What Makes Up an RV Electrical System, and Where Does Solar Fit In?
Summary
An RV runs mainly on DC power stored in a leisure (house) battery. Solar is one way to refill that battery; shore power, the engine's alternator, and a generator are the others. Anything that needs household AC, 120 V in the US, runs through an inverter that converts the battery's DC.
Four ways to charge, one battery at the center
Victron Energy's September 2026 guide to RV electrical systems lists four charging routes.
- Shore power, a fixed mains hookup, charges the leisure battery and can feed high-wattage appliances directly, bypassing the battery.
- The alternator charges while the engine runs. Victron calls DC-DC chargers the only alternator-charging devices that can charge a lithium leisure battery, and the only way to smooth the fluctuating voltage of the smart alternators that began replacing standard ones around 2016.
- Solar panels turn sunlight into electricity through a charge controller that sits between the panels and the rest of the system. PWM controllers are cheap and suit small systems; MPPT controllers cost more and are much more efficient.
- A generator supplies AC, which works like shore power. Victron treats it as a last-ditch backup when solar and alternator charging cannot keep the batteries alive.
The starter battery is kept separate because it lacks the capacity to run campervan appliances.
Why 12 V is the default
The guide focuses on 12 V, which covers most RVs. It points to 24 V or 48 V when power consumption is high, when appliances are built for those voltages, or when cable runs are long, since a higher voltage lets you use thinner cable and voltage drop grows with distance. An inverter or inverter/charger handles the step from 12 V DC to 120 V or 230 V AC; the inverter/charger also charges from shore power and switches automatically between shore and battery.
Victron says each circuit should be protected by a fuse, with an isolation switch wired immediately downstream of the batteries.
Battery first, then solar
According to Victron, the size of a solar array depends on the leisure battery it charges and how quickly that battery needs to refill, and the capacity of every charging component is largely set by battery size. That is why the company sizes the battery first. On depth of discharge, it says lead-acid should go only to about 50% state of charge, and while lithium can handle going to 20% or even 0%, it recommends not regularly dropping lithium below 20%.
For the biggest loads, Victron's FAQ puts a microwave at around 800 to 1,000 W in short bursts and air conditioning at 1,200 to 2,000 W continuously. On shore power, those loads can run without drawing on the battery at all.
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Sources
- Victron Energy — Understanding the Components of Your RV Electrical System (September 3, 2026)
- Victron Energy — Recreational Vehicles (FAQ)
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