Off-Grid Solar Calculators

Solar panels

Off-Grid Cabin Daily Solar Need

A small cabin budget is just watts × hours for each load. Measure or look up real wattage; nameplate motors are often far above average draw.

Inputs

W

Average running watts, not the compressor surge.

h
W
h
W
h
W
h
Wh

Results

Fridge energy
400Wh
Lights energy
100Wh
Electronics energy
160Wh
Pump energy
100Wh
Total daily energy
860Wh

Recommended gear

Engineering methodology

Energy for each load is watts × hours (Wh = P × t). Daily total is the sum of fridge, lights, electronics, pump and any extra watt-hours. Nameplate motor watts are not the same as average draw. Feed the total into the solar array and battery-bank calculators.

Frequently asked questions

Should I use nameplate watts or a measured average for a cabin fridge?

Use average running watts times hours (or a duty cycle). A compressor’s nameplate is closer to running watts, not the start surge, and the compressor is not on 24 hours a day.

How do I turn this daily Wh total into panels and batteries?

Use the solar array sizer (daily Wh, peak sun hours, derate) and the battery bank sizer (daily Wh, days of autonomy, DoD). This page is only an energy budget.

Why can a water pump dominate a small cabin budget?

Watts × hours: a 200 W pump for 0.5 h is 100 Wh, similar to LED lighting all evening. Surge for the pump is a separate inverter problem and is not included in this sum.

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