A city with an average power consumption of 11, 000, 000 kWh per day would require roughly 11 million solar panels. Solar panel power ratings range from 250W to 450W, with 400W being the most popular power rating. If a town has limited roof space, 12 to 20 panels may be needed to. Calculate your perfect solar setup in 3 steps – more accurate than free online calculators. However, this estimate is for a “large. The number of solar panels needed for a city's power depends on factors such as location, weather, power usage, and available space. That's basically a 66×39 solar panel. But what is the wattage? That is unfortunately not listed at all. 60-cell solar panels are the standard solar panel size for homes.