Solar systems can lose up to 25% efficiency due to dirty panels.

Don't waste your hard earned money on a solar system, then not make the most of the sun! 

Keep your panels clean and they'll perform much better.

You may have been told that your solar system required no maintenance, and that is generally true, but bird droppings, dust and especially resin from gum trees can seriously mess up your panels.

Ideally every 6 months or so (more often if they are getting very dirty faster than that), you should clean your solar panels.

Be very careful how you do this, do not attempt to clean the panels in the height of the day, when it is sunny and hot.  Many panels have glass on top and this is a great way to crack the glass.

Also, if you are going to get on the roof and clean them from up there, be extremely careful as roofs get very slippery when wet, especially tin roofs.

A safer alternative is to use a hose pipe from the ground, and direct it on to the panels, and if possible use a mop on the panels at the same time to shift the dirt.

If you go to you-tube you can find some great videos of cleaning solar panels, and it might give you some ideas of how you could do this.

The best option is to pay an expert to clean the panels for you, most states now have a solar panel cleaning service.  Some companies offer de-ionized water for cleaning, but they will tend to charge more.