<p><span style="font-family:Arial,Helvetica,sans-serif">The shape and geometry of a solar collector is an important factor in solar-to-thermal energy conversion. In this paper, a new stationary solar collector called helical solar collector was designed and investigated. The performance of this collector was experimentally studied using ASHRAE standard. Experiments were performed with water as a working fluid in the outdoor condition of Ahwaz, a city in the south of Iran. The findings indicate that the average of its thermal efficiency is about 53%, and that it can be used as an efficient new water heater. The experiments show that the efficiency of the helical solar water heater increases through adding the mass flow rate.</span></p>