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Flat Plate Solar Collector

What is a Flat Plate Solar Collector

Flat plate solar collector is a special heat exchanger that transform the radiant solar energy from the sun into heat energy. It uses the blue titanium selective absorber sheet makes absorbing volume up to 95% of available sunlight converting into usable heat for hot water production. Comparing to the vacuum tube or any other solar water heating systems,it tends to be most effective collector for residential or commercial hot water heating projects due to their simple design, low cost, and relatively easier installation.

Components of a typical flat plate solar collector:

Transparent Cover

Super white 3.2mm thickness toughened glass makes over 92% solar energy can go through.


It is made of 0.4mm thickness thin aluminum sheet that is coated with a highly selective blue titanium material features extremely efficient at absorbing sunlight and transforming it into usable heat. Furthermore the aluminum sheet is laser welded to the cooper riser tubes.

Insulation sheathing

The insulation sheathing do a great job on preventing the heat loss from the sides and back of collector, it is made of light weight fiber glass in 35-50mm thickness and 50-60Kg/m³.

Back Sheet

The 0.4-0.8mm thickness aluminum or galvanized back sheet adds to the rigidity of the collector.

Riser Header Pipe

TP2 Cooper laser welding header and riser tubes form a harp shaped heat exchanger together so that the solar heat transfer fluid circulates in heat exchanger.

Aluminum Frame

The 1.5mm thickness 6063-T5 oxidation treatment aluminum frame is widely used for anti-corrosion, anti-rusting, etc.

EPDM Sealing

Special integral EPDM material can avoid leakage perfectly, otherwise, its service life is over 25 years.

components of a typical flat plate solar collector

Advantages of Flat Plate Solar Collector and Our Features

Sinoyin solar is one of professional manufacturer and supplier of high end flat plate collector in China in 2008, we are aimed to provide the hot water solution for residential commercial use, in hospitals, factories, hotels etc. Due to the significant features of our collector of high efficiency, easy installation, clear water assurance, also our products had successfully get the certification of Solar Key-Mark, SRCC, so it had gradually became the domain product around the world solar hot water energy product, and it is widely used in domestic hot water, swimming pool heating, industrial water heating, architecture heating etc.

High Solar Thermal Efficiency

Our flat plate solar collector is combined with several copper tubes, and there are gaps between each tube. When the sunshine heats the tube, flat collector with its flat surface can absorb the whole sunshine. Therefore, on the same area of the same sunshine conditions, the efficiency of flat collector is 6% higher than the vacuum tube,solar absorption rate up to 95%, and emissivity less than 5%.

Thermo stability Anti-Freezing

With heat-resisting material, our collector can work even in very hot environment, which temperature can be as high as 190°. Besides, our products have got the certificates of the Solar Key-Mark SRCC.
The anti-freezing function of the flat collector is important in cold regions. Normally it has 2 main anti-freezing technologies as follows:
1) Emptying antifreeze technology
It is suitable for the flat plate solar collector system area<100m2. The hot water tank is lower than system pipeline collector when the circulation pump stops working. The water in the collector and pipeline can be automatic to go back to the hot water tank for keeping the collector pipeline empty, so that it can do a help on anti-freezing.
2) Secondary heat transfer system of the anti-freezing liquid Special antifreeze liquid is an anti-freezing heat conduction liquid that combined with the antiseptic and Scale inhibition. It has good performance of heat conduction and can works well under the low temperature of -40°.

High Stability

Take some large site, hotels and swimming pools and factories for example. When using the solar water heater, normally it needs to combine multi plates together, thus the metal parts to joint different plates together are more stable than the vacuum tube.

Easy to install in anywhere

Unlike with the vacuum tube, all the tube need to assembled one byone,and it is easy to broken, also some small accessories is easy to lose.

Our flat plate collector is the whole integral part, only to need to use with quick slot to combine together, also it can be installed in flat or slope roof, no limitation of the places.

Flat Plate Collector Working Principle

Working Principle of Flat Plate Solar Collector

Converting solar energy into heat energy, then transferring the sunshine passed across the low iron safety transparent glass of the collector, which heats up, and gets a great amount of the radiation from the sun. Heat into working fluid, therefore the cold working fluid from the bottom of collector is gradually heated, so that temperature is rising. Finally the heated liquid is transferred back to the top of the collector of storage tank for using. Whole process is the useful energy collection. In the meantime, due to absorber plate temperature rise, only very little of the heat emitted by the absorber escapes the cover.

Flat Plate Collector Efficiency

In general judge a flat plate solar collector efficiency is based on third party test result, such as Australia Standards (AS/NZS 2712), SRCC OG100 and Solarkeymark from the following several parameters:

Power curve  

Based on Test method according to DIN EN 12975-2:2006 chapter 6.3, our FP-GV 2.15 collector had made the power of 1521.

Reduced efficiency Curve

Efficiency curve presents a visible result of the working efficiency of collector that is test by solar Key-Mark EN12975-2 2006 basis.

Efficiency curve over reduced temperature difference at 1000W/m² irradiation

Efficiency curve over reduced temperature difference at 800W/m² irradiation

However, it is lack of sufficient evidence to show that the real working efficiency of the collector, since it will differ from different conditions, like the environment temperature, the installation angle, the working conditions etc., therefore another three different surface areas that may be used to definethe size of a thermal solar collector: Gross, Aperture Absorber.

Gross Area

It is measured by the total width*height of the collector. This kind of measure including the outside frame, absorber coating part, it is considered to be the good way to judge the flat plate collector is worse to install on the roof.

Aperture Area

● Flat plate collector is depends on the area of the cover (glass) absorbers from the sunlight.
● Evacuated Tube Collectors: Calculated as the inner diameter of the clear glass tube. Aperture has been adopted by most countries and industry associations as the standard surface area to use when quoting efficiency values.

Absorb Area

Calculated as the exposed area of the solar absorb.

A flat plate collector may have a performance value of 79% based on aperture area, but because the gross area is almost the same as aperture, the gross value will only be slightly lower.

So above all, test result of efficiency is based on specific conditions, it will differ between different factors, the thin air condition, as a professional manufacturer of solar collector based in China since 2008, customized full-time solutions had provided to our customer from different regions, so that our  customer can make maximum utilization of the solar energy.

Solar Flat Plate Collector Design and Performance

Aluminum absorber plate’s anti-corrosion

The corrosion problem of aluminum absorber plate is a big concern that we focus on. This design is used with aluminum alloy as the basis material:
However the oxidation treatment is used on the surface of the aluminum, so it can prevent corrosion, but we developed the design for enhancing ability of anti-corrosion:
(1) Selection of anti-corrosion material:
Aluminum with magnesium is considered as the best anti-corrosion material.
(2) Excellent structure design:
Avoid crack, use sealing material on the part need to be gapped, better than laser welding.
(3) Anodic oxidation treatment:
Through the anodic oxidation treatment, can get 1000-3000 times better than autoxidation.
Through this methods, the absorber plate lifetime up to 10 yeas more.

Structure performance  

The flat plate collector is used with aluminum alloy frame, light weight(p=2.7g/m³),thermal conductivity(237W/m*℃),it is a whole part, no gap  between the copper tube and the absorber plate, so it is enjoys high heat transfer. It is easy to install maintained on the commercial solar water  systems.

Test result

The test is based on following conditions:
Absorber area: 1.8m2 Water tank: 90L Collector is stalled on the bracket
Tilt angle:30°natural circulation lowest temperature:3.7°Highest temperature: 8.7°minimum solar irradiation time 421W/m2, Maximum solar irradiation time 650W/m2, maxinum wind speed 4m/s, minimum wind speed 1.5m/s.

The test result is: water from 9℃ to 39.5℃, total power is 12445KJ/m2, so average efficiency on so bad environment condition up to 49.5%.

Above all, as for the improvement of the design of the collector from the absorber plate, aluminum frame, special insulation part etc. can get a better performance on the flat collector working efficiency.