Size your whole system
Filled in from your van setup in Oregon, recalculated just now. Change anything below.
Your daily use and your darkest month decide everything. Put them in and you'll get panels, batteries and an inverter, plus a cost range.
Oregon gets about 1.1 hours of strong sun a day on panels lying flat on a roof in December, its darkest month (NASA data).
| 4 | Solar panels, 200 W0.8 kW total — about as many as fit. In winter, top up by driving (a DC-DC charger) or a small generator |
| 5 | 12V 100Ah lithium batteries6.0 kWh stored · about 1.2 kWh usable each |
| 1 | Victron MultiPlus-II + MPPTRuns everything you plug in |
In your darkest weeks the sun doesn't quite keep up, so the batteries end each day a little lower. A charger that tops up while you drive covers the gap.
In summer they're full again by 3pm, and the extra sun is yours to use.
Starting full at 6pm, the batteries run the night, drop to their lowest around 2pm (0%), then the panels make about 0.7 kWh a day in your darkest month against about 4.0 kWh used. After two days they sit at 0%.
Rough one-time cost: $8,000 – $10,000, parts and wiring.
Go deeper: how this works
Panels: daily use ÷ darkest-month sun hours ÷ 0.77 (wires, heat, dust) × 1.1 (margin).
4.0 ÷ 1.1 ÷ 0.77 × 1.1 = 5.1 kWBatteries: daily use × days without sun ÷ usable storage per battery.
4.0 × 1.5 ÷ 1.2 = 5Want it done for your life?
The guides ask how you live instead of how many kWh, then size everything and show the exact picks.