Last week I wrote about a couple of revolutionary projects that might lead us to rethink the way we design and build shelters. Meanwhile, during this year of monitoring and evaluating the performance of the Greeny Flat we are doing a lot of thinking about what we could have done better in the design and construction of this little house. I’m pleased to report that there is very little that we would change if we were starting again but there is one major thing that we would do differently.
No Solar Hot Water
This might come as a surprise to some readers but we would very likely not install a solar hot water (SHW) system, certainly not a split system like we currently have, and definitely not anything made by Apricus.
What’s wrong with a Solar Hot Water System?
The main problem with the particular SHW system that we purchased is that it was extremely expensive. After much deliberation we selected a ‘top-of-the-line’ split system with an Apricus APKR-20 Evacuated Tube collector, an Everlast Series 2000, 160ltr storage tank, a DeltaSol BS/4 Controller and a price tag of about $6250. There a many cheaper systems on the market and, in future, I might consider using a less expensive option, at least to pre-heat our water. But, if you’ve been following the results of the Greeny Flat experiment , you’ll know that we are making way more energy than we are using. What we could really use is a way to store some of that energy during the day for use at night. The simplest way to do that would be to heat water. If we didn’t have this super-fancy and expensive solar water heater, we could simply use our excess electricity to heat a tank full of water during the day for use at night. In effect this would still be a solar water heater we would just be converting the sunlight to electricity first, then the electricity to hot water. This would be somewhat less efficient but much simpler and less expensive and it would help us to reduce the amount of electricity that we export to the grid. We only get paid 8c/kWh for what we export and we pay 22c/kWh for what we import so it’s better for us to make use of the electricity directly rather than export it. In short, the SHW system we have is way more complicated and expensive than it needs to be.
What’s wrong with a split Solar Hot Water System?
There are a lot of different types of SHW systems which are described in detail in the Wikipedia article on solar water heaters. In Australia there are two main types available: ones that have the tank attached to the top of the collector panel (called ‘close-coupled’ systems); and ones that have the tank separate from the collector panel (called ‘split’ systems). As you can see from the images below, it’s easy to tell the difference when you see a SHW system on a roof because the close-coupled system has a big tank on top and the split system doesn’t.
The other thing you can glean from these images is that the split system requires a complex arrangement of pumps, controllers, valves and piping to make it all work whereas the close-coupled system is much simpler and works by the natural tendency of hot water to rise (called the thermosyphon effect). So, in future projects I might consider using a close-coupled system to pre-heat the water but I’d be very reluctant to use a split system again.
What’s wrong with Apricus?
Apricus has a very good reputation as the Australian leader in SHW technology. Their website makes them sound like a wonderful company to deal with. Their ‘Core Values’ are listed as:
- Building strong relationships with customers.
- Providing the highest quality product.
- Providing the best possible support.
- Having the “good bloke” factor; Going above and beyond for our customers.
Sounds good doesn’t it? The trouble is that, at least in our experience, they haven’t lived up to any of these promises. In fact:
- There are some serious shortcomings in the design of the product, particularly the lack of a user interface for monitoring and control of the system and the poor design of the smaller storage tank which we were forced to use due to the low height of the available space above our bathroom.
- We have made many attempts to raise these issues with Apricus and have met with a very poor response.
- Their customer service is almost non-existent.
- Most of the ‘good blokes’ at Apricus that I have tried to contact haven’t even bothered to reply. The ones that have responded have been very slow and their responses have generally been unsatisfactory.
In short, I would never use an Apricus product again.
So what would we do next time?
Next time I will most likely do the simplest thing possible that would still allow us to use the sun to heat water. That probably means that I would simply have a good, old-fashioned, electric tank water heater with an element. This is simple, tried and trusted technology that every plumber understands, can install and repair. It is also silent and has no moving parts so requires minimal maintenance. I would set this up on a timer to run between 10am and 2pm every day which is the period of maximum production from our solar power system. Since we seldom use any other electricity during the day this would allow us to store a lot of our excess power in the form of hot water. To summarise, such a system would be:
- Inexpensive to install
- Inexpensive to operate
- Easy to maintain
- Easy to repair
- Easy to understand
If I had a good place for it with easy access I might consider using an inexpensive, close-coupled SHW system with a flat plate collector to pre-heat the water on sunny days. Of course on cloudy days we would be using grid power to heat the water but that is true now with the expensive and complex solar hot water system that we currently have.
And so we live and learn…