There is really no reason to even consider getting a solar energy system if you live in an area that rarely sees the sun. This does not mean that a less than reputable company will not try to sell you a solar system though. If your roof does not receive at least 6 hours of full sunlight per day, you should not consider solar power.
One of the greatest benefits of solar energy is the fact that it will never run out. Short of the sun burning out, it will always be there to provide us power. Using solar energy is unlike any other energy source because it is a consistent power source and will be there until the end of days.
Heliocol customer Keith Gascoine in Tallebudgera, QLD reviews his happy experience using Heliocol solar pool heating.
Be realistic about the costs of having a solar energy system. If you're paying much less than other systems that are around the same size as yours, you may have poor equipment or installation work. Like with many things in life you get what you pay for. Quality installation work and equipment isn't going to be cheap. You may have substantial savings by going with a large company, but other companies may be cutting corners to keep costs down.
Before installing any form of solar panels, be familiar with local rules and regulations. There are lots of places where some permits are required. The last thing you want is to have the system put it and then you are forced to remove it later.