Photovoltaics in the shade: one bypass diode per solar cell revisited

Deployment of residential photovoltaic solar energy systems is strongly increasing, which gives rise to problems such as partial shading and pollution, omnipresent in the built environment. Conventional modules are sensitive to the current mismatches introduced by shadows because of their series architecture of electrical interconnections. This paper presents simulations and experiments showing that a new generation of bypass diodes (BPDs) can be used, up to 1 BPD per cell, to improve the shading tolerance of conventional crystalline modules. We have used cardboard of 0% transmission, and a wire mesh (net) of 38% transmission. The more BPDs are used, the higher the maximum power under shading conditions. Using 20 smart BPDs, or 1 BPD per three cells, leads to an improvement of a factor 3 in power output; for our netting experiments, a factor 1.5 is found. Both performance enhancement and lower diode temperatures lead to increased shade resilience and reliability.