Bom dia,
Experimente dessa forma (SQL Server 2008 ou mais recente):
SELECT cast(DataSolicitacao as date) as DataSolicitacao, count(*) as Total
FROM Solicitacao
GROUP BY cast(DataSolicitacao as date)
ou
SELECT DATEADD(DAY, DATEDIFF(DAY, 0, DataSolicitacao), 0) AS DataSolicitacao, count(*) as Total
FROM Solicitacao
GROUP BY DATEADD(DAY, DATEDIFF(DAY, 0, DataSolicitacao), 0)
Espero que ajude.
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