hotovoltaic panels are generally installed by application of empirical rules based on the principal goal of avoiding shadows during most of the periods of high solar irradiation and secondly of limiting the loss of diffuse solar irradiation. An installation on a horizontal surface results in largely spaced rows of panels with a relatively low tilt angle. The addition of inter-row reflectors permits to transmit more direct and diffuse flux to cells while resulting in a lower inter-row spacing and a higher tilt angle. The PV production process is a result of a combination of many physical processes which must be coupled in a model to accurately forecast the production of a given system in a given area. The “Aleph” project aims to define clear rules for optimal settings of systems of PV rows with fixed inter-rows reflectors in a given location and under a given climate. Two PV technologies are considered: amorphous silicon (a-Si) and polycrystalline silicon (p-Si). Optimization could result in maximizing the yearly or winter production, or the produced energy per unit of PV or roof surface. Any other techno-economic factor can be optimized: financial payback, energy payback… This work combines experiments on panel behaviour in an outdoor environment on SIRTA meteorology platform and an “infinite row model” (IRM) based on Cartesian optics and analytical solutions. It includes visible and near infrared radiations, angle-dependant reflection, absorption and transmission, calculation of the effective irradiation and temperature dependant cell efficiency. The experiment shows 5 to 32% gain in daily electricity production.