Yes, a 400W solar panel can charge a 200Ah battery under ideal conditions. If you receive about 4~5 hours of sunlight daily, the panel could produce around 1600~2000Wh per day. It may take approximately 1.5 days to fully charge from empty but consider efficiency losses in your calculations.
[pdf] The Wind-Solar Storage-Charging System is a cutting-edge, integrated solution that combines solar and wind power with energy storage and charging infrastructure, enabling highly efficient energy use and optimized resource configuration.
[pdf] Faced with a variety of charging interfaces, voltage standards, and power output options, understanding the advantages and disadvantages of various outdoor charging methods —such as solar charging, car charging, portable power stations, and DC/AC inverters —can help you choose the most suitable and reliable off-grid power solution.
[pdf] 
