Project

Charging Shadowfax from the Dunster Wagon

The Dunster Wagon is our travel trailer, which I retrofitted to run 100% on solar. When we aren’t camping, its solar and batteries charge Shadowfax, my 2015 Tesla Model S 85D with Autopilot 1.0.

Shadowfax, a 2015 Tesla Model S, charging from the Dunster Wagon solar trailer — Shadowfax plugged into the Dunster Wagon at home

By the numbers

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2,650 W

Solar on the trailer roof

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15,187 kWh

Solar produced, Jan 1, 2022 to Oct 16, 2026

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3,468 miles

Driven on trailer solar alone, March–October 2024

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2,812 kWh

Charged into Shadowfax at home in 2024, per the Tesla app

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3,000 cycles

Rating of the Battle Born lithium batteries

The system

Everything runs through a Victron electrical system. Two Victron MultiPlus 3000 VA inverters, 2,400 W continuous each, turn the battery bank into 240 V power. That runs the trailer’s heat pump mini-split while camping. At home, the same 240 V output feeds the Tesla’s charger.

100% solar retrofit, built by me (finished late 2021)
2,650 W of panels
Battle Born batteries
2× Victron MultiPlus 3000 VA
240 V heat pump mini-split

Photos

The Dunster Wagon on the road and under construction — solar on the roof, Victron inside, Shadowfax on the charge cable at home.

The Dunster Wagon solar trailer parked by Utah Lake with snowy mountains behind — The Dunster Wagon at Utah Lake

Family camping with the Dunster Wagon solar trailer and Starlink in the desert — Desert camping with Starlink

Anthony Dunster lifting a large 530 watt solar panel onto the RV roof — Lifting the large 530 W solar panels onto the RV roof

Close look along the finished solar array on the Dunster Wagon roof — Finished roof array

Solar panels mounted on a unistrut rack on the Dunster Wagon roof — Panels on the unistrut rack

How the charging is automated

From 2022 I manually changed the Tesla charging amps daily. Since late August 2026, Grok Bot created an automation for me that automatically adjusts the amps my Tesla is pulling so that it matches the solar production. It reads the trailer’s data from Victron’s monitoring portal and controls the Tesla through TeslaFi.

Charging amps follow the solar coming in, so the car takes the sun reducing the charge cycles on the RV batteries.
When the trailer batteries are over 50% state of charge, the Tesla charges faster so the solar electricity always has somewhere to go. No electron wasted!
It stops charging once the trailer battery falls to a set floor, and it keeps a bigger reserve on cloudy days.
It stays off while we’re camping and works within TeslaFi’s monthly command limit.

Watch it

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