Sizing a Solar Generator for 200 Watts

How Long Will a 200-watt Solar Generator Run an Appliance?

Electrical energy is measured in watt-hours, which is calculated by multiplying the wattage of the device by the number of hours it will be used.  For example, if you have a 60 watt laptop and want to use it for 2 hours, you will need 120 watt-hours (Wh) of energy.

If you like to calculate the working times for an appliance on a solar generator you use the following formula:

Working Time =  Solar Generator Watt-hours x 0.85/ operating power of the device 

You’ll multiply the Watt-hours of the device by 0.85 because of system losses. This is due to the wiring, DC-AC conversion, and efficiency losses. 

For example to get the working time for a 60-watt laptop

= (200 x 0.85)/60 

=  2.88 hrs

So 200 Watt-hours is enough to run a 60w laptop for 2 hrs 49 minutes

Appliance (Wattage)Runtime/Charges
Light 10W20 Charges
Phone 15W12 charges
Car Fridge 30W5 hrs
Laptop 60W2hrs+

How Long will the 200-watt solar generator last with a Solar Panel?

The recommended solar panel for a 200-watt solar generator is a 50w solar panel.  This solar panel can charge the battery in around four hours. This will depend on the availability of sunlight. 4 hours of sunlight in an ideal situation should provide 400Wh enough to recharge the solar generator.

With the solar panel you have extra 50-watts going to the solar generator adds to the capacity of the solar generator.  A solar generator that supports pass-through charging will enable you to use it as you are charging. 

With a 50-watt solar panel hooked on the solar generator you can run a 50-watt appliance without depleting the capacity of the solar generator.  You can also run an appliance like the laptop for longer periods.