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Estimating how many solar panels:

Solar panels harvest the energy from the sun.  There needs to be enough panels to meet your daily energy budget.  During summer there is around three times the amount of energy available compared to winter and so summer day time loads are generally not a problem.  Sizing a system comes down to calculating your winter load requirements.  A key factor will be whether you will use a generator or if you are willing to reduce your consumption during a rainy patch. 

First estimate your Average winter energy requirements using the calculator link on the "Living Off Grid" page.

If you are supplementing with a generator then the following list is a guide to how often you will need to run the generator.  Note that this is based on data from Manjimup with no shading.

Consumption = panel power x 1.2     Generator not required

Consumption = panel power x 1.4      Generator required 2 days per year

Consumption = panel power x 1.6      Generator required 7 days per year

Consumption = panel power x 1.8      Generator required 24 days per year

Consumption = panel power x 2.0     Generator required 46 days per year

If you are not supplementing your energy with a generator then calculate the minimum daily energy you are willing to live with  during a stormy 3 day period.  Check out the Tips on the 'Living Off Grid' page and click on the link to a useful online calculator.  Ensure that you factor in that the inverter will consume 20W of power continuously.

Note: Adding solar panels to your system to collect more energy on those cloudy winter days is generally more cost effective than adding batteries.

How they work:

They are made up of wafers of silicone called cells with 60 or 72 cells on a panel.  When operating, photons from the sun bump electrons from the top face to the bottom face and create around 0.56 volts between the top face and the bottom face.  Thin metallic finger like strips on the surface collect the electrons from the back and channel them to the top of the next cell where they are spread out over the surface by more thin, metallic finger like strips.  If one of the cells is shaded then electrons will not jump across that cell and the flow of electrons through the whole string will stop  - a bit like treading on a water hose.