Off-grid, RV & cabin
Pick your cabin size and how often you use it. Get an instant ballpark solar and battery size, no load math required.
How it works Your inverter has to handle the biggest load you will run at once. The quick inverter size estimator in our Inverters & Equipment section can help you size it for your actual appliances.
Step 1
A rough size category, and whether you have a well pump, is enough for a ballpark.
Step 2
Weekend visits, seasonal stays, and full-time living have very different typical power needs.
Step 3
No load calculation required. Use this as a starting point, then run the full tools for a buying-ready number.
For weekend use, around 500 watts of solar and 300Ah of battery is a common starting point for a medium cabin with a well pump. For full-time living, that typically rises to about 1,500 watts and 900Ah, reflecting daily well pump cycling and continuous appliance use rather than occasional weekend loads. The DOE's solar photovoltaic technology basics has the current version, so check there before you rely on a summary.
A well pump draws several hundred watts every time it cycles to refill a pressure tank, and with regular daily water use, it cycles many times throughout the day. This adds up to a meaningful daily energy contribution that a cabin relying on hauled water or a gravity-fed system simply doesn't have, which is why cabin size in this tool specifically separates well-pump and no-well-pump categories.
This estimator leans on typical cabin usage for the size and use style you pick, but it can't account for an unusually large kitchen setup, heavy power tool use, or a well pump with an unusually deep draw. Someone with above-average appliance load should treat this estimate as a floor, not a ceiling, and build a full load list for anything beyond an initial ballpark. The quick 5-minute system size estimator picks up where this leaves off, using the figure you just found.
This quick estimator is meant for an early budgeting conversation or a fast sanity check, built on the same underlying production data as NREL's PVWatts solar calculator, which most solar sizing tools trace back to in some form. Before actually buying panels or batteries, run the off grid load list builder and panel count calculator with your specific appliances for a number that accounts for your actual cabin rather than a general category. The quick 5-minute system size estimator in our system sizing tools is a useful second opinion once you have a ballpark figure to check against.
If full-time or extended living is a realistic future goal even though you're weekend-only today, sizing the panel array toward that larger future target now can meaningfully reduce installation costs later. Battery capacity is comparatively easy to add incrementally as needs grow, while expanding a panel array and its associated wiring later is a bigger, more disruptive project. Federal tax treatment applies to off-grid cabin systems too, so it's worth checking the federal ITC calculator in our rebates and incentives tools before committing to a final budget, and DOE's solar photovoltaic technology basics is a solid starting point if you're still fuzzy on the fundamentals.
Questions
A quick estimate gives a reasonable ballpark for typical cabin usage patterns, but it can't account for a well pump beyond the general category, an unusually large kitchen setup, or heavy power tool use. Use the full load list builder and panel count calculator for a number you'll actually buy equipment against.
For weekend use, around 500 watts of solar and 300Ah of battery is a common starting point. For full-time living, that typically rises to about 1,500 watts and 900Ah, reflecting daily well pump cycling and continuous appliance use.
A well pump draws several hundred watts every time it cycles to refill a pressure tank, and it cycles throughout the day with regular water use. This adds up to a meaningful daily contribution that a cabin without running water simply doesn't have.
It depends on your plans. If full-time or extended living is a realistic future goal, sizing panels toward that target now can save on installation costs later, since batteries are easier to add incrementally than expanding a panel array and its wiring.