Question: how to calculate your solar power requirements?
Answer: Solar panel watts x average hours of sunlight x 75% = daily watt-hours. As an example, let's say you have 250-watt solar panels and live in a place where you get 5 hours of sunlight per day. ... 
250 watts x 5 hours x .75 = 937.5 daily watt hours. ... 
937.5 / 1000 = 0.937.