Noisy contactor
Put piece of styrafoam between box and wall
Use plastic box instead of metal
Insert plumbing washers between contactor and box
Do not attach box directly to wood or metal structure
Connect with flexible and plastic conduit instead of rigid steel
Other options
Latching contactors are generally used for commercial lighting, because of noise, cost efficiency and durability.
To turn on, they receive a short input or signal from control system (usually some kind of PLC or sometimes a timer that is rated for pulse). To turn off they receive another short input.

Solid state relay will work . It runs hot, and sometimes requires a heat sink... meaning it consumes more power than your regular contactor. Probably not the best choice because when it fails, it fails in ON position and not off position.
SSR is all-electronic and has no mechaical switch or internal connection that seperates two points.
SSR is usually for electronic circuits utilizing DC where the issue of arc extinction is greater problem than heat loss from SSR..... that gets into difference between AC and DC electricity.

The contactor is efficient and durable. It consumes 7 watts, with 30 watt inrush ... so it is efficient, and rated for millions of operations ...,. commonly found in air HVAC and industrial applications .... available at electric or HVAC supply houses, should sell for 9-15$ for 20-30 amp, and more for higher amp rating... up to $100s for 90 amp etc.
The contactor is noisy in some installations depending on what they're attached to ... wood surfaces are the worst, and concrete wall in back of garage the best. Plastic enclosure is better than metal enclosure.
I've been meaning to add this information to my website... and now your email gave me opportunity to review the issue.