First post! I’m deciding on the settings of my new (December 2019) system. I have 6.6kw of PV and 2 Powerwalls that charge from solar only.
My utility has old-school net metering, with a 1-to-1 credit for excess production. Utility power costs the same all day and night. So there’s no electric-bill incentive to use the battery instead of the grid until one of those factors changes.
My primary purpose for the Powerwalls is as a backup – I live in a storm-prone area with frequent short outages from thunderstorms and multi-day outages every few years from tropical systems. (FWIW, a generator wasn’t an option for various reasons.)
So what is my best setting? I’m concerned that backup-only mode will keep the PW’s at 100%, shortening their useful lifespans. I’m also concerned that using self-powered mode will mean losing 10-15% with each charge and discharge thus wasting money. Is there any benefit to switching between self-powered and backup-only, so the battery is getting charged and discharged? Or do charge/discharge cycles shorten battery life?
My utility has old-school net metering, with a 1-to-1 credit for excess production. Utility power costs the same all day and night. So there’s no electric-bill incentive to use the battery instead of the grid until one of those factors changes.
My primary purpose for the Powerwalls is as a backup – I live in a storm-prone area with frequent short outages from thunderstorms and multi-day outages every few years from tropical systems. (FWIW, a generator wasn’t an option for various reasons.)
So what is my best setting? I’m concerned that backup-only mode will keep the PW’s at 100%, shortening their useful lifespans. I’m also concerned that using self-powered mode will mean losing 10-15% with each charge and discharge thus wasting money. Is there any benefit to switching between self-powered and backup-only, so the battery is getting charged and discharged? Or do charge/discharge cycles shorten battery life?