Here is a quick crash course on how to calculate how quickly solar panels will charge batteries and how long a battery will last powering your devices.

If you have a 280 watt solar panel and a 12 volt 280AH battery, find out how many watts the battery can provide for a solid hour. The formula is 12 volts * 280AH = 3360 watts for 1 hour.

So if our battery can provide 3360 watts for 1 hour, it will take a 280 watt solar panel 12 hours of good sun to fully charge the battery. The formula is 3360 watts / 280 watts = 12. So you could take one 280 watt solar panel and charge our battery in 12 hours with good sun OR you could take twelve 280 watt solar panels and charge the battery in 1 hour.

How long will a 12 volt 280AH power a computer that uses 200 watts? Our battery can provide 3360 watts for an hour, so the formula to use is 3360 watts(for 1 hour) / 200 watts(what the pc uses) = 16.8 hours. So the battery can keep the computer power for 16.8 hours.

First, Solar panels only give they power they say under perfect laboratory conditions. A solar panel may give 370 watts in perfect laboratory conditions and will give less watts at average environment conditions. Then you may have more losses depending where on planet earth the panels are placed. Then you have clouds -_-

Also, inverters are not 100% effecient, and batteries don't capture 100% of the power they are charged with. So you have to account for these losses when designing your system.

In short, real life systems have energy losses so you'll have to figure out how much to buy to get what you need.