Disclosed herein is add-on electronic circuit structures and methods for providing protection against reverse-electrical-current failures and for enabling comprehensive electrical (current-voltage sweep) and electro-optical (electroluminescence or EL using reserve current flow) testing of solar photovoltaic cells and modules having at least one multi-modal maximum-power-point tracking (MPPT) power optimizer integrated circuit chip to increase electrical energy generation yield of the modules. Such multi-modal MPPT power optimizer chips are used for distributed solar electric power generation enhancement in solar photovoltaic cells, modules, and systems under realistic operating conditions with non-ideal manufacturing and environmental variations (e.g., variable and/or non-uniform sunlight or daylight, mismatched cells, etc.).