Power Consumption and Run Time

JASPak Solar Generator Power And Run Time

How much and how long? These are the 2 biggest questions anyone can ask.  The answer requires one more question – are you asking about run time during the night time with no solar power generation occurring, or is this during daylight when the 300 watt or 520 watt panel is providing power?

Daytime Use

During the daylight and sunshine, your 300 watt solar panel is generating power for your system, rated in watts.  This can be seen in the upper right corner of the solar charge controller on the JASPak Solar Generator lid.  This number will be constantly adjusting as sunlight conditions and charge requirements change.

Generally, while the sun is out and the panel is aimed into the sunlight, this number can read 200+ watts. That is what is going INTO the system, or being generated. If you are putting in 200+ watts and taking out 180 watts to run your refrigerator – you are actually generating more than you are using and the system is providing you power AND charging the battery. This is the most common scenario during daylight hours with the solar panel deployed.  You must be aware of your usage of power and the JASPak Solar Generator includes – AT NO EXTRA COST – a system status monitor to show show you real-time wattage usage so you know what is happening!

Nighttime Use

Now, let’s discuss what happens at night, when there is no power generation occurring and you are running on only the battery.  This is why you invested in the JASPak Solar Generator!  There is an enormous 153 Amp-Hour battery running this system and it WILL get you through the night!

The equipment that you want to run is rated in watts.  Almost all electronic equipment will have a tag or plate on it that specifically calls out the electrical specifications.  It will contain operating voltage, operating current and operating wattage.  If one of these components is missing, you can generally calculate the missing value with one of the following equations:

If you know the volts and amps, you can find the wattage by multiplying the volts times the amps – (120 volts * 2 amps = 240 watts)

If you know the volts and the watts, you can find the amperage by dividing the wattage by the voltage – (120 volts / 240 watts = 2 amps)

If you know the amps and the watts, you can find the voltage by dividing the wattage by the amperage – (240 watts / 2 amps = 120 volts)

So, that math works fine in an AC world, but what about when you complicate it with a DC battery power source and an inverter?  While it may sound like it should be complicated – it is as easy as this – for every 100 watts of AC power you need, you need 10 amps of power from the DC source (the battery) per hour plus 10% for inverter loss. You can learn more about battery amps and ratings in the Learning Center on the Batteries page

The easiest example to start with is the common 60 watt light bulb.  Here is how you forecast your power consumption when you are NOT USING THE SOLAR PANEL AT THE SAME TIME – This is for battery ONLY operation as may occur when there is no daylight and no solar energy available to put back into the system from the 300 watt panel:

  • 60 watt bulb + 10% to cover the inverter loss = 66 watts of AC needed from the inverter
  • 66 watts of AC is going to need 6.6 amps form the battery per hour
  • A 153 Amp-Hour battery to 50% DoD will be ~75 Amp-Hours (simplified for the sake of math)
  • If 50% DoD is not familiar to you, please read the Batteries page in the Learning Center to find out why we only get 75 amp-hours out of a 153 amp-hour battery.
  • 75 Amp-Hours (from the battery) / 6.6 Amp-Hours (for the light bulb) =  11.36 hours of run time for a 60 watt light bulb to 50% DoD.