How big does a solar panel need to be to power a 1W light bulb? It is difficult to answer this question. First, you haven't specified how long the lighting will last. Second, you haven't stated how many rainy days it will take. to ensure normal lighting.
I calculate based on 6 hours of lighting per day, 3 to 4 days of rain can ensure normal lighting. The battery must be 12 V/2 Ah.
The solar panel must be 18 V/138 mA (2.5 W).
It should be no problem to achieve the shape you want. You must make this request to the solar panel manufacturer. The quantity is basically acceptable. If the quantity is not right, you can also request a sample!