prioritize total savings or charge your Powerwall from excess solar while charging your vehicle during Off-Peak from the grid.

I was initially set up on time based control with my flat rate set up and ran like that for a couple weeks before switching to self powered mode. I didn't notice any difference in behavior between the two. I haven't tried making a fake rate plan to trick it though. If it worked, which I'm not sure it would, wouldn't that throw off the cost savings calculation?

 

[mongo]

I was initially set up on time based control with my flat rate set up and ran like that for a couple weeks before switching to self powered mode. I didn't notice any difference in behavior between the two. I haven't tried making a fake rate plan to trick it though. If it worked, which I'm not sure it would, wouldn't that throw off the cost savings calculation?

Sure, putting fake numbers in to force behavior would mess up the readout. Is that an important factor?
Your real rate plan has no incentive to prioritize house load vs vehicle, but if it can be set to say daytime is high cost electricity and buyback is $0, then it might give you the behavior you want.

Self powered mode forces vehicle charging from the sun while running the house from the PW.

 

[chaosmarine92]

Sure, putting fake numbers in to force behavior would mess up the readout. Is that an important factor?
Your real rate plan has no incentive to prioritize house load vs vehicle, but if it can be set to say daytime is high cost electricity and buyback is $0, then it might give you the behavior you want.

Self powered mode forces vehicle charging from the sun while running the house from the PW.

Keeping the saving calculator accurate would be a nice to have.
I don't see how having high daytime cost with zero buyback would prioritize charging the powerwall, but maybe if I set the night time cost to be higher than daytime it would?

Edit: just tried switching to time based control with night being more expensive than day. It is rainy here so only a trickle of solar coming in right now. It started charging the powerwall at 5kw from the grid, which I don't want. I disabled grid charging and it is now using the trickle of solar to charge the powerwall and the grid to power the house. Also not ideal behavior.

 

[koolio]

I’m not sure why people are saying you need a backup switch if you have a Powerwall 3.

Based on Tesla’s documentation, it clearly says all you need is Wall Connector or UWC + Powerwall.

Also, this was the most recent post from @Cybertruck on X


So, the way it’s worded, I don’t see any need for a backup switch if you have Powerwall + WC gen 3 or UWC.

 

[mongo]

I’m not sure why people are saying you need a backup switch if you have a Powerwall 3.

Based on Tesla’s documentation, it clearly says all you need is Wall Connector or UWC + Powerwall.

Also, this was the most recent post from @Cybertruck on X


So, the way it’s worded, I don’t see any need for a backup switch if you have Powerwall + WC gen 3 or UWC.

The Powerwall 3 itself requires a Gateway or Backup Switch. It's inherent in the installation.

So, when adding Powershare to Powerwall, the only extra piece needed is the WC.

 

[mongo]

Keeping the saving calculator accurate would be a nice to have.
I don't see how having high daytime cost with zero buyback would prioritize charging the powerwall, but maybe if I set the night time cost to be higher than daytime it would?

Edit: just tried switching to time based control with night being more expensive than day. It is rainy here so only a trickle of solar coming in right now. It started charging the powerwall at 5kw from the grid, which I don't want. I disabled grid charging and it is now using the trickle of solar to charge the powerwall and the grid to power the house. Also not ideal behavior.

High daytime cost means it will charge Powerwall from the sun and wait to charge the vehicle until solar or the night rate kicks in.
A high night rate would make it want to charge the PW in the day on the lower rate.
The zero buyback is to prevent it charging from the "cheap" period and exporting during the "expensive" time.

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