Flat plate solar collector is one of the main solar collectors that has a simple structure, reliable operation, large heat preoccupation area, and low cost. Its drawback is the low heat transfer between the working air and the absorber plate. A solar air heater of V-shaped transverse finned absorber having new designed absorber plate of lateral gaps and central holes to enhance its performance is investigated experimentally at single-pass and double-pass airflow conditions. Moreover, the energy and exergy assessment of its performance was studied and compared with traditional longitudinal finned heater having the same fin surface area and construction except for the absorber plate design. The study is investigated at air mass flow rates of 0.025, 0.05, and 0.075 kg/s. Findings show that the new heater achieves maximum outlet temperature rising of 28.2 °C at 0.025 kg/s and double-pass flow. Moreover, it has an average daily energy efficiency of 88.5%, 81.88%, and 61.3% at mass flow rates of 0.075, 0.05, and 0.025 kg/s with increments of 9.4%, 13.3%, and 9.66%, respectively, compared to the longitudinal finned heater. Additionally, it achieves exergy efficiencies of 2.5%, 2.1%, and 1.7% at mass flow rates of 0.025, 0.05, and 0.075 kg/s with increments 18%, 25.7%, and 18.2%, respectively, relative to longitudinal finned heater. Furthermore, the new heater design possesses greater energy efficiency comparing to former studied SAH designs.