Accurate & highly performant


Accurate & highly performant

As mentioned in the short definition the solar tracker, whose electronic board is placed in the basement of the structure, is highly accurate since it is using an innovative algorithm that is based on geopositioning. This means the sun apparent coordinates are calculated from the geographical coordinates provided by an electronic GNSS module and therefore the system works with full accuracy everywhere in the world with no configuration tasks required from the user like in other tracking systems. This advantage is particularly necessary in a portable system like the one presented.

Strictly speaking the improvement in performance from a tracking system depends on the latitude and also the altitude. The theoretical calculation requires the solution of the apparent solar astronomical equations and the application of the air mass factor that refers to the atmospheric thickness sun radiation crosses for each sun apparent position.

The resulting radiation power per unit area can be calculated for different latitudes (and altitudes) and compared with the one crossing a fixed unit area in its optimal orientation. In a previous phase of the project this calculation was carried out applying Cooper's method for the calculation of sun declination and using a spherical atmosphere approximation. The resulting annual energy generation that is obtained from the integration of these powers along the year gives an accurate approximation of the potential energy increase when using a tracking system. This theoretical calculation was also experimentally confirmed in good approximation and as an indicative basis it reaches 49.55% in Madrid (Lat 40.5ºN & Alt 690m) and varies from 44.5% in Dakar, Senegal (20ºN) and 73,91% in Narvik, Norway (70ºN).

Since the panels weight and size in each structure is limited there's crucial interest in integrating the highest efficient solar cells available in the market that can be assembled in semiflexible panels. Traditional solar cells are typically reaching efficiencies around 15%. The current Sunpower cells used in the demonstrator are reaching efficiencies around 20%. The identified companies with highest efficiency cells are being contacted to check out the possiblility of building semiflexible panels using their cells.

As said in the short description the tracking system improves significantly the generation pattern of panels making it much flatter in comparison with those using fixed structures. The need of storage capacity is this way significantly reduced and the energy management is easier and more efficient. The following figure shows this flatness difference and how in line is with the experimental data recorded in recent field tests.