To do this, get your last 12 monthly power bills and calculate your average kilowatt hour (kWh) usage per month. The reason we use 12 is because our power consumption fluctuates with the seasons. The calculation would be to add up the power used over the past 12 months and divide it by 12. But if you do not have all your power bills, then simply use last month’s one.

Now take your average monthly usage and divide it by 30 to work out your average daily power consumption.  Read More...

Before you can work this out, you need to find out how many usable hours of sunlight your region gets per day. A simple way to find that out is to have a look at an insolation map - you could just google it to find one.

Now take the average daily kWh calculation and divide that by the number of daily usable sunlight hours, then multiply that by 1.25 (to take into account the wasted energy from wiring, charge controllers. batteries, and inverters).  Read More...