The ‘solvency certificate,’ which is also known as a ‘capability certificate’ is a letter from your banker stating that you are capable of raising funds equivalent to your tuition fees and costs of living in the United States. Most bankers are willing to give these certificates to their regular customers. This certificate is one of the documents that you will need to send along with your application form to the university that you are applying to.
Note that if the university to which you are applying demands a ‘bank certificate’ indicating the actual funds available in your bank account, then a solvency certificate will not be acceptable.