Photovoltaic installations typically use fixed-mount photovoltaics (PV) panels with a constant orientation throughout the year. However, this does not maximize the energy output since the irradiance received by the panels depends on the sun position and the weather. This paper presents a novel approach to maximize the energy produced by fixed-mount PV panels for short-term and for permanent PV installations. For permanent installations, we considered a multiple-tilt scenario where the panel orientation is modified throughout the year. We developed a bi-layer algorithm to optimize the angles and timing of adjustments. Our method has been implemented in an open-source software, allowing optimal orientations and dates to be calculated for any installation. The optimal dates and the optimal angles have been successfully calculated for PV panels located at Reykjavik (Iceland), Sherbrooke (Canada), Quito (Ecuador), and Brasília (Brazil). We found that two reorientations per year were the most suitable option for all locations, resulting in a 3 % to 4.8 % gain in annual energy production compared to no reorientation. For short-term installations, using optimal orientation can improve energy production, with for instance 13 % improvement for a monthly installation in Brasilia.