✅ So, a 150Ah lithium battery or 250Ah AGM battery would be suitable. 5 peak sun hours/day in most of Australia): Solar Panel Wattage = Daily Wh ÷ Sun Hours 1490 Wh ÷ 5 hrs = 298W. I have enough solar panels to equal 160 actual watts of output in fairly bright sunlight. I also have a Xantrex controlled that can handle up to 60 amps of input current. How many deep cell batteries can I charge with this setup based on a very light load? How Much Do Solar Panels Cost? - How Can I. . My question is; how big of a battery do I need for a 160 Watt solar panel? A 1-to-1 Watts-to-Amp Hour ratio is about the maximum, with more wattage being preferred. 100ah would be a solid battery for that. Typically, this setup can provide adequate power for small appliances and electronics, 2. For the 400W setup: Panels can be wired in series (for higher voltage, lower current) or in parallel (better if. . To find the right battery size, convert watt-hours to amp-hours (Ah) using the formula: Battery Ah = (Total Wh ÷ Battery Voltage) Now consider depth of discharge (DoD) —most lithium batteries can safely discharge up to 80-90%, while AGM is about 50%.