# OPT-11 - battery modes, per battery

A battery's mode (on/off, Solar first, Leftover solar) is a soft unit limit at
`P_MODE` = 35 that always holds 0 W, applies only while the site target is
decided at or below 35, and is released by anything above it, such as the peak
guard. Design and owner answers: `goodwe-session/OPT-11-design.md` (2026-09-27);
P1 is its section 6 P1, and the pull request lists what was measured.

- Off by default (`battery_modes_enabled`); off, commands are byte-identical to
  a5dddad (`test_modes.py` part 1).
- Off is a mode range, so the peak guard can still use an Off battery (design
  sections 2-3). Whether Off should be absolute is an open owner question.
- In P1 only Off closes a direction; Leftover solar differs by charging last.
  Price runs, selling (`pack_sell`, reserved) and the forecast are P3/P4.