Add up what you use in a day and this tells you how much solar and how much battery you need to keep up with it while boondocking.
Assumes flat-mounted panels and everyday losses from heat, wiring, and charging. Tilting panels or camping in full sun buys you margin.
How it works: panel watts = daily watt-hours / sun hours / 0.75 for system losses. Lead-acid banks are sized at double your daily use because draining them past half shortens their life; lithium can use most of its capacity.