We've had a similar system (Hills Solar) for a couple of years. They're both evacuated tube technology so hopefully my comments are relevant. Our system is unbelievably efficient. We have a manual switch for electric boost and we only use it for 1-2 hours about 5 times year. There are number of factors which make it work well.
- ensure mounting at latitude + 10 degrees (up from horizontal) to maximise winter efficiency. Summer will take care of itself
- don't be tempted to go too big on the storage tank. We have 4 people and a 250 litre tank. New systems have to have cold mixed with the output anyway so your 250 litres goes further. If you go for too big a tank, it struggles to get up to temp. This obviously depends on how many tubes you have. We have 30 tubes and live at 900m altitude outside of Canberra, so it's a reasonably taxing climate
- don't wire it into off-peak electricity; it will just come on at night using lots of power. You will, however, have lots of hot water, but at a price
- no shade ever hits our tubes from dawn until dusk
