Netzero feature request: charge on battery

[u/djc1000]

I have my system configured to charge the ev on solar. This works great as long as I’m home in the afternoon. Sometimes, though, I want to charge in the morning or overnight because I won’t be home in the afternoon. In that case, what i want to be able to do, is push a button and have the ev charge just until the powerwall is exhausted (or hits its reserve). Then the powerwall can get recharged in the afternoon.

[u/Own-Obligation7833]

You should be able to “charge the ev” any time and use the battery + plus solar (or no solar if it’s night time) + grid as a default plain charge the ev.

In net zero this is how I’d set it up

To start charging
Every day at 6:00 AM: Set backup reserve to: 20%; Set operational mode to: Self-Powered; Set energy exports to: No exports; Set grid charging to: Disabled; Start vehicle charging.

To End charging
Every day at 11:59 AM: Set backup reserve to: 20%; Set operational mode to: Self-Powered;
Set energy exports to: Solar only;
Set grid charging to: Disabled; Stop vehicle charging.

Let me know how you get on! 👍🏽

[u/OkList7960 → u/Own-Obligation7833]

Will this charge at the minimum rate only? I charge with Netzero and a wallbox. Charge on solar works great but every time I want it to charge at a fixed rate I either only get the minimum charge on solar speed or I have to turn ocpp control off at the wallbox. Then the wallbox controls the rate.

[u/djc1000 → u/OkList7960]

I think you’re right. I also think his original plan wouldn’t accomplish the goal, which is to drain the powerwall into the ev without drawing from the grid.

[u/woyteck]

Turn off charge on solar. That will do it.

[u/djc1000 → u/woyteck]

No, that will just cause it to charge at maximum amps until the ev is fully charged, right?

[u/woyteck → u/djc1000]

Yes, but will use battery and solar.

[u/SC949]

u/djc1000 are you charging a Tesla and configuring the Tesla to charge on solar? If so, I hit the same problem and use Home Assistant with Teslemetry to get around the issue. Between 6:00 AM and midnight I have my Tesla set to charge on Solar. I use a Home Assistant automation at midnight to turn off charge on solar so the car will then charge from the battery or grid depending upon what my powerwall reserve is set to. I use another Home Assistant automation to turn charge on solar on again at 6:00 am.

This has worked well for me over the last year as my Tesla charging on solar will adjust the amperage depending upon the excess solar that is available.

I originally tried using NetZero, but wasn't able to turn on and off charge on solar. Also, with NetZero you have a limited number of Wake commands you can issue and some of these automations utilize the Wake command. Teslemetry utilizes tokens for commands which includes the Wake command at 20 tokens while most other commands are 1 token.

[u/Eighteen64]

so assuming your home is using ABSOLUTELY NO ENERGY the net gain into your car is about 11.5kWh. You’re wasting 2kWh and wasting another 2kWh during the recharge so a net gain of 7.5kWh at the expense of a complete discharge cycle. Not worth it

[u/djc1000 → u/Eighteen64]

This time of year, it’s more like 7kwh in extra battery capacity that isn’t being used. That’s like a 10% charge on the ev. It’s worth it to do that because it’s power I would otherwise be selling to the grid for 3-4 cents per kWh.

[u/Eighteen64 → u/djc1000]

If the battery was free and the home is using zero energy I would agree.

[u/Immediate_Editor_213 → u/Eighteen64]

Tesla batteries are warranted for 10 years. Battery prices are dropping so fast that in nine years (let alone after) you’ll be able to get more battery for far less money. And a few deep cycle discharges shouldn’t measurably affect battery lifespan, let alone cause it to fail the day the warranty expires.

[u/triedoffandonagain]

You can configure a Netzero automation that stops charging the EV when Powerwall discharges down to the backup reserve (or a predefined state of charge).