The phrase "a much more solid" is correct and usable in written English.
It can be used when comparing the strength or reliability of two or more things, emphasizing a significant improvement or difference.
Example: "After the revisions, the proposal is now a much more solid plan for our project."
Alternatives: "a significantly stronger" or "a far more robust".
Manhattan schist seems like a much more solid foundation on which to build your earthquake preparedness.
A much more solid deer is walking along the high ridge-line that borders this property.
This experience will help you get a much more solid insight into everyday practice of environmental management.
All one can do is hope that the city will be rebuilt with a much more solid social compact, as well as better hurricane protection.
Hull had already missed with two rushed drop-goal attempts but Saints provided a much more solid platform for Sculthorpe and their multi-skilled captain did the rest.
She has put it on a much more solid financial footing and added sidebars that include an avant-garde arm, "The Cutting Edge at the Cutting Room," on Friday evening, and early-evening panel discussions at 54 Below on Saturday.
While it's nowhere near as light as a Kindle, it feels much more solid and because it's significantly larger, is easier to hold with two hands.
For one thing, the floors in a laboratory need to be much more solid.
"As an away performance it was much more solid and structured than we've been, but detail is the difference between winning and losing.
Seeing the war as a rebellion fomented by slaveowners created a common antislavery ground among a wide swath of white Northerners that was much more solid than abolitionism.
"Germany, France and Italy want to be the motor of a Europe that is much more integrated, much more solid and with regulatory mechanisms that are virtuous, that don't allow a cheater, so that there is no one who can exempt themselves from the rules that are set".
