If you are serious about installing solar PV panels you need to do your self a favour and check out the cost benefits of including a dual axis solar tracker as part of your installation provided you have the available room
The following web site is just one of those that sell and install these units and based on their claims you can get up to 40% more daily out put or alternatively reduce the number of panels installed for the same output.
I have a 5KW system installed on my roof and if I had adopted a dual axis solar tracker I would have got the same daily out put from just 3KW
Live and learn as they say
http://www.ecoforlife.com.au/solar_trackers.html
Cheers
Wobbly