The sentence is correct and usable in written English.
You can use the sentence to indicate that the demand for something is strong or substantial. For example, "The demand for electric cars is solid."
Demand is solid, he says, but profit projections are hard.
"I think there is no change in the trend that production is expected to stay on a steady recovery as June trade data was good, benefits from the yen's weakness are appearing, and domestic demand is solid," said Yoshiki Shinke, chief economist at Dai-Ichi Life Research Institute. Dai-Ichi Life Research Institute
However, CEO Michael Dell said that enterprise demand is solid.
Domestic demand was solid, but foreign trade had a negative impact on growth with exports falling faster than imports.
"The Treasury managed to get all its debt out the door this morning, demand was solid, if unspectacular, and yields continued to fall," Mr. Spiro said.
Demand is also solid in Australia.
Demand worldwide for copper is solid.
Meanwhile, there is solid demand from developing economies, which the World Bank estimates have contributed as much as 70 percent of the growth in global imports in the last five years.
Economic growth is solid and demand is holding up (though consumer confidence slipped for the second time in a row this month and higher interest rates should eventually take their toll).
What they lack is solid aggregate demand of the kind that well-targeted government spending programs can enhance, and of the kind that cut-backs in public spending (laying off teachers and the like) can only weaken.
Mark is solid, really solid.
