The phrase "a solid increase in" is correct and usable in written English.
It can be used when discussing growth or improvement in a specific area, such as sales, performance, or metrics.
Example: "The company reported a solid increase in quarterly revenue, indicating strong market demand."
Alternatives: "a significant rise in" or "a substantial growth in".
Britain's factories bounced back from a dismal 2015 to post a solid increase in output in the first month of the new year, official figures have shown.
The New York Times Company posted a solid increase in third-quarter profit yesterday on growth in advertising and subscription revenue, despite the sluggish economy.
The firm experienced a solid increase in revenue from various segments in this department, including debt and equity underwriting, investment banking, and currency and commodities trading.
ATLANTA — Delta Air Lines, the nation's No. 3 carrier, said Wednesday that it was hampered by high fuel prices in the fourth quarter but was able to narrow its loss because of a solid increase in sales.
Banco Santander — the biggest Spanish bank and one of the largest in Europe — reported a solid increase in year-end profit on Thursday, helped by growth in Brazil and Britain and a turnaround at its United States unit, Sovereign.
Coca-Cola, the world's largest beverage maker, reported an 11% drop in first-quarter profit despite a solid increase in sales.
Spiegel explained that improvements to Snapchat's Android app performance boosted retention by nearly 20percentt compared to a year ago, showing a solid increase after the company neglected Android in its first few years.
While populations appear to be down this year, Dr. Graham, of South Alabama, sees a "statistically solid increase" in the region over the longer term.
The stronger demand helped manufacturers pass on some of their rising costs with "a further solid increase in average selling prices", according to the report.
Again, that's a solid increase from the 21 IPOs in 2016 that raised a paltry $2.9 billion.
The solid increase in retail sales showed that Americans kept spending despite a payroll tax increase that has lowered take-home pay this year for most workers.
