Solar Hot Water Research

I attended the [Gerringong solar hot water information night](http://green-change.com/2008/11/19/solar-hot-water-information-night-gerringong/) on Friday. It was very well-run, and was a great opportunity to talk to lots of different suppliers all in one place.

The presentation by [Jamberoo FutureCare](http://jamberoofuturecare.googlepages.com/) was excellent. They don’t have any particular axe to grind – they just want to present the facts and help people choose a hot water system that suits them. This made the presentation way more valuable and trustworthy than if the talk had been by any other group (e.g. a supplier, the Council, an electricity or gas company, etc).

The night was also a great opportunity to meet like-minded local people. I met Sarah and Roger from Jamberoo FutureCare, and also met up with a few other friends from around town who I hadn’t seen for a while.

Several of the suppliers I talked to expressed an interest in holding a similar night in Wollongong, so hopefully that goes ahead.

I was hoping to find some kind of retrofit for our off-peak electric hot water system. What I had in mind was a small solar panel that would pre-heat the incoming water for our system. It wouldn’t require a pump or anything complicated, just using mains pressure to get the water to the roof. Heating the water before it enters the system should save all the energy needed to raise cold water to 60 or 70 degrees. From what I can tell, something like this should cost under $1000. Sadly, it appears there is nothing like this available on the market. Perhaps there’s an opportunity there for an entrepreneur?!

So, my options are to retrofit solar to my existing tank, or to buy a complete replacement system.

Retrofitting involves installing the solar panels or evacuated tubes, and then installing a pump near the existing tank to circulate water to the roof and back to keep it hot. So the only saving over a full split system is the cost of the tank. Unfortunately, some of the government rebates are not available if you don’t buy a tank, so doing this actually ends up costing more than a complete replacement! One estimate I got was for about $2500-$3000, when a full system would cost about $2000 from the same supplier.

At the end of the day, it looks like we won’t do anything about our hot water system for now. It seems a waste to completely replace it when there’s nothing physically wrong with the existing system. Although it uses a lot of electricity, it’s off-peak so the running cost is pretty low (perhaps $200/year). I think it’ll be better to wait until it fails to replace it – and now we’ve done the research, we have a pretty good idea about what type of solar system we’d get.

The suppliers that were present claimed that a hot water system like ours has an expected lifespan of 7-10 years. That seems very pessimistic to me. Ours is 10 years old and still in perfect condition – and the system it replaced was 25 years old! I figure we’ve got at least 5 or 10 years’ service left before it dies.

For now, that $2000 could be better used on something else.