The efficiency of photovoltaic systems

Abstract

At this work the principle aim is to create new low cost hardware test circuitry that can emulate the behavior of solar cells under different insolation and temperature conditions. Another goal is to propose a new MPPT algorithm that could accurate and reliable estimate the maximum power operating point.
The transcendental equation describing a solar cell IV characteristic contains current on both sides in a function of the form I = f (V, I). In this work, a current-independent voltage expression is derived for the maximum power point as a function of a new variable which is mathematically well defined. Validation is performed on four different photovoltaic modules. The best case scenario has shown a divergence in Pmpp of 0.08% while the worst 0.84%. The new method is examined for sensitivity, up to %5± on values of five fitting parameters (Rs, Rsh, n, Io, Iph), with Iph to have the higher impact effect (up to 5% error).
Two topologies, of VBE multiplier, have been proposed that can reliably emulate solar cell operation. Analysis shows that both circuits have the potential to deliver good quality characteristic IV curves with small RMSE (10-3). The second improved VBE multiplier has the ability to operate over wider range of illumination and temperature conditions. Through this model it was possible to build a low cost (£230) fully functional prototype digital controlled emulator solar system “DiceSol”.
A MPPT device has implemented based on a powerful mathematical modeling tool. The proposed method “Goose Waddle (GW)” was employed on a boost DC/DC converter configuration. Excellent static and dynamic performances were exhibited. At all cases considered convergence is higher than 98.53% while convergence time is on average 220 msec.

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