Power Export During TOU Peak Hours

[TheDon]

Hopefully a simple question for you all.
I am getting a 7.56kW solar and 2 PWs.

If I use either the balanced or cost savings on the powerwalls during the TOU peak times - does excess solar try to charge the powerwalls or go directly back to the grid? (Gaining peak time credits.)

 

[Silicon Desert]

Just out of curiosity, why are you buying powerwalls? Do you not have enough space on roof for additional West facing modules? Concerned about power outages? Are you in the LA area or San Diego area?

 

[Incredulocious]

Hopefully a simple question for you all.
I am getting a 7.56kW solar and 2 PWs.

If I use either the balanced or cost savings on the powerwalls during the TOU peak times - does excess solar try to charge the powerwalls or go directly back to the grid? (Gaining peak time credits.)

It goes back to the grid (preferring peak time credits) rather than charging the Powerwalls. Hence I switched back to Self-Powered so that it fully charges the Powerwalls before pushing excess back to the grid, thus allowing the Powerwalls to power the house completely overnight. It typically finishes charging the Powerwalls back to full by mid-afternoon or earlier anyway. (I’ve got about 9kW solar and 2 Powerwalls.)

Except in the winter (75% of the panels are oriented for summer afternoons) or we have some gloomy cold/rainy weather (and potentially running the heat pump) or the cars need significant charging, I can run 100% self-powered and still push excess solar back to the grid in the mid to late afternoons. (Sweet!)

Gray is grid usage (or export), blue is overall usage (solar+grid+Powerwalls):

 

[SoundDaTrumpet]

Hopefully a simple question for you all.
I am getting a 7.56kW solar and 2 PWs.

If I use either the balanced or cost savings on the powerwalls during the TOU peak times - does excess solar try to charge the powerwalls or go directly back to the grid? (Gaining peak time credits.)

@TheDon In cost savings mode, during the peak, there's no such thing as "excess" solar. The home is powered entirely by battery. All solar generation goes to grid (it does not go to the house, it does not go to charge the battery).

 

[aesculus]

And to expand on what @SoundDaTrumpet said it's even more confusing when you get to an end of a rate change period. So for example some of us are on a plan that has different time structures on weekdays vs weekend. So the PWs on Cost Savings mode monitor your use over time and when they get to Thursday or Friday they may decide not to even charge the PWs to 100% if they think they can get through that days peak period without reducing down to your reserve setting.

This works pretty well if everything is consistent but change your usage or have clouds and that model is destroyed. I have found myself running out of battery power near the end of peak. In that case you either pay your peak rates for the remainder of the period, or if you detect it, manually lower your reserve during that event to cover yourself.

BTW I have to do the same on certain holidays too since my plan uses the weekend rates for those too.

 

[getakey]

Someone on this board advised to eliminate Partial Peak in the App which makes the solar charge the PWs to 100% on Fridays. Works well. just move your Off Peak to go all the way to the Peak start time

 

[TheDon]

Just out of curiosity, why are you buying powerwalls? Do you not have enough space on roof for additional West facing modules? Concerned about power outages? Are you in the LA area or San Diego area?

The roof will have a lot of panels. We live in Southern Orange County by the mountains. We get a good number of power outages.

 

[bob_p]

A few weeks ago, we switched to a "Free Nights" plan (free electricity between 9PM to 9AM).

Our PowerWalls are set in "cost saving" mode.

During 9AM to 9PM, the solar panels and PowerWalls are used as much as possible to power the house.

From 9PM to 9AM, the system uses grid power for the house, unless it believes we will have excess power during the next day, when it will use some of the PowerWall power for the house during the "free nights" period.

So far - this has been working great. During the days, we're using .1 to .2 KWh of grid power, and on fully sunny days, we're putting 10-15 KWh of excess solar back to the grid (for free).

Last week, we used 1.4 KWh of power from the grid and sent back 83 KWh to the grid during daytime hours, which means we spent about $.30 on electricity last week, everything else was either from the sun or during free nights. We did "waste" 83 KWh sent back to the grid, but it's hard to complain about that, since we're essentially running on free energy...

At least until the utility companies decide to exclude homes with battery storage from their free nights plans...