When sizing your solar PV power system, you're going to need the following information at a minimum:

  1. The maximum power your load (the items you want to run on solar power) will draw at any instant - ie, how many Watts will be  needed if all items are on at once
  2. To do this you will need to check each item and determine what its power rating is and then add those power ratings together - you can usually find the power rating somewhere on the item, either as a reading in Watts (or kW) or in Amps (A). In the case of Amps, multiply the Amp rating by 230V to get the Watt rating
  3. An estimate of the number of hours (or part thereof) each appliance will be used each day 
  4. An estimate of the day/night power use split, eg. 40% day time 60% at night
  5. The type of roof you have (so we can quote on the correct panel mounts)
  6. The area in which you reside (this will affect the amount of energy the solar panels can produce)


To make things easier, we have developed a spreadsheet to assist you in calculating all of the above.

The spreadsheet contains many pre-populated appliances and loads with typical power ratings. NB: these power ratings are generic and may not apply to your specific items, they are there to serve only as a guideline and you may change them as you wish.



Use this handy spreadsheet to help you size your solar PV system:


If you don't have access to Excel then you can complete this form instead: