In terms of thermal efficiency, HKWELL hybrid panels are different from conventional solar thermal panels.

 The main difference lies in the front face of the panels.

A solely thermal solar panel consists of a double-glazed front panel, which makes it possible to create a greenhouse effect, while the HKWELL panel is covered with photovoltaic cells, therefore with single glazing.

The performance of thermal and hybrid solar panels is described by the following coefficients:

• a0: The optical yield, which represents the percentage of incident solar radiation that will actually be absorbed by the solar collector. It characterizes the transparence and absorptive capacity of the collector. The close this value is to 1, the better the quality of the collector in this respect.

• a1 (measured in W/K⋅m²): The first-order coefficient, representing the constant-percentage losses, due to conduction and convection essentially. The smaller this number is, the lower these losses are and the better the collector is in this respect.

• a2 (measured in W/K²⋅m²): The second-order coefficient, which describes those losses which increase as a function of temperature, due to infrared radiation essentially. Again, the smaller this number is, the lower these losses are and the better the collector is in this respect.

 The following table provides a comparison of these coefficients in a conventional solar thermal panel and a HKWELL SPRING panel:

*Sample coefficients for a commercially available solar thermal panel

We find that hybrid solar panels do not have the same performance as solar thermal panels.

This is normal and in fact intentional: the HKWELL  panel was designed not to rise to very high temperatures so as not to negatively impact photovoltaic production. At the same time, this eliminates the risk of thermal overheating.

This way the stagnation temperature of a HKWELL panel never exceeds 80°C, while a conventional solar thermal panel can reach temperatures well above 100°C and consequently bring the heat transfer fluid to a boil.

By its very design, a HKWELL SPRING panel is therefore unable to reach hot water temperatures as high as a conventional thermal panel.

The normal operating temperatures of HKWELL hybrid SPRING panels are approximately:

• Summer: 55-60°C

• Spring/Autumn: 40-45°C

• Winter: 30-35°C

Thus it is necessary to plan for a larger hybrid panel area to achieve a coverage of domestic hot water needs similar to that of a conventional solar thermal installation, around 1.5-2 times more area depending on the application.

However, a HKWELL installation, compared to side by side photovoltaic (PV) and thermal (TH) modules rated at the same power, will take up 30% less roof space.

HKWELL presents multiple advantages including rooftop space, efficiency, design and cost! First, HKWELL panels, due to their innovative and patented hybrid technology, perform much better than standard photovoltaic panels. Photovoltaic panels become less efficient as outdoor temperature rises.  

Due to the HKWELL panel’s heat exchanger, water circulation on the backside of the panel cools the PV frontside of the panel, allowing to increase the PV efficiency of the panel, AND generate hot water at the same time!  With HKWELL, 1+1=3 and you save 30% of rooftop space for the same installed power output as for two separate PV and thermal installations.   Moreover, aesthetically, a HKWELL installation is composed of one type of black-black panel, and thus is more visually harmonious than two separate PV and thermal installations side-by-side.  

Note that a HKWELL panel has the same visual appearance as a PV panel, so you can decide to complete a HKWELL installation with additional PV panels without changing the aesthetic look of your installation. Finally, the labor costs of a HKWELL installation will be lower than two separate installations because the installation is less complex and requires less maintenance.

 Where two PV and thermal side-by-side installations will require 2 different types of mounting, a HKWELL hybrid installation will only require labor for 1 type of mounting system. These are the principal reasons why you choose HKWELL over two separate PV and thermal installations!