The two types of solar hot water panels
There are two main types of solar hot water panels for sale:
- Panel Based Systems
- Heat Pump Systems
Panel Based Systems
Hot water solar panels systems use flat solar hot water panels that sit diagonally on your roof. These panels collect the heat directly from the sun’s rays and transfer it into your household’s water by being pumped through the panels. The water heats up as the sun’s heat is absorbed into it, which is then stored in an insulated tank.
So what happens when it’s not sunny outside?
Once the heated water that has been stored in the insulated tank has been used up, the system relies on a backup fuel source. This comes from either electricity or gas, depending on what system you’ve chosen.
The efficiency of your system will depend on where you live. For example, if you live somewhere like Darwin or Cairns, up to 100% of your hot water can come from your solar hot water panels. Whereas in a location like Hobart, about 50% of your water would generally be heated by your solar hot water panels.
Heat Pump Systems
Heat pump systems look a lot different to what you might consider on of the typical types of solar hot water systems, but they still do some amazing things using the natural resources of the sun.
Heat pumps work best in warm and humid environments, so if you live in a cold, dry climate where the temperature regularly goes below zero, a heat pump system may not be the most efficient for you. Air-sourced heat pumps work in a very similar way to that of your fridge or air conditioner, but instead of taking the heat out of an area, the heat pump works by absorbing heat from the air and transferring it to the water. Heat pump systems do rely on electricity to transfer the heat into the water, but they use almost 75% less energy than the traditional electrical hot water system.
Electric heat pumps are the way to go if you live in a warm and humid environment. Even when the outside temperature lowers, the system can rely on an electric booster to ensure that you have hot water year round. They also have plenty of benefits that may be useful regarding your own circumstances:
- If you have limited space or access
- Where solar energy is not applicable, for example lack of roof access, lack of sunlight, poor orientation or shade
- Natural gas is not available
Solar hot water panels: flat-plate or evacuated tubes?
There are two options when it comes to choosing between the types of solar hot water systems. These are flat plate collectors and evacuated tubes. Let us show you which of the solar hot water panels for sale on the market are the best…
Flat plate collectors are most commonly used for domestic solar hot water heating. They are shallow rectangular boxes made from aluminium with a glass lid topping it. Their dimensions are generally between 1 and 1.15 wide by 2 and 2.5 metres long.
The aluminium box holds the copper pipes that carry the water through the collector to absorb the sun’s heat, and is topped by a glass lid. The copper pipes are usually made in the style of a grate, as shown below.
The pipes as they are inside the box will still heat the water, but their efficiency is lowered. To maximise the panels’ efficiency, the surface area of the panel needs to be maximized so that it can get the best amount of benefit from the sun’s rays. To achieve this, horizontal fins are welded in between the pies, with insulation placed at the bottom of the aluminium box. These factors help to maximize the heat absorbed into the panel, therefore getting the highest possible amount of heat into the panel itself, which directly affects how much hot water is collected.
This is what a finished panel looks like beneath the glass panel.
And with the glass panel added.
As you can see, the flat plate collector is a relatively simple device, which means that they’re cheaper to manufacture and very reliable. Another great feature of the flat plate panel is that they are very resilient, meaning that they are well suited to the harsh Australian environment.
Evacuated Glass Tube Collector
The evacuated glass tube collector is the best option for solar hot water systems in colder parts of Australia. The more complex operating system and design varies widely depending on its use. However, its operating system means that it can appeal to the need for solar powered hot water in areas that have less direct contact with the sun.
Evacuated tube glass collectors operate in a way similar to a greenhouse. The tube glass collectors draw heat from the sun through a number of annealed tubes that have individual heat-absorbing plates built within them. The tubes work like small greenhouses as they trap the heat from the sun inside the glass tubes, which are then used to heat water either directly or through a heat transfer system.
The name of the evacuated glass tubes comes from the vacuum that is created between the inner and outer tubes during the manufacturing process. The insulation provided by the vacuum makes the glass tubes an extremely efficient solar heater. The roundness of the tubes means that it can collect heat from the sun throughout the day, which differs from the flat plate system as it can capture the sun’s rays only in direct light. This means that the evacuated glass tubes are more efficient as they can absorb more sunlight for a longer time.
The evacuated tube glass collector system is a lot more complex and, as such, more expensive to manufacture than the flat plate collectors. As they are also made predominantly with glass, they can also be quite fragile. Despite these drawbacks however, the evacuated glass tube collector is a very beneficial system. The improved performance of their tubes is more noticeable during the colder months and in colder climates when more water is heated through the collected solar hot water panels rather than from the booster, showing it to be a much more efficient alternative.
So, although the evacuated tube collector is more costly initially, it delivers great results for colder climates making it a brilliant option to save you money in the long run, while also being environmentally friendly.
What’s the best option for you?
It really depends on the climate where you live. Both the flat plate collectors and the evacuated glass tube collectors have their own individual benefits that work better for different climates. This diagram shows the percentage of heat that is collected from flat plate collector systems in each state.
The flat plate collector system works better in states where the amount of sunlight during the day is a lot higher. So for Queensland, the Northern Territory, and Western Australia, the flat plate systems are ideal. However, in places with a colder climate where there might not be as much exposure to sunlight, the evacuation tubes are the more efficient option.