The Minnesota Department of Commerce recently published a document on "Hiring a Renewable Energy Consultant," which includes contact information for various companies in MN. This document also covers solar electric and solar hot water systems, and is a good "rule of thumb" on what to be aware of when shopping for a consultant. As specified in the document, the list of companies is not an endorsement, but instead a place to begin.
http://www.state.mn.us/mn/externalDocs/Commerce/Hiring_...2010223_How2Hire.pdf
Be choosey and know your options!