Solar Hot Water System

Use the sun, not electricity, for free hot water

There are several makes and models of solar hot water systems available on the market, but the most popular design here in Australia would be this one from SolarHart. I snapped this picture of it on top of a house near Ryde Swimming Pool, Sydney, NSW.

The SolarHart consists of two hot water panels connected side by side. They are like a sealed metal-backed glass frame containing sheets of blackened copper which absorbs the sun's rays and transfer that heat to the surrounding water.

Cold water is heavier that hot water, so it sinks to the bottom of the solar panels naturally by gravity, and then rises up by convection and fills up the water storage tank as it gets hot.

The cold water enters the panels at the bottom left, and exits as very hot water at the top right from where it flows into the tank. No electric pump is needed here, although some other solar hot water systems may have their water tank concealed under the roof. That makes them nice and low-profile. However the ones I have seen used an electric pump to move the hot water. For me, that's a mark against those systems because the pump is another part device which can break down or just wear out.

In full sunlight the water gets very hot indeed, and there is no need for electricity. However, an electric booster element is included in this model so you can still have hot water on cloudy or rainy days.

If it only rains or clouds over for one day, you will probably have enough hot water not to need the electricity at all. But in winter months the booster will be used more often. I installed one of these myself on a property that was off the mains grid, and it has functioned perfectly for years without electricity. But that was in country Queensland, a pretty warm area.

The solar panels need to be placed on the sunny-side roof of your home. Here in the southern hemisphere, that means the north side, so the panel gets the noon day sun. In the northern hemisphere — such as the USA and north America, and for Europe, you would want your solar panels facing the south. But in cases where this is not possible, having the panel face west, for the late afternoon sun, is the next best thing.

But have you thought about a solar hot-water system to heat a swimming pool? That would have to be a lot bigger...