TRAXLE Solar Pumping Systems

The TRAXLE solar pumping system with bifacilal panels may even double the amount of the water pumped used for example for drinking or for irrigation purposes.

There are only two slight differences as for the appearance of the TRAXLE bifacilal PV modules and of the standard unilateral PV modules:

• The rear laminate-coated sides of the bifacilal panels are with the application of a transparent layer instead of the white colour application in the other case
• Instead of the all-area contact a plated rack has been used as the contact on the rear electrode

As there is only a small or no difference as for the prices of the standard and of the bifacilal solar modules, it is most advantageous to use the bifacilal modules providing by 10-20% more energy in comparison with the standard unilateral modules of the same output performances and this mainly because of the three following reasons:

• An automatic mobile stand for solar collectors with the sun tracker and with the polar axis enables the light impact reflected by the Earth’s axis on the rear sides of the collectors. The usage of the radiation energy impinging on the rear sides of the photovoltaic panels enables an increase in the total amount of the energy generated by 5-10% with typical albedo 0.3 in comparison with the unilateral panels. In this case, the surface reflectivity in the installation place of the solar system shall be projected in the amount of the energy generated. The high reflectivity as for the visible radiation is for example with quartzy sand, lime-coated wall or snow, a worse reflectivity is for example with grass or soil and a very low reflectivity is for example the traprock.


• Usually for the whole night, the system with the Sun tracker is directed to the west in the position, where it finished its activity in the evening of the day before. Therefore, in the morning after the sunrise, the direct radiation shall impinge on the rear sides of the panels for some time until the retracking of the whole system to the east has been finished. Usage of this radiation with the bifacilal panels may increase the amount of the energy generated even by more 2-5% in accordance with the local conditions.


• The bifacilal photovoltaic solar panels are transparent for the infrared radiation. This causes a decrease in their temperatures in comparison with the unilateral panels by 5-12°C. This is in particular of advantage with the mobile solar systems with a moderate radiation (C = 1,6), where the photovoltaic panels are exposed to a higher radiation intensity. These systems shall be preferably mounted to higher stands so as to be well cooled down by the air circulation. The measurements show that the temperatures of the bifacilal photovoltaic (c-Si) panels placed on the automatically mobile stands are by 5-10°C lower than the temperatures with unilateral (c-Si) panels integrated into the rooftops. In case of mobile stands with rack radiation concentrators (C = 1.6) and with bifacilal panels the temperature differences in comparison with the unilateral panels integrated in the rooftops are lower by 4-5°C. The decrease in temperature with the bifacilal panels may increase the amount of the energy generated by 3-5% as the consequence of a higher efficiency of the photovoltaic energy transformation under lower temperatures of the solar panels. The reduced temperature also prolongs the service life of the solar photovoltaic panels, because the polymer degradation in their encapsulation caused by higher temperatures of the unilateral panels may be prevented in this way.

The combination of all three mentioned effects may thus increase the amount of the energy generated by 10-20% in comparison with the same photovoltaic system being with unilateral panels, a mobile stand and the rack radiation concentrator.

The total increase in the energy generated may thus actually be seen as to be of 100% in case of the system with bifacilal panels, a mobile stand and the rack radiation concentrator in comparison with the system being with the stationary stand, without the radiation concentrator and with unilateral panels. The increase in the amount of the pumped water makes up to 150%, because of the system moving above the threshold value for a longer period. The first value with the local maximum in the morning hours corresponds with the photovoltaic transformation of the direct solar radiation impinging on the rear side of the solar system before its morning retracking to the east.