Sizing Solar Systems for RVs — What’s Different?

Load Calculation

When sizing a solar system for an RV, the first step is to calculate the total load or energy requirements. Start by identifying the essential appliances and their corresponding power consumption, such as the refrigerator, air conditioner, lights, and electrical devices. For example, a typical RV refrigerator might consume 50-75 watts, while an air conditioner could require 1,200-1,800 watts. Use a load calculation worksheet to determine the total daily energy requirements, taking into account both the peak and off-peak loads. A good rule of thumb is to assume a daily energy load of 1.5-2.5 kilowatt-hours (kWh) per day for a typical RV.

Panel Sizing

When selecting solar panels for an RV, consider using higher-wattage panels to maximize energy production while minimizing roof space requirements. For example, a 300-watt panel can produce more energy than four 75-watt panels, even though they occupy the same roof space. Choose a panel with an efficiency rating of at least 20% and a temperature coefficient of less than -0.5% per degree Celsius to ensure optimal performance in varying temperatures.

Battery and Inverter Sizing

Determine the required battery bank size based on the system’s daily energy load, the panel’s expected production, and the desired depth of discharge (DOD). For example, if the system requires 2 kWh of energy per day and the panels can produce 1 kWh per day, the battery bank should be sized to store at least 1 kWh of energy. Consider using a deep cycle battery with a high DOD rating to maximize storage capacity. For inverter sizing, select a unit that can handle the total load requirements, taking into account any startup surge current requirements for appliances like the air conditioner.