The number of solar panels needed for a van depends on several factors, including the energy consumption of the appliances and devices you plan to power, the available roof space on your van, the efficiency of the solar panels, etc.
On average, a single 100-watt solar panel like the Anker solar panel 625 can provide sufficient power for basic needs, but for more energy-intensive applications, such as running a refrigerator or powering multiple devices, you may need multiple panels or higher wattage panels. It's best to assess your power requirements and consult with a solar professional to determine the optimal number of solar panels for your specific solar panel van.