Understanding seasonal cabin sizing
Why cabins size differently than full-time homes
A cabin using 2,500Wh a day with 4.5 peak sun hours needs about 694 watts of panel and roughly 520Ah of 12V battery to cover a 2-day cloudy buffer during a stay. That's often smaller than a comparable full-time home system, because the panels get weeks of unused sun between visits to fully recharge the bank, rather than needing to keep up with daily draw every single day of the year. The Department of Energy's homeowner's guide to going solar keeps the current program details, and it is worth a look before you decide.
The battery only has to cover your stay, not your absence
This is the single biggest mistake in seasonal cabin sizing: treating the days between visits as days the battery has to survive without recharging. In reality, a working charge controller keeps the battery topped off the entire time the cabin sits empty, so you should arrive to a full charge nearly every time. Size the battery around your longest realistic stay plus a cloudy day buffer, not around the weeks you're away.
Tree cover changes the math more than most cabin owners expect
Cabins in wooded settings across the Northeast, Upper Midwest, and much of Canada often lose 15% to 25% of potential output to partial shading from surrounding trees, even with a south-facing roof. If your site has any tree cover, use the lower end of the system loss factor options here, and consider the panel tilt for winter sun calculator if you use the cabin mainly in shoulder or winter seasons when the sun angle is lower. The seasonal production curve behind these estimates comes from NREL's PVWatts solar production calculator, and the seasonal output calculator by latitude in our performance and output tools breaks that curve down further by latitude.
Battery chemistry matters more for seasonal use
Lead-acid batteries slowly self-discharge and can sulfate if left sitting at low charge for extended periods, which is a real risk for a cabin visited only every few weeks. LFP batteries hold their charge far longer during idle stretches and tolerate sitting at full charge without the degradation lead-acid experiences, making them a better fit for infrequent-use properties even before factoring in their higher usable depth of discharge. The seasonal output calculator by latitude is the natural follow-up once this part is settled.
What to check once you have a system size
Once the wattage and battery numbers are set, match a controller to the panel array with the charge controller sizing tool, and look at the propane hybrid planning tool if you want a backup for extended winter stretches. A seasonal cabin can still qualify for federal credits, covered by the federal ITC calculator in our rebates and incentives tools, and the Department of Energy's homeowner's guide to going solar outlines the broader planning process from there. If you want to check this estimate against a second method, the quick 5-minute system size estimator in our System Sizing section works from your daily load and peak sun hours.