A solar collector, also referred to as solar thermal collector, absorbs sunlight and converts it into usable heat. The energy is transferred to the storage water tank, making hot water available for domestic purposes. We have two main types of collectors to choose from; flat plate or evacuated tube. However, users have been engaging into constant debate based on which works best.

Flat Plate v’s Evacuated Tube Collectors; Which To Choose?


Flat plate collectors produce maximum heat at about 140F, while evacuated tube collectors can perform up to 200F. However, evacuated tubes work better in colder or cloudier weathers since they can retain high amount of heat due to their evacuated glass tube. This makes them suitable for freezing conditions. Flat plates on the other hand, performs better in areas experiencing heavy snowfall because they can melt the snow faster by reflecting heat off the ice. If the weather is too cold throughout, flat plates will not produce hot water.


You can choose either flat plate or evacuated tube, depending on the climatic condition of your area. Evacuated tubes are a bit more efficient than flat plates because they can be installed at a wider angle facing the sun, with their tubes separated to allow the ice to slide off more easily. However, flat plates will work efficiently in sunny climates.

solar plate


Whichever types you choose, flat plate or evacuated tube, both must be mounted on a surface where they can absorb huge amount of sunlight. Evacuated tubes are more lightweight and easy to install, and their round shaped tubes allows them to absorb more sunlight. Flat plates are more sensitive to sunlight, and should be positioned at elevated angles to enhance their ability to absorb more heat. Therefore, a reliable dealer can give advice on which technology to adopt according to your needs.


Design is a key factor to consider when choosing either flat plate or evacuated tube collectors. With the unsealed enclosure of the flat plates, they are more prone to corrosion over time due to condensation. Although condensation doesn’t affect the overall functionality, you will be required to replace the entire panel when serious corrosion occurs. Evacuated tubes have evacuated glass tubes that help in retaining heat, though they cannot perform without the vacuum. Every tube’s vacuum status can be easily monitored, and if the vacuum is lost at one point in time, it is easy to replace the tube.

solar collector


Cost is one of the main limiting factors when it comes to choosing either flat plate or evacuated tube collectors. Since it depends on individual’s needs and budget, consulting a local dealer can be a better option. However, you need to compare price based on cost per BTU capacity, as well as annual performance. Location is also very important, bearing in mind that these two collectors perform best in different climatic conditions. In cold conditions, 2 to 3 flat panels may be required to give out same heat as a single evacuated tube collector. Since evacuated tubes are more expensive than flat plates, flat panels can be your choice for sunny areas.