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Worked examples

Four real-world off-grid setups. Each link below opens the calculator with that design already loaded. You can change any input once it's open, and nothing gets saved unless you tap Save Current in the saved-designs panel.

These four sites cover very different climates: a tropical anchorage that stays clear most of the year, a cold high-latitude winter, a desert with plenty of sun but almost no roof space, and a northern New England homestead where wind makes up for the weak winter sun.

Caribbean sailboat

A 40-foot cruising catamaran anchored in the U.S. Virgin Islands. Roof space is tight (~300 W of flexible panels), but the tropical clearness index stays high year-round, so a 200 Ah AGM battery bank is enough to run the marine fridge, autopilot standby, chartplotter, VHF radio, and LED lighting overnight. It's a good example of how a small system in steady sun can outdo a bigger battery in a cloudier place.

Make the following input adjustments to see how the system is affected: bump panel watts to ~450 if you have a soft bimini you can add a flexible panel to, or drop the fridge duty cycle if you're under sail and water-cooled.

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Colorado cabin

A weekend cabin in the foothills above Golden, Colorado. The ~7,500 ft elevation and clear Mountain West sky mean strong harvest for most of the year, but cold and snowy winters push the panel tilt steep (50°) to favor low-angle winter sun. The 1.2 kW array and 200 Ah LiFePO4 battery system at 24 V are sized for a multi-day cloudy stretch in February, the worst-case month.

Make the following input adjustments to see how the system is affected: try switching Charge Controller from MPPT to PWM to see how a poor controller choice costs ~25% of harvest in a high-altitude install, where every Wh matters. Or drop the Solar Access fraction in December–February to model snow load on the panels.

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Phoenix van life

Roof area caps the panel array at ~400 W, but Phoenix's clearness index sits near 0.65 year-round so the small array pulls its weight every day. A 100 Ah LiFePO4 battery bank at 12 V buffers the vent fan running on summer afternoons and a brief induction-burner pulse for cooking.

Make the following input adjustments to see how the system is affected: the induction burner is a 1,500 W spike on a 15-minute duty cycle. Watch what happens to the inverter overload warning if you bump it to a full hour. This one is built to show the duty-cycle modeling.

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Vermont homestead

A year-round off-grid house in northern New England. Solar production drops significantly from November to February, right when the power demand (heat pump, longer lighting hours) goes up, so this design pairs a 3.2 kW solar array with a 600 W small-wind turbine on an 18-meter tower. The turbine covers the winter shortfall. A 400 Ah LiFePO4 battery bank at 48 V gives the whole house a buffer through a cloudy, windless week.

Make the following input adjustments to see how the system is affected: toggle the wind block off and watch the November and December rows go red. That's when the wind turbine outshines the sun. Or push the tower height from 18 m to 24 m to see the cubed-velocity scaling in the wind model.

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