Films of poly (methyl methacrylate) PMMA and PMMA doped with zinc oxide nanoparticles (ZnONPs) with different amounts were created using the solution casting technique. Different amounts of zinc oxide ranging from (0.001-0.005) g in step 0.001g were investigated and added to a polymer of constant amount (0.5) g of PMMA in 15ml Tetrahydrofuran (THF). It is known that increasing the amount of ZnONPs in this technique contributes to the appearance of ZnONP peaks within the polymer. The differences in the XRD spectrum show that the nanomaterial changed the microstructure of the polymer. This was discovered using a nanoscale scanning electron microscope (SEM). SEM revealed that the PMMA polymer surface exhibit an amorphous nature with a smooth surface. Fourier Transform Infrared (FTIR) spectroscopy demonstrates that there was no chemical reaction between the PMMA polymer and ZnONPs. Spectrophotometric measurements of absorbance and transmittance in the wavelength range 200- 900 nm were used to evaluate the optical characteristics of all films. Increased amounts of ZnONPs improve the absorbance, absorption coefficient, and extinction coefficient of PMMA polymer. With increasing ZNO content, the variance in computed optical energy gap values has been interpreted, the optical energy gap dropped from 4.65 eV to 4.10 eV. The solar radiation intensity in Baghdad for the pure PMMA films and PMMA/ZnO nanocomposites was measured at a rate of 1 hour for seven days in beginning in early September 2021, from 6 A.M to 6 P.M (13 h). As can be observed, almost all films have the same ratio of intensity of transmitted radiation to intensity of sunlight for all hours and days.