Stand Alone Power Systems (SAPS)


PLEASE NOTE: If you're considering home energy storage in a grid-connect situation; try our new solar + storage calculator!


Solar and battery system calculator


Determining your energy consumption


The load analysis tool below will assist you in analysing your load and calculating energy use. It lists power requirements (loads) of typical lights and appliances used in the various rooms of your house.


Appliances usually have a nameplate or sticker on the back, which has power consumption information. Correct power ratings (in watts) should be obtained from the nameplates or manufacturer’s literature, or by contacting the manufacturer.


The total energy consumed per day is calculated by multiplying the rating of the appliances by the number of hours that they are used. It is measured in watt-hours per day.



  1. Add ALL the appliances that you plan to power with this renewable energy system.
  2. If you are using a stand alone or off grid power system, tick all the AC appliances that will be used simultaneously.
  3. Choose whether you wish to use a generator to compensate for less sun in winter.
  4. If you get power from any additional sources enter them. eg, an alternator or wind turbine.
  5. Choose how many days of battery backup, and the battery depth of discharge you require.
  6. Click the "See Results" button located near the bottom of the page.

    Tip: 24 hours = 1440 mins, 12 hours = 720 mins, etc


Step 1: Add your appliances


Add an appliance


Optional Settings


Additional energy sources


Step 3: Generator


For home systems, we recommend that you have a generator as backup. Do you also wish to use a generator to compensate for less sun in winter?


TIP: Choose NO if you do not wish to use a generator. Choosing YES will mean you will use fewer solar panels, and will result in an lower up-front cost. Of course, generator running costs will eventually out-weigh the benefits of a cheaper up-front cost.


Step 4: Additional Energy Sources


Please enter the total number of kWh that is contributed by any additional sources (excluding the generator and battery charger). Eg. an alternator, micro-hydro, fuel cell or wind turbine. Leave it blank if you wish your system to be completely powered by solar power.



TIP: kWh = kilowatts × hours = (Watts × hours) ÷ 1000 = (Volts × Amps × hours) ÷ 1000


Step 5: Battery backup


The default values for number of days of autonomy and depth of discharge are standard, only change them if you understand what you are doing..


Choose number of days of autonomy: (Number of consecutive days of battery backup)


Choose % depth of battery discharge:


Step 6: Results & Recommendations