We got a Chromagen system – they’ve been around for a long time, and seem pretty well-made and reliable. We bought through Earth Utility, one of the sponsors of the Sustainable Illawarra program we’re participating in. Note that we didn’t get any special deals or anything; we were just another regular customer to them. The service and price were both excellent.
WARNING: Earth Utility appears to be in trouble (updated 28-04-2010).
There are two general options with solar hot water: flat panels and evacuated tubes. We went for flat-panel, since evacuated tube was more expensive and we have good direct sun all day. The tubes are apparently more efficient, with a profile of good heat production throughout the day, which makes them great for areas with less sun than us (Tasmania, Snowy Mountains, etc).
We chose a system with a 300L tank, since our 300L electric off-peak tank had never run out on us – that seems to be the right size for our family. Also, we had the old tank turned down to about 60 degrees (minimum temperature), whereas solar systems heat the water to 70-90 degrees, so we’re actually getting more hot water than before anyway (or the same amount of hotter water, which goes further when mixed with cold for showers).
Since the old tank was off-peak 1 (night-only off peak, the cheapest rate), we kept that as the boost for the solar hot water system. The boost for the solar system uses 3 kWh/day, whereas we were using 8-9 kWh/day for electric off-peak, so it’s quite a good energy saving. I’ve now turned the boost off completely and we’re just using solar for heating, so our energy consumption is now zero. Most people around here suggest only turning the boost on during winter or if we get a few days in a row of heavy cloud. The extra capacity should carry us through a day or two of cloudy weather.
I was originally wanting to get a thermosiphon system (tank on the roof at the top of the panels) because that’s the most efficient configuration (no pump is required). It turned out that installation would be very expensive for us, though, since our driveway is too steep for a normal crane to lift the tank onto the roof. So we changed to a split system with the water tank in the back of the garage where the old one was. It’ll probably last longer, being inside instead of on the roof.
Also, in NSW you have to install a tempering valve (temperature regulator) to ensure the water going to bathrooms is kept to no more than 50 degrees. It’s supposed to stop children and other unsuspecting people from burning themselves, since solar hot water can get as hot as 90 degrees. Some people run additional pipes to get the untempered hot water to the kitchen and laundry, but we just got the valve installed straight on the outlet of the hot water system. Hot water at 50 degrees is fine in the kitchen or laundry, and I’d rather keep everything safe for the kids.
We were really happy with the work done by the Earth Utility installers. They routed the pipes really neatly around the hot water unit and up the outside wall, and made sure everything was insulated properly (important for both safety and efficiency). They needed to get electricity to the pump (used to move the water up to the roof and back), so they installed a new double powerpoint near the tank at no extra cost. We didn’t ask for that, they just decided it would be a good idea. How often does a tradesman do that these days?! It’ll come in really handy, since there wasn’t power in that corner of the garage previously.
Overall, we’re really pleased with our new solar hot water system. Purchase and installation were quick and easy, it looks great, and it’s working perfectly. We wouldn’t even notice it was there except for the reduced electricity bills!