'restricted solely' is correct and can be used in written English.
You can use it to mean that something is limited only to a certain extent or purpose. For example, "She was restricted solely to light duties due to her injury".
Muslim access to al-Aqsa has been restricted solely to men over 45 and women.
"It appears that this problem is restricted solely to the Epic Hotel and its residents," said Dr. Vincent Conte, an epidemiologist with the county health department.
In particular, we develop implicit time discretization methods for the advection diffusion equation where the time step is restricted solely by the advection part of the equation.
Most of the existing life extension decision-making models are restricted solely to either "technical" or "economic" feasibility analyses that may lead to inaccurate results or incorrect conclusions.
"You should not assume that all that we could do or have been doing is restricted solely to Benghazi," Mr. Holder said.
Further, presumably payments being outlawed would not be restricted solely to cash; so any two people on a romantic date had better ensure they pay for their own food and drink, to avoid any misunderstandings.
To assess the potential impact of differing diagnostic methods, we re-analysed all cases restricting solely to those positive by DFA.
All the speakers restricted themselves solely to the situation which has developed since the Leipzig incident.
And until the passage of the 1965 Voting Rights Act, African-Americans' right to the franchise was aggressively restricted based solely on race.
Nevertheless, Carle called the espionage charge against Kiriakou "chilling," and noted that it had previously been restricted almost solely for use against spies in the employ of foreign powers.
Physiopathology of CLI is indeed complex and not restricted to solely a lack of tissue perfusion.
