solar system comparison

This calculator will compare up to two solar generator systems by calculating how long you can run appliances WITHOUT SUN, as well as calculating recharge times, efficiency and more.

There are three steps to this calculator.

1- Choose up to two systems to compare.

2- Enter all appliances and tools you will be running in an emergency situation.  Usually this means critical things, like a fridge or freezer, or maybe even a gas furnace.

3- Click the “Calculate!” button to calculate the results for the systems.

Step 1: Choose systems to compare.

System #1



System #2



Step 2: Choose what you will run.

Power Usage:
















  Step 3: Calculate the results.

Remember to recalculate after any changes!

  System #1

  System #2

              Solar Generator
Run Time = The amount of time in hours the system
will run without any sun. For critical loads such a
refrigerators, freezers, furnace, etc. This time should
be at least 48 hours to last through stormy weather.

Recharge Time = The time in hours to recharge your
batteries if fully drained to there maximum level of

System Efficiency = The average of several effiecinecy
measurements. Anything over 70 Is extremely good.
Anything under 50 is poor, and you should consider
a different system for your application.

Cost per hour runtime = The amount in dollars it will
cost you for each hour of Run Time you have.

System results are calculated from manufacturers reported
information. To see This data, click here

* Actual charge times will vary depending on outside temperature, type of batteries, and other variables. However this is a good approximation, and much more realistic than other charge times you will see, because it takes into account solar panel size, battery size,max DOD of battery bank, as well as the tow phases of charging (Bulk, Absorption). Float charge time is not calculated in, because it can range from 0 to 12 hours depending on the type of battery. However after the absorption charge your batteries are nearly full.
In order to maintain long battery life you should allow for a good float time often, unless your battery bank is lithium, then you do not need to float charge your batteries.
Appliances Watts Appliances Watts Appliances/Tools Watts
Oven 3,000 Standard TV 188 Well Pump 1/3 hp 750 (Running) 1400-3000 (Starting)
20 cu. ft. (AC)
16 cu. ft. (AC)

1411 watt-hours/day* 1200 watt-hourrs/day*
LCD Monitor 80-150 Well Pump 1/2 hp 1000 (Running) 2100-4000 (Starting)
15 cu. ft. (Up)
15 cu. ft. (Chest)

1240 watt-hours/day* 1080 watt-hrs/day*
Desktop Computer (Standard) 80-120 Sump Pump 1/3 hp 800 (Running) 1300-2900 (Starting)
Dishwasher 1200-1500 Desktop Computer (Gaming) 400-1000+ Sump Pump 1/2 hp 1050 (Running) 2150-4100 (Starting)
Electric Clothes Dryer 3,400 Laptop Computer 40-120 Drill (1/4"-1/2") 250-1000
Gas Clothes Dryer 300-400 Clock Radio 7 9” disc sander 1200
Washing Machine 500-1000 Plasma TV 339 3” belt sander 1000
Microwave 1,500 LCD TV 213 12” chain saw 1100
Toaster oven 1,200 iPad / Tablet 10-20 14” band saw 1100
Hot Plate 1,500 Satellite dish 30 Circular Saw 1400-1800
Electric Skillet 1000-1500 Cell Phone - recharge 2-10 Jig Saw 300-700
Toaster 1,100 Radiotelephone - Transmit 40-150 Chop / Cut Off Saw 1500-1800
Coffee Machine 1,500 Radiotelephone - Receive 5 210 MIG Welder 6,500
Blender 300-1,500 100 watt incandescent bulb 100 Air Compressor 1 hp 2000
Vacuum Cleaner 500 50 watt DC incandescent 50 Central Air Conditioner 1000-1500 (Running) 2200-5000 (Starting)
Dehumidifier 350 25 watt compact fluor. bulb 28 Room Air Conditioner 1,100
Humidifier 300-1000 20 watt DC compact fluor. 22 Furnace Blower 300-1000
Portable Fan 100 CFL Bulb (60-watt equivalent) 18 Portable Heater 1500
Ceiling Fan 100 CFL Bulb (100-watt equivalent) 30 Stock Tank Heater 100
Curling Iron 90 Electric blanket 200 Garage door opener 350
Hair Dryer 1,538 Water Heater 479 Shop Vac 6.5 hp 1440

* TV’s, computers, VCR’s, and other devices left plugged in, but not turned on, still draw power.

**To estimate the number of hours that a refrigerator actually operates at its maximum wattage, divide the total time the refrigerator is plugged in by three. Refrigerators, although turned “on” all the time, actually cycle on and off as needed to maintain interior temperatures.