Hi,
Can't comment on costs to install or run but usage is fab. I rented a place for 6 months before buying here and that had solar water.
It was amazing, everyday beautiful hot water, until there wasn't! we had 2 or 3 cloudy days and that does affect it. It was 300ltr tank which would normally be fine but I decided to have a big bath, 120 ltrs give or take just before the clouds came so following morning water hot but not as hot, day 2 water warm, day 3 water cold! This happened once in the 6 months so not really a problem. I was so impressed I'm going to look into putting one in when I renovate my new home. Good luck with everything.