Questions on Outback SkyBox TOU and "Grid Zero" programming


New Member
Hi All,
I recently added an Outback SkyBox and a 5.3kWh LiFePO battery to my existing 4.6kW Enphase grid tied system. I have sorted out the AC coupling basics but have some questions on the best way to cycle the battery and effectively use the "Grid Zero" function. My short term goal is to use my AC coupled solar power in the mornings to charge the battery. Ultimately, I plan to add an additional string of panels to the SkyBox to make use of direct DC charging.

I am using the "Net Metering with Backup" profile to allow me to use my existing NEM agreement with PG&E and to provide the option of supplying critical loads and selected circuits for operating during a prolonged power outage or a planned power interruption.

From what I can tell from the user's manuals and experimenting with different AC coupling profiles, there is no simple way to set a schedule to discharge the battery and to initiate battery charging. With the "Grid Zero" mode active the system will use battery power if available to null energy usage from the grid. In the absence of DC coupled solar production, the system will use grid power to charge the battery when it passes into the lowest Time of Use energy rate window. In my case, my preference is to charge the battery during the morning hours when there is solar production and or "Off Peak" rates are in effect and prior to the "Partial Peak" rates period that starts at 12 noon. Using grid power, the system can easily charge a depleted battery in a couple of hours.

During productive solar hours my system is generally exporting power to PG&E and I can cover most domestic loads with the exception of charging my EV. The grid zero function typically starts in the late afternoon when solar production is tailing off and household loads are rising (electric oven, microwave, lighting, TV, etc..). I am not using the full depth of charge of my battery yet as I have not completely dialed in the charging protocol, but it can usually get through the evening and night hours before reaching the low battery voltage cut off.

So my question is if anyone out there is using a SkyBox with AC coupled battery storage in this same way to zero grid power usage? If so, have you found ways to create set points or use charging "windows" that work effectively? I am struggling with what I feel is poor product documentation regarding settings and thresholds, the complete actions of some "hidden" features as well as obtuse definitions for the system's battery charging protocol. I should add that I am using a battery that does not communicate with the SkyBox with a smart BMS. It has a BMS for protection against over or under voltage conditions, but no communication bus.

Any suggestions or direction to online reference materials would be appreciated.



Beefield, GA 30461
You need to email Outback support and ask them to setup a time they can call you to setup custom profiles. The questions will be; at what times does your Rate change? What is the lowest rate time, the highest rate time?
They will tell you that you need more panels charging and larger storage most likely, because your use hours are increasing as the rate does, but you can customize the charging peak time. Part of your issue will be your household environmental settings using a lot of power. Is there a 5-8 hour period daily your house is empty while the sun shines? The presets assume you work during the day so environmental setting can use less power. They will want access to 12 months of power bills in electronic format, so you can attach those to the support email request.

Use the Outback support forums to post this same question.
Make sure you have a userID and login to the forum. Registration is easy and help there is specific to your brand and locations too. My sympathy to you location of residence and your power source. You will get help though.

Hope this helps. If your house is never empty during the day they will tell you your needs are 24kWh battery with panels pushing twice capacity. They will advise washing and drying close at night during lowest rates, or hang laundry outside to dry in daylight hours as well as running AC less hours. Year house built? That will tell them insulation value. It will be adjusting your use hours and your capacity but they can setup custom charge hours.
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