For the sake of example if you are getting 5 hours of direct sunlight per day in a sunny state like california you can calculate your solar panel output this way.
Amp hours from solar panel.
Then take the battery capacity which measured in ah and divide it by the amp rating the result from prior computation of the solar panel and then adding 10 of the charging time to it.
In a perfect world that you use 1 kwh per day.
5 hours x 290 watts an example wattage of a premium solar panel 1 450 watts hours or roughly 1 5 kilowatt hours kwh.
As you can see understanding the relationship between battery amp hours and the device or devices that you wish to power helps you determine how long to expect them to run.
At the end of this typical six hour solar day the panel will have generated 30 amp hours 5 amps x 6 hours 30 amps hours.
So the available 100 amp hours from the battery divided by 0 69 equals 145 hours.
For an analogy let s use some familiar automotive terms.
First you will have to determine the ampere per hour rating of the solar panel by dividing its power generation rating given in watts by the voltage of the battery.
10 watt 18 volt solar panel charging a 12v 10 amp hour lead acid battery 120 wh from 50 full to full time 60wh x 2 10 watts 12 hours.
For example if the solar panel is rated at 175 watts and the maximum power voltage vmp is given as 23 6 volts then calculate the current as 175 watts divided by 23 6 volts which is equal to.
To get that kilowatt hour back in your batteries your panels have to put in 100 amp hours from the sun before it sets.
One 100 watt solar panel in 10 hours of strong sunlight every day into your battery and you are self sufficient.
My 300 horsepower truck reached a top speed of 80 miles per hour during my 150 mile road trip.