A Solar Audio Classroom Sized from the Lesson Day: Battery and Panel for Six Hours of Spoken Lessons

Spoken lessons played to a whole class need only watts, but the storage must survive cloudy days. This paper sizes a battery and solar panel for six hours of daily playback at a stated speaker power, with two sunless days of reserve, and prices the system per pupil. The design is deliberately audio-only: adding a screen multiplies the energy budget and is costed in the discussion as the comparison a buyer should make. Computed results: daily_Wh = 30.0, battery_Wh = 70.6, panel_W = 8.9, system_cost_usd = 138.71, cost_per_pupil_usd = 3.47. Every number in this paper is produced by the accompanying script `compute.py`. SIMULATED, NOT MEASURED.