Solar Power Estimate Calculator SPEC

Solar Power Estimate Calculator (SPEC) for caravans and other RVs

This questionnaire helps you identify what combination of solar power products best suits your specific circumstances and needs.

The calculator takes into account the power consumption you use in your caravan/RV and your travel destinations.

The SPEC is copyright © Solar 4 RVS 2014 so please read the copyright information below.

How to use the SPEC (Simple and Advanced)

There are 7 Sections (left to right and top to bottom):

  • Sections 1-6 will identify what system you need
  • Section 7 will let you input the wattage of panels you currently have/propose so you can see how long you can free-camp based on the battery capacity that you enter here.

​Some boxes require input whilst others automatically re-calculate:

  • If a box has a yellow background you can manually change the figure. It may have a pre-populated value which is a general assumption that is changeable.
  • If the box has a black background, the figure that appears has been automatically calculated.

Section 1: Power Consumption Data

From the drop down menu select battery voltage - 12V, 24V, 36V or 48V. Then enter either watts (column 1) OR Amps (Column 2) of items that will consume power plus the daily hours the item will generally be used (column 3). Column 5 lets you select whether the item is used day and night, just day or just night time. This section is pre-populated with some example data that should be checked and modified by the user for their specific needs.

Section 2: PV & Battery Performance Data

This section is pre-populated using real equipment data. The data, particularly the battery performance data should be checked and modified by the user if necessary. Enter how many hours you require the batteries to sustain your use, 24 to 72 hours is recommended depending on length of free-camping time and if back-up charging is available (i.e. a generator, DC-DC or a mains charger)

Advanced Only - Section 3: PV Solar Sizing Calculations

This section automatically calculates the required PV solar system size based on data in sections 1 and 2.

Advanced Only - Section 4: Battery Sizing Calculations

This section automatically calculates the required battery capacity based on data in sections 1 and 2.

Section 5: Select Location and Season

This section allows you to choose a location and season from the drop down menu. This may be a regular travel destination or area where you will use the solar power the most e.g. Tropical North Queensland in Australia’s winter (dry season up north). Once chosen, the location on the map will display the peak solar panel power, the solar charge controller capacity and the battery capacity required for that location.

Note: The map shows annual solar radiation levels from lowest (dark blue) to highest (red) across Australia. (Source:

Section 6: Calculation Results

This section displays your solar power system component requirements based on the data entered.

Advanced Only - Section 7: Current/Proposed system

Since the calculation results in section 6 are only a guide, this section gives you the opportunity to choose a smaller system. You just need to enter your current/proposed panel wattage and battery Ah. The automatic calculations then display how long you can be independent without mains power based on the amount/size of panels you have/propose and the battery capacity you have/propose.


Click here to launch SPEC Advanced

Click here to launch SPEC Simple

Please email through a screenshot to for a system quote.



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